How to Setup GPS Rescue in Betaflight (FPV Drone Return to Home)

by Oscar
Flyfishrc M8qmc Gps Size Compare Bn180

Betaflight GPS Rescue mode is similar to “Return to Home” on a DJI drone. This feature is designed to fly your FPV drone back to its launch point and land it automatically in a failsafe or when your video feed gets sketchy. In this tutorial, I’m going to walk you through setting up GPS Rescue Mode, testing it, and I’ll also share some tips on enhancing its performance and troubleshooting common issues.

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Why GPS Rescue is a Game-Changer

Betaflight’s default failsafe action is dropping the quad to the ground. Now, with the latest GPS Rescue Mode, your drone can return close to its launch point and land by itself! This is incredibly useful for long-range flights. Honestly, I’ve lost count of how many times GPS Rescue has saved my drones.

Picking the Right GPS Module

Top Performer – HGLRC M100 Mini

Smallest Worth Having GPS – GOKU GM10 Nano V3

Opting for a smaller GPS module helps save weight, but it does mean you’ll sacrifice a bit of sensitivity that comes with models with a large antenna.

Hglrc M100 Mini Gps Flywoo Goku Gm10 Nano V3 Bn220 $4 Vk2828u7g5lf

I also have good experience with the BN-220 (on average over 20 satellites within a couple of minutes). Yet, it’s equipped with the older M8 chip, meaning it generally takes longer to lock on to satellites compared to the newer M10 chips. If you are struggling to get decent performance with this GPS, you can try optimizing the settings as shown here.

Get the BN-220 here:

If you’re interested in a GPS module with an onboard compass, Flywoo has options, although it’s not necessary for Betaflight’s GPS Rescue mode to work. The modules listed above should suffice for Betaflight users.

Get the BN880 here:

Generation of GPS Chip

Most GPS modules for FPV drones use either an M8 or M10 chip. M10 chips are newer and offer better performance, capable of connecting simultaneously to four Global GNSS systems (GPS, Galileo, Glonass, and Beidou). This results in faster lock-ons and connections to more satellites, especially in areas with interference or limited sky view. Despite their superior performance, M10 units aren’t much more expensive than M8 units, making them a cost-effective upgrade.

Antenna Scratches

Noticed scratches on your GPS antenna’s metallic patch? Don’t worry; this isn’t necessarily a sign of defect or damage. It’s often the result of factory tuning to ensure optimal frequency. These types of antenna have a nominal tuned frequency, but are often impacted by construction, components location and soldering. Placing small nicks in the centre of the long edges, or corners, can fine tune its frequency.

Is a Barometer Needed?

A barometer measures altitude using air pressure, and while many flight controllers come with one built-in, e.g. the BMP280 (such as the Speedybee F405 V4 and RushFPV F722 V2), it’s not a must for GPS Rescue mode. However, having a barometer can improve altitude control. Just remember, if you’re applying conformal coating for water resistance, avoid covering the barometer.

Some GPS modules offer a built-in barometer for an extra cost. If your flight controller doesn’t have one, adding a module with a barometer could be beneficial.

Is a Compass Necessary?

A compass (as known as magnetometer in Betaflight) is for determining directions.

Some GPS modules offer built-in compass, which can be connected to the FC via the i2c port (SCL and SDA). However, Betaflight Rescue Mode doesn’t require a compass to work, it can work out its direction from GPS data.

In fact, an improperly calibrated compass might cause more issues than it solves. In my tests, Rescue mode worked perfectly fine without a compass.

How to tell if a GPS module has built-in compass? If it has 6 wires or solder pads, it means it has a compass – 5V and GND for power,  TX and RX is for the GPS, and SCL and SDA (i2c port) are for the compass. If it doesn’t have a compass, then there should only be 4 wires/pads – 5V, GND, TX and RX.

Connecting GPS to Flight Controller

Wiring a GPS module to the flight controller is quite straightforward. Simply connect it directly to any available UART on the FC, (TX to RX, RX to TX), and power it with 5V.

  • GPS RX – FC TX
  • GPS TX – FC RX
  • GPS 5V – FC 5V
  • GPS GND – FC GND
  • GPS SDA – FC SDA (if GPS has a compass/barometer)
  • GPS SCL – FC SCL (if GPS has a compass/barometer)

Avoid using Softserial for your GPS connection, as it’s limited to a 19200 baud rate. At 9600 baud, GPS reliability for Rescue Mode is compromised. A hardware serial port is your best option for a stable and reliable connection.

Gps Flight Controller Fc Connection Wiring Fpv Drone Betaflight Bn220 Bn180

Some flight controllers, like the Speedybee F405, feature 4V5 pads. These are essentially the same as 5V pads but have the added benefit of drawing power from USB. This is particularly handy for those times when the GPS is taking a while searching for satellites. By using the USB for power, you avoid the risk of your VTX overheating while waiting on the ground with a LiPo battery plugged in. It also helps the GPS lock faster since the VTX isn’t transmitting and causing interference. Note that some FCs might offer 5V pads powered by USB but under different labels; check with a multimeter if unsure.

How to Setup GPS in Betaflight

GPS Rescue mode in Betaflight is continuously evolving, so it’s crucial to use the latest firmware version for new features and bug fixes. I recommend upgrading to Betaflight v4.5 for this process: https://oscarliang.com/betaflight-4-5/

First, in the Configuration tab of the Betaflight Configurator, activate GPS for navigation and telemetry under the Other Features section. If GPS always deactivates after a reboot, it might be due to not selecting GPS in the Cloud Build options during firmware flashing.

Betaflight 4.5 Gps Rescue Setup Enable Feature Configuration

Next, in the Ports tab, assign GPS to the appropriate UART under “Sensor Input.” Betaflight supports various baud rates: 9600, 19200, 38400, 57600, 115200. If you are unsure what baudrate your GPS module supports, selecting AUTO usually works. If not, 57600 or 115200 are common rates in GPS modules.

Gps Setup Betaflight Ports Uart Auto Baud

In the GPS tab, do the following:

  • Select UBLOX as the Protocol, which is the standard for most GPS.
  • Enable Auto Config.
  • Enable Use Galileo – it improves positioning accuracy.
  • Enable Set Home Point Once to prevent resetting the home location with each arm/disarm cycle until you unplug the battery.
  • Choose Auto-detect for Ground Assistance Type to enhance positioning accuracy.
  • Save and Reboot.

Betaflight 4.5 Gps Rescue Setup Configuration Settings

After setting up, the GPS indicator at the top of the configurator should light up, indicating communication with the FC. A red icon means GPS is talking to the FC but without a lock, and a yellow icon indicates a successful GPS lock.

If the GPS indicator remains off, check for

  1. GPS is not powered? Try plugging in battery?
  2. Incorrect parameters, for instance, wrong baud rate or protocol.
  3. Incorrect wiring, try swapping TX and RX.

Betaflight 4.5 Gps Rescue Setup Top Icon Red Yellow

How to check if GPS is working?

Wondering if your GPS module is talking to the flight controller? The ‘gpspassthrough’ command in the CLI can reveal any ongoing data exchange. Seeing a stream of binary data means communication is happening.

Run the ‘gpspassthrough‘ command in the CLI can reveal any ongoing data exchange between the FC and GPS.

Seeing a stream of hieroglyphic binary data characters means communication is happening. If you see nothing, there may be an issue with power, UART connection, or your setup.

Gps U Center Betaflight Cli Serial Passthrough

Waiting for GPS Lock

Getting a GPS lock, or “3D fix,” requires locking onto at least four satellites and can take a few minutes.

When you power up the GPS module for the first time in a new location, it always takes longer to search for satellites, known as a “cold start”. Subsequent starts tend to be quicker as the module remembers satellite positions (for example when you change battery).

It’s harder to get a lock indoor. If you have to test this inside the house, try to get close to the windows with the antenna pointing to the sky.

You will see GPS related information under the GPS tab, where it shows the status of your lock, your GPS coordinates and location on a map, verifying the accuracy of your GPS lock.

Betaflight 4.5 Gps Rescue Setup Map Current Location

LED Indicators

On most GPS such as the BN220, BN180 and BN880, there are two LED indicators, labelled “TX” (usually blue) and “PPS” (usually red).

Flashing blue (TX) indicates UART connection. If it is off, then the GPS is not sending data out. This is also an indicator of the refresh rate, in 1Hz it should flash once per second, while in 5Hz it will flash 5 times a second.

Flashing red (PPS) indicates the 2D/3D fix status of the GPS. If “PPS” is off then you don’t have a fix yet.

When it gets a 3D fix, the red LED on the BN-220 module should blink (together with the blue LED).

OSD

You can display GPS info in the OSD. Check out this tutorial about Betaflight OSD if you are not familiar with it. You can display GPS coordinates, distance and direction to home and more.

Gps Osd Elements Betaflight Home Arror Direction Distance Speed Coordinates

To know how many satellite have been acquired, place the gps sats element in your OSD. 6-8 is the minimum for rescue mode to work, the more the better. Your GPS coordinates will also get more accurate when you acquire more satellites.

Gps Sats Satellites Lock Osd Element Betaflight

You can also display HDOP next to the number of satellites. HDOP is a measurement of the health of the GPS locks. A HDOP value of 1 or below is ideal, which would give you an accuracy of about 2.5 meters or less. It might be oversimplying, but just think of it as how much the drone would be drifting horizontally in meters.

To do this, go to the CLI, and enter:

set osd_gps_sats_show_hdop = on

save

Radio Telemetry

Once you have GPS setup and got a lock, go to the radio’s telemetry page, select “Discover new sensors”. Some GPS related new sensors should appear including GPS coordinates. This only works if your radio system supports Telemetry – such as ExpressLRS and Crossfire.

This allows you to log GPS coordinates in your radio, it allows you to keep track of the last known position of your aircraft. This can be helpful for searching for the lost quadcopter if you can’t see the coordinates in your DVR.

Testing Angle Mode

Betaflight’s GPS Rescue mode relies on Angle mode — a self-leveling flight mode — to stabilize the drone. Therefore, it’s essential to ensure Angle mode is functioning correctly.

First, verify that the Accelerometer is enabled in the Configuration tab.

Betaflight Configurator 10.9.0 Configuration Accelerometer Enable

Next, proceed to the Setup tab and calibrate the Accelerometer on a level surface. Failure to do so might result in the drone drifting while in Angle mode.

Betaflight Configurator Setup 10.8

To test Angle mode, try hovering the drone to see if it’s self-levelling as expected. Remember, Angle mode uses only the Accelerometer and Gyro, so it won’t keep the drone perfectly stationary like a DJI drone would. A slight drift due to weight distribution and wind is normal, as long as the drone remains stable. If drifting is noticeable, you can trim the accelerometer in the Configuration tab to minimize it (but unlikely to completely eliminate it so don’t worry).

Also, take note of the throttle position during hover. This value will be useful when setting up Rescue mode later.

Enabling GPS Rescue Mode in Failsafe

Navigate to the Failsafe tab in the Betaflight Configurator. If you can’t find this tab, make sure you’ve enabled the “Expert Mode” option at the top of the screen (next to the Update Firmware button).

Betaflight 4.3 Configurator 10.8 Expert Mode Enabled Pid Tuning

Under Stage 2, select GPS Rescue. Now, if your drone enters failsafe, it will trigger GPS Rescue Mode.

betaflight gps rescue mode failsafe

So, what exactly is failsafe, and what are stage 1 and stage 2? Here’s a quick rundown: Your drone enters failsafe upon losing radio signal. By default, it would just drop to the ground, but with Rescue Mode, it will attempt to return home.

During a failsafe, your drone will first enter Stage 1, pausing briefly (guard time) to see if the signal returns. If not, it progresses to Stage 2, activating Rescue mode to bring the quad back.

While setting GPS Rescue as your failsafe method is beneficial, it’s not suited for all environments. For instance, it’s not advisable in bando, forests, stadiums, or indoors. Losing control under a tree or inside a building could result in the drone crashing into obstacles when Rescue mode engages.

If you have no GPS lock when it failsafes, the quad will (should) just drop to the ground.

What Happens after Rescue Mode is Activated?

Watch GPS Rescue Mode in action here:

Rescue mode involves 5 phases:

  1. Ascend: The drone climbs to a predetermined altitude or the maximum altitude reached during that flight.
  2. Rotate: It turns towards the home direction.
  3. Fly Home: The drone begins its journey back to the launch point. The flight might not be a smooth cruise, exhibiting some lateral movements as it navigates home, but it will eventually arrive.
  4. Descend: Once near the launch point, within a 5x5m area, it starts descending slowly. The descent might be uneven, with the motors making pulsating sounds as the drone tries to slow down.
  5. Land: Upon touching the ground, the drone automatically disarms, with motors terminating based on impact, not based on altitude.

How to Stop Rescue Mode

If Rescue mode was activated via a switch, regaining full control is as simple as disengaging that switch.

If activated by failsafe:

  • If it’s a real failsafe triggered by a loss radio link, the pilot must move the sticks more than 30% to regain control after radio link comes back.
  • If the failsafe was triggered manually via a switch, simply disengage the failsafe switch — no need to wiggle the sticks.

GPS Rescue Settings Explained

Settings for GPS Rescue mode are available in the Failsafe tab.

Betaflight 4.5 Gps Rescue Setup Failsafe Settings

You have to tweak the GPS Rescue settings in Betaflight to your specific setup and environment. I highly recommend visiting the Betaflight wiki to grasp a full understanding of what each parameter entails: https://github.com/betaflight/betaflight/pull/11579. The default settings offer a solid starting point, especially for 5″ freestyle drones.

Here, I’ll walk you through the settings, sharing the values I use on my 5″ freestyle drone and the reasoning behind each choice.

Accessing all settings is straightforward via CLI—just enter get gps_rescue for a comprehensive list of GPS-related parameters. However, adjusting them in the GUI (Failsafe tab) tends to be more user-friendly.


Altitude Mode: It determines the altitude at which the quad returns home.

  • Maximum altitude is the highest altitude your quad is flown during that flight
  • Fixed altitude is just a predefined value
  • Current altitude is whatever height that the quad is at when GPS rescue mode is activated

The best choice varies with each flight’s context and environment. Maximum altitude can be a safe option, but it’s not always the right option. For instance, if you was diving a mountain in that flight, you could be wasting energy climbing back to the max altitude when Rescue mode is activated. Be adaptive to the different environment and missions.


Initial Climb (meters): The distance the quad will climb, above the current altitude, when a rescue is initiated and the altitude mode is set to Current Altitude. Also added when in Max Altitude Mode.


Return Altitude (meters): Only applies in Fixed Altitude mode. This determines the drone’s return altitude relative to its takeoff point. It should be high enough to clear any obstacles like trees and buildings but not so high that it excessively consumes battery during ascent. For my flying spots, which features tall trees and hills, I’ve bumped this up to 50 meters.


Ascend/Descend Rate (meters/second): These rates depend on your environment, weather, and quad’s power. For my 5″ setup, the defaults should work well. If using Li-ion packs or low C-rating LiPo, consider a lower ascend rate.


Return ground speed (meters/second): This is the speed at which the quad travels during Rescue. The default 5m/s is 18km/h which I find too slow, I doubled that to 10m/s which is 36km/h. The quad’s travel direction would be more accurate and update faster in higher speed (in the absence of a compass). Do not set it to lower than 2m/s or orientation won’t work. Note when entering this value in GUI, the unit is different than CLI (which is cm/s).


Maximum Pitch Angle: This setting caps the drone’s tilt angle. A higher angle leads to more aggressive returns and higher speed. Maybe useful for heavier, high drag and low authority drones. In windy conditions, a higher angle might be necessary for maintaining speed, especially for smaller quads. However, with an excessively steep angle the drone could lose altitude and crash. Unsure of what to set? Starting with the default value of 40 degrees is a safe bet—it’s worked well for my setup.


Descend Distance (meters): This is the distance from home our drone starts to descend. I stick with the default here.


Throttle minimum, Throttle maximum, Throttle hover –  these are the min, max and hover throttle values you want to use during Rescue mode. Set maximum so the quad isn’t too fast/jerky (it should be above your hover point), set min to keep the props spinning at a reasonable rate (it should be lower than your hover point). I left Throttle Min/Max at default.

To set Throttle Hover, you need to determine an accurate value. Test fly your quad and see at exactly what throttle it hovers (just enough throttle to keep the quad afloat), literally every quad is different. Use the “Throttle %” OSD element to get the exact value instead of just guessing. According to info in the pull request, “the correct value should cause the quad to climb a bit while in level mode… If these values are set too low, the quad will drop early in the rescue – possibly into the water!”.


Minimum Distance to Home (meters): If Rescue starts too close to home (within this minimum distance), the drone will fly away on its current heading until this distance from home, and start the normal Rescue behaviour. I leave this at the default 15 meters.


Minimum Satellites: A minimum of 8 satellites ensures reliable Rescue mode operation. If you take off before the GPS reach the minimum amount of satellites, it won’t know the exact home location. More satellites mean better accuracy. I leave this at the default, 8.


Allow Arming Without Fix: This option provides flexibility by allowing arming without a GPS lock. I enable this for the convenience of test flights, but ensure you get a GPS lock for when you intend to use GPS Rescue Mode.

Beware that GPS Rescue WILL NOT work for that flight if you arm before getting a satellite lock (because it doesn’t know the home position).

If you have trouble getting these many sats (or it takes a long time), check out my tutorial on how to boost your GPS receiver performance. Get a new GPS if you must, they only cost $15, a great investment for protecting your $300 quad!


Sanity Checks: When set to “ON”, it monitors GPS Rescue mode conditions, for example:

  • Is the GPS still connected to the FC?
  • Are we getting a good number of satellite locks?
  • Are we at least 20 meters away from home?
  • Are we getting closer to the home, and we didn’t hit an obstacle?

If any of these conditions are not met, it will abort rescue mode and your quad will just disarm and drop to the ground. So yea, it’s not ideal if you are flying over unrecoverable places like ocean or mountains, but generally, it should be on for safety reasons.

The Betaflight wiki also recommends setting Sanity Checks to “Failsafe Only” if you are having trouble with the option “On” during testing. It turns Sanity Checks off when Rescue mode is activated by a switch but only turns it on when it’s in failsafe. This is also my preferred option.

It’s risky to turn off Sanity Check entirely, you might get an indefinite flyaway. In Betaflight 4.4, there is now a limit of 20s of sanity failure even if all sanity checks are off. It is a safety thing. Never fly with all sanity checks off.

How to Manually Activate GPS Rescue?

Besides failsafe, you have the option to manually trigger GPS Rescue by flipping a switch on your radio transmitter. This feature comes in handy during emergencies, such as losing your way or encountering issues with your FPV system, allowing your drone to autonomously return home.

Go to the Modes tab in Betaflight Configurator and assign an AUX channel specifically for GPS Rescue Mode. If you’re new to configuring modes, check out my tutorial here: https://oscarliang.com/betaflight-modes/

betaflight gps rescue mode switch activate

Throttle Channel Fallback

During Stage 1 of a failsafe, your drone goes into channel fallback, meaning each radio channel is set to predefined values. It’s wise to review these values to ensure safety.

By default, the Channel Fallback for Throttle is set to “Auto,” which reduces the throttle to zero, results in the motors stopping momentarily during the guard time. This interruption could destabilize the drone before GPS Rescue kicks in, potentially failing a sanity check and causing the drone to drop to the ground.

One solution is to adjust the Throttle Channel Fallback from “Auto” to “Hold,” maintaining the last throttle value throughout the guard time, preventing motor stalling.

However, I personally prefer setting the throttle to the hover value, as well as centering all roll/pitch/yaw channels, and engaging Angle mode. This way, the quad levels itself and doesn’t ascend or descend when failsafe happens, before GPS Rescue engages.

Remember, never set throttle to zero during Stage 1 of failsafe!

Betaflight Configurator Failsafe Gps Resuce Settings Bf 4.4

How to Test GPS Rescue

Testing GPS Rescue is a crucial step before relying on it in real-world scenarios. Here’s my approach to ensuring it works as expected.

The Setup

First, assign a switch on your radio to GPS Rescue to confirm it can indeed bring your drone home. Should anything not go according to plan, flicking the switch off should immediately return control to you.

Next, allocate another switch to Failsafe in the Modes tab. This simulates a full failsafe event, just like losing RC signal, but in a much safer manner since you can exit the mode whenever necessary using the switch. It’s important to note that this setup is strictly for testing purposes. Once you’re finished, remember to remove Failsafe in the Modes tab.

Betaflight Configurator Modes Failsafe

With the propellers removed, head to the Modes tab and ensure that activating the Failsafe switch indeed triggers Rescue mode, during which your radio sticks will be momentarily locked out. Verify if you can exit failsafe mode and regain control smoothly.

While bench testing with a USB connection, the Rescue mode indicator might not illuminate as other flight modes do. However, as long as the small yellow bar bar moves into the activation zone, it’s working correctly.

Incorporating GPS-related information into your OSD is beneficial, providing insights into the drone’s status. The Flight Mode indicator is particularly helpful, displaying “RESC” when in Rescue mode, “Air” in rate mode, and “Angle” in angle mode.

Field Testing

For an actual test, choose an open area free from obstacles and people. Ensure the OSD shows a sufficient number of locked satellites before arming.

Take off and fly in a straight line for 100-200 meters, then trigger Failsafe mode using the switch. The quad should promptly switch to GPS Rescue mode—observe this transition in the OSD’s flight mode display.

Pay attention to the home arrow in the OSD; when it’s pointing up, means you’re heading home, when pointing down means you’re flying away. Initially, the arrow might point in the wrong direction, which is normal as it takes a few seconds for Betaflight to work out which direction it’s heading—just ensure the drone isn’t flying the complete opposite direction.

You can quit failsafe mode at any time by flipping the switch, regaining full control immediately.

If you choose not to disengage, the drone will continue flying back to the launch point. Upon arrival, it will hover briefly before starting a slow descent, during which the motors may pulsate, until it safely lands and disarms automatically.

Repeat this process a few times, until you’re confident in the system’s reliability. After thorough testing, don’t forget to remove Failsafe from the Modes tab.

Tips and Troubleshooting

Best Places to Mount GPS Module

Making sure your GPS module’s ceramic patch antenna has an unobstructed view of the sky is crucial for quick and reliable satellite lock-on. Anything covering it, particularly conductive materials like carbon fiber, electrical wires, or metal, can significantly weaken the GPS signal.

Avoiding EMI

Electromagnetic interference (EMI) from other electrical components on your quad can also affect GPS performance. Notable sources of RF interference include HD cameras and video transmitters. To mitigate this, mount your GPS as far away from these devices as possible.

Proper Mounting Orientation

A common error is mounting the GPS upside down. The receiver antenna, identifiable by its flat square shape with a small metal circular part in the center, should always face upwards. Ensure no components obstruct this side. In the following image for example, the ceramic antenna is facing up.

Holybro Nano Ublox M8 5883 Gps Module

Placement Strategies

Make sure there’s nothing blocking the GPS unit at all times. Ideal mounting spots include the top of your quad, far away from VTX and RX antennas, and away from potential radiation sources like HD cameras lacking proper shielding. Here are a few mounting ideas:

Hglrc Sector X5 Bnf Fpv Drone Rx Vtx Antenna Gps 3d Print

Stp Hobby Armor 5 Fpv Drone Rushfpv Rx Vtx Antenna Gps Mount

On top of your GoPro/HD camera.

On top of the frame if using an under-slung battery setup.

On a mast to elevate the GPS away from the quad. However, be cautious of proximity to VTX antennas.

Getting a GPS Lock Faster

Most GPS modules feature a small battery to store satellite data and time, aiding faster lock-on. Once the GPS has locked onto satellites, it retains their positions for quick reconnection after battery changes. If your GPS consistently takes long to lock, check if its battery is depleted using a multimeter. Minimize interference as much as possible—for instance, by relocating a powerful VTX, especially if you’re on a 1.3GHz FPV setup. Weather conditions like cloudy days can also impact GPS signal quality.

For more tips on optimizing BN220 for increased satellite locks, check out my dedicated tutorial: https://oscarliang.com/gps-settings-u-center/

Suggestions directly from Betaflight Developers

I recommend 10 satellites. [And] Wait for 30s after [you have] 10 satellites for altitude to stabilise [before taking off].

Always confirm normal GPS Rescue behaviour at the start of a critical flight by testing with the failsafe switch. Set the switch to immediately enter Stage 2. You can enter and leave GPS Rescue via the switch with immediate on and off effect. Check that the quad rotates and flies towards home and does the right things before you are so far away that a true failsafe may occur.

ALWAYS CHECK that the Home Arrow points directly back towards home after takeoff! Sometimes, if you take off and spin around during arming or immediately on takeoff, the quad’s attitude information can become corrupted, and the Home Arrow can point the wrong way. It’s best to arm cleanly and fly away from Home in a straight line at a reasonable speed immediately after takeoff. Watch the Home Arrow carefully to ensure it quickly points back to Home. If the Home Arrow points the wrong way when a failsafe occurs, the GPS Rescue will initially fly off in the wrong direction, and in some cases, you may lose the quad.

Wrong Direction in Rescue Mode?

Without a compass, rescue mode should still work as the quads calculate direction through GPS data comparison.

At the beginning, your quad might be wandering around or even flying towards the wrong direction but eventually it should self-correct. With weak GPS connection, it can take longer to correct.

If you are using a compass and it’s flying the wrong direction, then maybe there’s something wrong with the compass, or maybe it’s not calibrated properly. In this case try turning off magnetometer in Betaflight and try again. If it works now, it proves your compass is the source of the problem.

If your yaw is jerky during Rescue mode, your GPS might be updating too slowly (e.g. 1Hz), try to increase it to 5Hz or even 10Hz following this guide (only works on certain GPS modules).

Avoid Softserial

Avoid using Softserial for GPS, as it only supports up to 19200 baud rate, and with 9600 baudrate the GPS is simply not reliable enough for GPS features. It’s best to use a hardware serial port (any TX and RX pins on the FC), and set baudrate to at least 57600.

Not Getting GPS Lock

Interference from your quad’s electronics, such as the VTX, telemetry-equipped radio receivers, or even wires carrying significant current, can hinder your GPS’s ability to lock onto satellites. If you’re facing difficulties achieving a GPS lock, consider the following steps:

  • Power the Flight Controller (FC) via USB to check if it powers the GPS module. If not, move the GPS module’s power connection to a different pad on the FC that gets power from the USB port.
  • Isolate the FC’s Power Supply: Powering only the FC without the VTX can help you get a quicker GPS lock. Nevertheless, it’s advisable to mount your GPS as far as possible from both the VTX and RX antennas to minimize potential interference.
  • Shielding Electrical Wires: shielding wires that conduct significant current can mitigate interference. These wires can act like antennas, potentially disrupting GPS signals.

GPS satellites operate on two frequencies, L1 1575.42MHz and L2 1227.60MHz. Consequently, a 1.3GHz FPV setup might interfere with your GPS. The majority of pilots use 5.8GHz, which generally avoids this problem. However, given the weak GPS signal—originating from satellites in space—even strong nearby signals can cause interference. Thus, positioning the GPS module away from any transmission sources is crucial.

Running GPS wires under the VTX can cause issues, particularly if the VTX lacks adequate RF shielding. This RF noise can compromise GPS functionality. For example, the Avatar VTX V1 was known to cause GPS problems when wires are routed underneath it. A potential fix involves grounding the VTX’s shielding. Alternatively, shielding the wires between the GPS and FC—and ensuring they’re grounded—might offer a solution.

Gps Wire Cable Ground Shielding Foil Betaflight Fc

I tried to shield wires with foil in one of my builds, then connected the foil to a ground pad on the FC. After wrapping it with cloth tape to prevent short-circuiting the frame, I noticed minimal improvement. While some have reported positive outcomes with this modification, it’s worth exploring if other straightforward solutions are unavailable.

Failed to Activate GPS After Updating Betaflight

If you’re unable to enable GPS after flashing the latest Betaflight version, it’s possible that some features including GPS were excluded from the compiled firmware – a new feature called Cloud Build System.

To verify if this is the problem, enter the following command in the CLI:

feature gps

Should the CLI respond with “gps not available,” it indicates that the GPS functionality was not included in your FC’s Betaflight firmware. To resolve this, you’ll need to reflash your FC. This time, ensure that the GPS option is selected in the Cloud Build system during compilation: https://oscarliang.com/flash-update-betaflight/#Cloud-Build-System

Understanding GPS Coordinates Precision

When displaying GPS coordinates in the OSD, you’re provided with options to choose the number of decimal places shown—currently, only 4 and 7 decimal options are available. This selection directly influences how accurately you can pinpoint a location on a map based on the GPS data.

The “Decimal Degrees” Wikipedia page provides a detailed table comparing degree precision to physical distance:

decimal
places   degrees          distance
-------  -------          --------
0        1                111  km
1        0.1              11.1 km
2        0.01             1.11 km
3        0.001            111  m
4        0.0001           11.1 m
5        0.00001          1.11 m
6        0.000001         11.1 cm
7        0.0000001        1.11 cm
8        0.00000001       1.11 mm

It’s crucial to differentiate between accuracy and precision in this context. The GPS may display a high degree of precision (number of digits), but not all decimal places may reflect true accuracy. This means that while your GPS can report coordinates to a very fine resolution, the actual accuracy—how close those coordinates are to the real location—may vary.

Edit History

  • Oct 2018: Tutorial creation.
  • Aug 2020: Updates for GUI and CLI parameter changes, addition of throttle settings.
  • Feb 2023: BF4.4 update with auto-landing feature.
  • Mar 2024: BF4.5 update.

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109 comments

Greg 29th April 2024 - 3:34 pm

This needs to be updated because HDop is now PDop in BF4.5 full release. Exact same CLI entry just change to PDop.

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Tomcat2 27th March 2024 - 1:04 am

I’m curious how you determine the Throttle hower value? It differs when the battery is fully charged and when it is almost empty. So, if the value is determined in fully charged state, the drone will fall to the ground when the Rescue mode triggers and the battery is low. Also the opposite, when the hover throttle value is determined in the low battery state, the drone will shoot to the sky when the Rescue mode trigers with fully charged battery. For my quad even a small nuance in the throttle makes a big difference if it hovers, descends or ascends and the hover value moves up, when the battery is low…anyone thought about that?

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Jorge Vidal 17th March 2024 - 8:39 pm

Excelente!!! Maestro!! Muchas gracias.

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calmar von Flims 9th May 2023 - 11:58 pm

Great job – especially also ‘the details’. thx.
Even so: when in rescue-mode, you can also use the throttle? I guess not, right?

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Oscar 10th May 2023 - 10:45 am

No, you have no control on throttle as it’s managed by the Initial Altitude value.

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Capone 11th March 2024 - 9:31 pm

Hello: avaible for immersionrc vortex 250 / 230 mojo ?? Thanks

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George 22nd April 2023 - 4:44 pm

when the nano rx tbs failsafe is cut??the failsafe is working?

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Francisco SotoMeior 24th April 2023 - 3:07 pm

Correct!

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Joshua 13th April 2023 - 3:27 pm

Hey Oscar,

As of April 2023, what GPS is the best right now for 5inch and whoops? Will be used with BF4.4 return to home

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Oscar 13th April 2023 - 4:05 pm

I shall update the list of GPS here soon, but for now please refer to the latest GPS that i recommend: https://oscarliang.com/best-5-inch-fpv-drone-parts/#Accessories

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Sean 6th March 2023 - 12:35 am

Is failsafe in Betaflight activated on Vtx loss, as well? Or just radio link loss? It’s not clear to me what happens if there is video loss. I’m assuming the failsafe is not activated, and that’s why we should keep GPS rescue on a switch. I just want to be 100% sure!

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Oscar 6th March 2023 - 2:02 am

No. However you can manually activate Rescue mode in the event of a video loss. You can assign GPS Rescue mode to a switch on your radio. Failsafe mode is only for testing, you should remove it as soon as you are done with testing.

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Carlos 3rd March 2023 - 10:20 am

Hi Oscar, very nice post

I have tried to activate rescue mode (switch) at low altitude (4-5m) and it drops to the ground. Could be related with the initial altitude parameter? Is it necesary to activate rescue highier than this parameter?

Thanks

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Oscar 3rd March 2023 - 11:10 am

It should still work at this height. Were you outside of the minimum distance to home? And did you have enough satellites? If it just drops to the ground, sanity check is probably didn’t go through because something was wrong.

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calmar 10th May 2023 - 12:01 am

May also test it .. when it’s actually on the ground. Initially. (ps: maybe your hoover-number is wrong?). I used the black-box to figure out that hoover-value.

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Austin 20th October 2023 - 11:48 pm

I had this same issue and it was because I had left Throttle fallback to AUTO. The problem went away when I set that fallback to “SET” and the correct hover value.

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Bob 6th February 2023 - 10:18 pm

Very coo! What happens if you have no satellites and the quad goes into failsafe?

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Oscar 7th February 2023 - 12:31 am

it should just drop to the ground.

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Bertin 2nd February 2023 - 2:58 pm

Merci beaucoup pour cette belle explication 👏👏👏

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Szorfos 4th July 2022 - 8:34 pm

Hello Oscar!
Thank you for your post, it helped me a lot! I could set up the GPS properly, but after I updated the firmware for the Betaflight 4.3, the GPS is not working anymore. No gps sign, nor any gps data on the gps tab. Do you know any solutions? I used the same settings as before. (HGLRC M80pro with a geprc cinelog 35 flight controller and caddx vista.)
Thank you for your help!

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stefan aka snakeye fpv 16th June 2022 - 4:10 pm

it’s really great that you take the trouble to write all this information together instead of putting it all in one youtube video. thank you very much for the hard work. please go on!

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Austin 20th October 2023 - 11:51 pm

Amen to a searchable written document instead of a youtube video!

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Brian 20th April 2022 - 11:10 am

hej i have the tyro 119 with the accst taranis x9d
build it all and it all works
if i install all the modes on bf it works until i come to gps rescue or failsafe
then nothing on the quad will work even if i put all the modes back
need to restart the quad and the taranis and start all over again.

then if i do all the basic stuff the quad and taranis work and i can fly but nog with gps if i put it on it is okay but when i want to set the failsafe or gps rescue it is again blocked up and need to restart

WHO CAN HELP!!!

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Patrick 22nd December 2022 - 1:09 am

I have the same exact problem, it will get stuck in rescue / fail-safe mode and wont come out when you flip the switch or turn on the radio and all controls are locked out until FC is rebooted

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JTHFPV 21st February 2022 - 6:32 pm

Hi Oscar, I saw a reviewer saying that GPS rescue triggers on critical low battery? Is this true?

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David yousefi 2nd January 2022 - 10:33 pm

Hi Oscar, some say put throttle in hold some say leave it in auto, I trust you so you tell us please

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Eri Rubin 30th October 2021 - 10:04 am

Hi, is there a way to warm start the gps position ? i.e. connect the drone to a mobile phone, and send it the current position ?

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Anyelo 17th November 2021 - 8:16 pm

TBS CROSSFIRE/ TRACER – MAVLink by WiFi

Ground control software like Mission Planner or APP QGroundControl

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Curtis Cooper 21st July 2021 - 6:53 am

How it going Oscar I have a novice 4 that I enabled gps rescue to an aux switch now I can’t arm it in drop or land mode in the osd anymore? Before I assigned the switch I could arm in drop or land but couldn’t in gps ” I know because I didn’t have the required 6 sats” also the arm without fix was disabled from the factory all I wanted was gps rescue on an aux switch now I have lost the ability to arm in drop or land and even gps unless I get the minimum sats why is this happening? Also my 3d fix says false but
with this model all I was so supposed to be able to do was enable gps rescue which was done factory already and just assign my aux switch and that’s it but now I’m having these issues unless I turn off take off without a fix Thanks man I would love to hear back for this issue

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Oscar 21st July 2021 - 5:59 pm

If you enable “warning” in OSD element, that should tell you why it’s not arming on the screen?
If that doesn’t say it, you can follow my troubleshooting guide to find out why it’s not arming.

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Adrian 14th July 2021 - 10:33 pm

What is low throttle delay

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Matthew 6th July 2021 - 9:01 am

Hi Oscar, Ive set up GPS rescue on my Iflight XL5 Quad HD. Im having issues my GPS Rescue. When I activate via an Aux switch to test it, the quad does not fly towards where it took off from. For what ever reason it always seems to fly off in the same direction no matter how many sats I have. In BF I have it set to a Minimum of 8 sats. The GPS unit has a compass and I have that connected, activated and calibrated. It seems that home point is never correctly set when I take off… Im at a loss as to what could be the issue. The GPS unit sits off the back of the quad underneath the DJI antennas. I’m running crossfire and that antenna is below and behind GPS unit. Do you think these could be causing some sort of issue?? Appreciate your thoughts. Cheers Matt

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Oscar 6th July 2021 - 8:49 pm

Have you tried disconnecting the compass in Betaflight (and the wires)? It should work without compass.
Also get the GPS co-ordinate of your home position from the OSD, and check it in google map see if the location is correct?

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Steve 3rd July 2021 - 2:45 pm

Hi Oscar. I tested failsafe by switching off my radio while the copter was about 5 meters in the air. I noticed that there was about a 1 second pause between when the motors stopped spinning and the GPS rescue kicked in, causing the copter to fall a few meters towards the ground before rising up again. How can I set it up so that the instant the signal is lost the GPS rescue will activate before the motors stop spinning?
My stage 2 guard time was set to 0.4 seconds by default, and throttle fallback was set to Auto.
Would setting the stage 2 guard time to 1 second, or setting throttle fallback to set = 1500 prevent this motor pause at signal loss?
Thanks
Steve

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Oscar 3rd July 2021 - 3:34 pm

Can you try the following:
assign a Aux channel to rescue mode.
in Failsafe tab, Channel fallback settings, set that channel value to activate Rescue mode.
When Failsafe kicks in, Rescue mode should be activated immediately.

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Ollie 12th May 2021 - 9:06 pm

This is really useful. I tested my set up today, on a switch, and everything worked except regaining control.

It came back to me then hovered up and down in front of me. I could not regain control at all.

Reading more into it, I think it may be down to stick deflection. The default is set to 30% which means you need to move a stick more than 30% to regain control.

But flicking the switch out of rescue mode did nothing… would that be the same reason? Because in essence it’s locked in rescue mode until I move a stick more than 30%?

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Ferdinand Wolf 18th November 2021 - 11:29 am

Same for me. You have to move the stick to regain control. I don’t understand, why this is not mentioned at all in Oscars article above!? Can you please comment @Oscar

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Beau 27th April 2022 - 8:12 am

This feature was introduced in Betalight 4.2 whereas I think this article and wiki it was based off at the time were referencing 4.1 where it was not a feature and it was instead recommended to manually switch GPS rescue mode via switch following failsafe. This is no longer required in 4.2 onwards with this new feature (called failsafe_stick_deflection in cli).

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Derron Tume 20th March 2021 - 6:11 pm

Hi Oscar, thanks for the helpful guides, I conformal coated my kakute f7 forgetting about the barometer, my altimeter now gives weird readings, if I setup gps rescue and the board will it have an effect?

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Oscar 20th March 2021 - 7:13 pm

You can disable Barometer in the “Configuration” tab, then altitude will be calculated from GPS data instead.

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박성진 7th December 2020 - 6:59 am

The blue light on the gps flashes, but the gps isn’t activated on the beta light, do you know why?

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Allan 1st October 2020 - 9:08 am

Hey oscar! Thanks for the step by step instructions. My drone’s gps rescue mode works perfectly but now i don’t know what happened. When i activate the gps rescue through a switch, the drone stumbles/stalls while turning. I did another test but this time the drone was already facing the home direction and when gps rescue activated, the drone Ascended and flew back home perfectly. May i know what causes the stall during yaw/turning?

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Oscar 8th January 2021 - 4:22 pm

Just the way it is right now, it has no way of knowing which direction it’s facing as it’s not using a compass, it can only work it out by flying forward and work it out that way that’s why it’s constantly adjusting its course.

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Guy 24th April 2023 - 5:56 pm

Hi Oscar,

Can I have GPS rescue activate only on a switch? I want to leave my Failsafe set to Drop, but have the option to trigger GPS rescue manually. Do I have to set my Failsafe to GPS Rescue for it to work with the switch?

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Tony 18th September 2020 - 11:51 pm

Hey Oscar, I just wanted to say thankyou for all your different how to pages ,, I dont know anyone else who flys ,, your pages helped me with alot of different issues

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Glen Beech 26th August 2020 - 4:31 am

Hello,
I believe I have my Gps rescue set up, it locks on to the satellite’s, but in BF the modes page….I don’t get the gps rescue tab turning yellow when I activate the switch, the marker goes into the yellow range on the slider but the GPS Rescue tab on the left does not turn yellow.I did test the switch in the air 150 meters away, and the quad tumbled from the sky and I lost video as soon as switch flipped? Thanks@

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Oscar 4th September 2020 - 3:57 pm

Put “Flight Mode” in your OSD, in Rescue mode it should change from “Acro” to “Resc”.

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Jon 17th August 2020 - 10:29 pm

Something else I found with beta flight. So instead on the Failsafe tab you can set the value of a switch so that it’s in the active mode. So setting RTH switch to 1800 will have it activate that if it comes within range but forgot to turn on the switch

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Rob Bannister 6th August 2020 - 1:22 am

I tried setting set gps_rescue_min_sats = 0 in betaflight 4.2 and the entry is invalid. The lowest you can put seems to be 5

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Oscar 17th August 2020 - 6:08 pm

if you want to take off without GPS fix, just do this in CLI:
set gps_rescue_allow_arming_without_fix = ON

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Franky 4th July 2020 - 7:21 pm

Great information Oscar,
I already set up rescue mode in betaflight and assign 1 switch on my TX for rescue mode,
Should I set in failsafe in my transmitter as well?
in my TX there is Failsafe mode = not set / hold / custom / no pulses, last time I use custom set (position to arm, level, rescue mode) but it disarm after failsafe 2 seconds, should I just set it to NO PULSE?

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Oscar 8th July 2020 - 11:01 pm

Yes, although failsafe always gets triggered first in Betaflight and that’s all you need, just set it to No Pulse in your radio anyway.

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Ed 4th May 2020 - 8:28 am

Hi Oscar,
So I lost video, hit the switch for Rescue but wasn’t sure so hit throttle anyway, I fly in Acro always, and I did manage to get the quad back but noticed on the HD footage it was fighting my throttle inputs and possibly stick bumps. Curious if that somehow ruins the FC or it just keeps fighting my stick inputs and prolongs my return?

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JEREMY HOLT 9th April 2020 - 11:53 pm

Hey Oscar I installed RDQ mini 8 gps on kakute f7 and when I set a switch and checked in modes tab gps rescue doesnt highlight when switched on. I know in flight it has to be 100 meters away but when testing on the bench I think the mode should highlight like all other switched modes. Any idea what’s going on?

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Ian morris 29th February 2020 - 11:27 am

Hi Oscar. I have set up gps rescue on my quad with the matek 405 std flight controller and all seems to be working well thanks to your great instructions. My only concern is, and bear in mind I have only tested this with the props off on a bench, I have assigned rescue mode to a spare switch on the radio, and when I flick it, sure enough, rescue shows on the goggles screen, my worry is that when I arm the quad on the bench near the window, if I then press the rescue mode switch, it cuts the quads motors, is this just because it hasn’t taken off and gone anywhere yet. Many thanks. Ian.

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Oscar 11th March 2020 - 8:51 pm

you are too close, it has to be at least certain distance from the launch location (set in the CLI commands)

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trex450 26th January 2020 - 9:12 pm

hi oscar, thank you very mutch for the description. it works fine.
for eachine x220hv @4s it is very important to change the default values form this parameter to:

gps_rescue_throttle_hover = 1400
gps_rescue_throttle_min = 1250

otherwise the drone fly back in rescue-mode like a frog. the motor seams to stopp every second an then start again and so on. this because the default value (1280) is to low for hovering. also the …trotte_min ist too low. you have to determine this paramter for your own drone.

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Bill 13th January 2020 - 6:22 pm

Great write-up Oscar! Thank you. I set mine up but when it reached 100m from home it shut-off motors and crashed. :( Any suggestions?

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Oscar 22nd January 2020 - 12:45 pm

because you set distance to 100m? you should just take over control as soon as you have signal, it’s not designed to return to home like DJI drones.

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Ditto 12th January 2020 - 2:12 pm

Hi Oscar,

Bravo !!! This blog is great,

Pls Help I’m still confuse and had a question when GPS rescue set with the fail safe logic not using switch as per below,

set failsafe_procedure = GPS-RESCUE

save

I know it will happen “automatically” during e.g rx loss…, and after the rx signal back to normal what will happen with fail safe procedure? can I control back my quad or let it land? under authority of failsafe?

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Oscar 13th January 2020 - 4:45 pm

You will regain control as soon as signal is back. Please read the section “Using GPS_Rescue for Failsafe” again, it tells you how it works and how it should be setup.

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Willy 11th December 2019 - 1:14 pm

I ask you a question, does the GPS on the drone help stabilize it, kind of like dji that when they are with connected satellites are stuck in a place?

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Jovan 30th September 2020 - 5:51 am

I believe gps rescue only helps you get back your quad not stabilise it at least in betaflight

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Willy Arredondo 11th December 2019 - 1:12 pm

Te hago una consulta el gps en el dron lo ayuda a estabilizarlo, tipo casi como los dji que cuando estan con suficientes satelites conectados se quedan clavado en un lugar ?

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David Downs 7th December 2019 - 10:58 pm

Oscar question how would I have gps rescue on a switch and also have my Fail-Safe set to either work like normal no gps rescue and have gps rescue activate when wanted on the same switch? Just in case I have rx loss in a bad area I don’t want it to activate GPS rescue like a bando spot or low clearance area…so I wanna have the betaflight Fail-Safe to be setup with a switch but have two options for Fail-Safe on a switch and a sepy switch for gps rescue all by itself? Is this possible?

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Aditya 14th August 2019 - 6:51 am

Hi Oscar,

Many thanks for sharing this…. Test the GPS rescue with switch and works great.

Pls advice which failsafe mode i should choose in TX? I am using Tarani Xlite with r9 lite module. Should i just put “no pulse” or make it “Custom” and than set to activate GPS Rescue switch.

Thanks before

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Oscar 29th August 2019 - 10:45 pm

it shouldn’t matter as long as you use SBUS or FPort, because it has a failsafe flag in the protocol to notify the FC, but setting it to no pulse is probably the safest.

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Olivier Hacking 1st July 2019 - 10:12 am

This looks great, thanks for the report. I lost video above a river last weekend and almost lost the quad… Luckily video came back.
However, I am running a full KISS (V1) setup. Is it possible to setup such a system on a KISS quad?

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Oscar 15th July 2019 - 4:13 pm

Not unless KISS support GPS. You’d have to check with KISS customer service, I am not sure if this is possible.

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Daniel 29th May 2019 - 8:04 pm

Hello Oscar!

How i need to set my failsave in crossfire, should i set it to cut, and in betaflight to gps rescue? is this ok? i use betaflight 4.0, and rth on a switch works perfect.

Thanks for Help!

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Oscar 30th May 2019 - 5:20 pm

Yea sounds good to me.

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John S 14th May 2019 - 2:56 am

To add some feedback, in case it helps others: Adjust `gps_rescue_angle` with caution!

The default GPS Rescue Mode variables tested correctly on my 7″ SuperG+ running Betaflight 3.5.7. I sometimes fly during moderate wind where 32 degrees of pitch is insufficient, so I increased `set gps_rescue_angle` from 32 to 40 degrees. During testing, however, gps_rescue_angle=40 consistently caused the quad to reach altitude, then descend towards 0 altitude as it headed towards home (well before reaching `gps_rescue_descent_distance`). The quad would have crashed into the ground had I not taken control. I tried 4S, 5S, and 6S batteries with the same results. Increasing `gps_rescue_throttle_max` from 1600 to 1800 did not help. This is odd, as the quad is well tuned and I have no problem maintaining altitude when flying at a 40+ degree pitch.

All is well with gps_rescue_angle=32. Hopefully it’s not too windy when I need a rescue!

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TDub 9th April 2019 - 7:47 am

@jerrod I have gps mode enabled. I know this because I can see my long and lat on my OSD. I can see how many gps satalights im locked into.

But when I go into modes there is no rescue mode. It’s as if my version doesn’t support it but I’m using 3.5.6 and every guide says 3.5+.

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Jerrod 4th April 2019 - 6:07 am

@Tdub – in your config tab you have to enable GPS mode. Almost exactly half way down the page, on the right column.

@Oscar – I think you might have it backwards. My gps return to home works the other way – up arrow is toward home, down arrow means you’re traveling away from home.

Thanks for the article Oscar!

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Oscar 8th April 2019 - 5:33 pm

That’s what i mean exactly.

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TDub 13th March 2019 - 4:24 am

I’ve set up a GPS module via an open port. I have it communicating, I can see my GPS stats on my OSD but when I go into “modes” I do not have a “GPS Rescue” option. I have “Beep GPS Satellite Count” but no rescue mode. How do I enable that mode?

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James Hatton 11th March 2019 - 3:49 am

Hi, I set my Cl Racing F4S board and HGLRC Neo-8M GPS up exactly the way you wrote. I made a simple flight
in the front yard. The quad was only about 5 feet off the ground and flew out about 35 feet, stopped, turned around but all of a sudden it went full throttle and shot up only to either I killed the motors or the motors quit and it fell to the pavement nose first. (miraculously there was no damage except the ice that it hit) I have no idea what caused that to happen.
Now when I got the quad in the air again I didn’t touch Rescue or anything and as the quad was hovering in front of me the motors suddenly quit and it fell to the ground. I was informed that maybe the quad is going into failsafe mode. The board is new as is the Rx, was a clean build and everything is working.
I now understand that Rescue if activated closer than 100m will kill the motors but what happens if you are coming back on Rescue will it kill the motors when it comes within the 100m?

https://www.youtube.com/watch?v=BWmHsctdpck&t=1s

Thank you, your information is very valuable to us.
Jim

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Trevor Crouch 15th February 2019 - 5:34 pm

Hi Oscar (or anyone else, that can help) Ive type in get gps in the cli and I dont have set gps_rescue_min_dth = 100. If I try to add it in it comes back with ###ERROR### Invalid name. Is there a clever way of adding this command into the B/F 3.5.1 thats on my G730L please? Im stumped :(

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Oscar 25th February 2019 - 4:25 pm

This command is for the future version of Betaflight 4.0 (still in Beta).
For current stable Betaflight 3.5.X, use this command instead:

set gps_rescue_min_descent_dist = 100

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Richard 4th March 2019 - 11:12 pm

I have tried both commands and am getting the invalid name on both. I have betaflight 3.5.6 installed. Any other recommendations?

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Oscar 11th March 2019 - 4:07 pm

can you try “get gps_rescue_” and try find it?

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Lee 7th January 2019 - 3:18 pm

Hi Oscar, one question to ask ,
If I set failsafe on my transmitter for quad to power down the motors and drop , and I was to set up gps RTH as failsafe also ,
Question, what failsafe will the quad take orders from ?
Will it drop or RTH?
Thank you Oscar I’m learning a lot for your blog
Very new to the hobby

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Oscar 10th January 2019 - 3:21 pm

look at these as layers… TX, RX and FC, these are all layers.
The closest layer to your motors is the FC, so the quad will react to the FC failsafe layer first.
This is assuming you are using SBUS or CRSF, where the RX will send a “Failsafe flag” to the FC.

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Robert 29th December 2018 - 2:59 pm

home arrow in Betaflight OSD says wrong direction and when turn on rescue going away from me——-why

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Oscar 1st January 2019 - 12:12 pm

not enough satellites? Or GPS module is interfered by VTX? Try further separation.

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Brad Ivie 26th December 2018 - 6:48 pm

Hello Oscar! I have a question and think may know now but want to MAKE SURE…For the first trial with the rescue mode has me puzzled but I think that may be clear now as well…. Okay first time I tried it, it seemed to start to work, it went straight up I guess the the altitude have set but then dropped from the sky?! Now I think that is prob due to I turned GPS Rescue back off then tried to turn it back on, and after reading your article that seems to make it drop??…I think? as well as I “may” have disarmed it and rearmed it to try to get the “failsafe” rescue to kick in and prob re-set the “home” location?! Alright I am about to try it again now after doing some adjusting, BUT MY BIG question is “Which way should the arrow point for home” down?? For if I remember correctly I did watch someones video on this after my failure, and I believe and PLEASE TELL ME, when arrow is pointing downward is that pointing to “home” for I just flew it and seems that was direction it was when I was some distance away, and in the video I watched I DID notice that when rescue is activated the arrow JUMPS STRAIGHT UP on it’s return, so I still am confused?!! So which way should the arrow be pointing when I have it away from me and should be pointing “home”?? PLEASE let me know for need to test it again, but I almost lost it the first time just got lucky finding it somewhat. Thanks I greatly appreciate it!

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Oscar 1st January 2019 - 11:44 am

If the arrow points up in OSD, means it’s flying away from home. If it points down, it means the quad is facing home.

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gino 20th December 2018 - 1:24 pm

please could you help I have put gps on my quad tested it in my garden with props off so got 8 sats come up when I flicked the switch the motors go very fast ,my question is why should it do this when it is not 100 m away ,should it have gone into failsafe and cut the motors ,I have set all the cli commands as you have and am running 3.5.1

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Gordon 15th November 2018 - 8:30 am

Hi Oscar, would you know why I can get Rescue mode to work faultlessly when I activate it with a switch but when I try to activate it with failsafe either with Failsafe set to a switch or by turning off the transmitter it just disarms.

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Oscar 23rd November 2018 - 4:35 am

Rescue mode only works when the quad is further than 100m away (or any distance you set), within this distance you quad will just drop/disarm.
If this is not the case then you need to play with Insanity-Check’s options.

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Tavis 24th October 2018 - 8:15 pm

When testing GPS Rescue, make sure you land and disarm between tests. This is because the rescue altitude is set to the highest altitude you reach during flight or the minimum setting number (whichever is greater, ie. the quad will never descend when rescue is activated, it will only ascend or maintain altitude). If you do multiple rescue tests without disarming, then the minimum altitude can stack higher and higher depending on how high you are flying and each test the quad will climb a little bit higher due to the altitude error stacking.

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Fei 24th October 2018 - 3:34 pm

Thanks for explaination!
What will drone doing when he returns to home, will it land automatically and disarm? For example if i have problems with radio.

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VAlex 6th December 2018 - 2:41 pm

No, it will not land but drop. Make sure to regain control.

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Steve Matthews 24th October 2018 - 12:52 pm

Does anyone know whether this is possible using a FRSky GPS module? I have a feeling it’s not, and that the FrSKy only connects to the FrSky receiver not directly to the flight controller.

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Olumuyiwa Alao 24th October 2018 - 3:52 am

Hello Oscar. Thank you for the wonderful post.

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Jacob Alao 24th October 2018 - 3:18 am

Hi Oscar. Thank you so so much for this information. I have a question based on the last section of your blog. If I set Gps rescue to failsafe and I experience failsafe and lose video at the same time. My quad starts heading back and it reconnects to my quad, but I am flying blind. U said set the switch to failsafe as well. How do I set both up, failsafe and switch if I can only chose one mode. Please advice. Thank you. I have learnt a lot.

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Oscar 6th November 2018 - 12:29 pm

Setup GPS Rescue mode on a switch, so when failsafe happens, you should also flip the GPS Rescue mode switch.

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Roger 24th October 2018 - 12:52 am

Good information Oscar. I installed mine a couple of weeks ago (mini ublox M8N) strictly for lost quad location. I went out to check it out but due to a FC malfunction my quad went wildly out of control before i had a chance to ‘test’ the install. Long story short, got my GPS coordinates from my DVR, plugged them into my smartphone and it got me within 50 feet of my quad. :) With out the GPS i probably would have been hours trying to find the quad.

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Oscar 6th November 2018 - 12:23 pm

that’s good to hear bro!

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Ashade 23rd October 2018 - 5:31 pm

I have experience the “drone falling out of the sky” issue. My question is: Why would sanity check make the quad behave properly when it doesn’t do that by arming through a switch. Have you test that? I have sanity check off because of this reason as of right now.

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Oscar 6th November 2018 - 12:18 pm

it’s really a hit and miss issue at the moment with Sanity Check. Make sure you understand the risk of turning it off. Sometimes it’s better to lose your quad than damaging something or someone more important.

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Eli 23rd October 2018 - 10:01 am

Hi Oscar ! there’s one important detail in:
set gps_rescue_initial_alt = 50

where 50 is Alt in meters. this value means Absolute alt or above takeoff ?
because in my place Absolute hight ( ground level ) is about 180 meters so if I write 50 meters my drone becomes a suicide machine )))

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Oscar 23rd October 2018 - 5:25 pm

It’s the height from ground :) so setting that to 50 would be 230m in your cause

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WP 20th October 2018 - 10:03 pm

Hi Oscar,

non-failsafe scenario question:
is it possible to take back the control if the mode was activated previously w. a switch?

If I turn the mode off w. the switch within the minimum range (before the quad “lands”) it falls from the sky.

BF3.4

thanks,
WP

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Oscar 23rd October 2018 - 5:17 pm

Yea if it was activated with a switch, you can put it back in acro mode anytime using that switch. What’s your Sanity setting?

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Pablo 20th October 2018 - 6:47 pm

Thanks for this post! My next build will probably be a 6inch for mid/long range with gps, so this tutorial it’s perfect

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Mad Monkey FPV 20th October 2018 - 12:39 pm

When I first tested this (less than descent distance) it just disarmed in flight.Does any modification beed to be made to the sanity checks tonprevent this?

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Oscar 23rd October 2018 - 5:07 pm

You can try
set gps_rescue_sanity_checks = RESCUE_SANITY_FS_ONLY
or even OFF, but that’s not recommended according to the wiki.

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Dave 24th October 2018 - 6:44 pm

You need to be beyond the minimum range of 100m, maybe its set as part of descent distance, not sure on that. The disarm I believe is a safety measure so the drone doesn’t fly autopilot straight into you being so close to its home coordinates. Personally I would like to see a safety check added that if it is activated by switch within the 100m range, it simply does nothing but beeps an alarm onscreen “proximity” or something instead of dropping out of the sky.

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