Platform: Pixhawk 2.4.8 Firmware: ArduCopter 4.6.3 Frame: F450 Quadcopter, QUAD/X configuration RC: FlySky FS-i6 transmitter with FS-iA6B receiver via PPM encoder GPS: NEO-M8N connected to GPS and I2C ports ESCs: HP 30A ESCs Motors: A2212 1000KV
Issue: Safety switch is connected to the SWITCH port. When pressed it transitions to fast blinking indicating it is active. However the HUD in Mission Planner reverts to showing SAFE and (safety) shortly after, indicating the system is returning to safe mode.
Symptoms:
Motor Test in Mission Planner returns “Command Denied by Autopilot” with message log showing “Motor Test: Safety switch”
Drone can be armed via Mission Planner Actions tab but HUD immediately reverts to showing SAFE and (safety)
Motors do not respond to throttle input when armed
All 4 ESCs beep on startup confirming power
All 4 motors twitch on startup confirming signal is reaching ESCs
Note: All parameters have been reset to default values. No custom parameter changes are currently active.
Question: Why does the safety switch revert to SAFE mode after fast blinking and how do we permanently disable or correctly configure the safety switch behavior on ArduCopter 4.6.3 with Pixhawk 2.4.8? Is this a known issue with this firmware version on this hardware?
which is good because who wants to reach in amongst spinning props to press a “SAFETY” switch?
If anyone is worried about a copter not disarming, or crashing set up Emergency Motor Stop - I use channel 13 set to RC Option 31 (easy to remember). Great during testing phases, especially for large expensive copters.
I am using the safety button that was included in the Pixhawk PX4 2.4.8 kit. It is the standard Pixhawk safety switch that came bundled with the flight controller, connected to the SWITCH port on the Pixhawk. It is not a third party or aftermarket switch — it is the OEM safety button included in the package. I do not have a specific make or model number for the switch beyond it being the standard Pixhawk 2.4.8 bundled safety button.
As the Pixhawk 2.4.8 mostly are some clones so also the switch what ever it is will be not OEM. So please show your switch with detailed photos and show a link to the product side you have bought
Yea, as @Juergen-Fahlbusch said there are no real “OEM” Pixhawk 2.4.8’s as there was never an official one. They are component reduced generics from unknown manufactures’s.
But, of all the poor quality and unsuitable for multirotor parts you have it’s the most serviceable.
This link shows no details.
Check if the safety button is only a button or if it is a real switch.
Otherwise follow Shawn’s recommendation and disable the function at all
I would not have suggested that kit of parts. A TBS Lucid H7 with a TBS Lucid 4-in1 ESC would be ~$155 from US domestic sources. The M8N is old tech, you want an M10 (~$25 depending on which module). You would not need a power module, nor any of that other junk. The generic telemetry radios can be trouble but they will probably work. Branded ones from HolyBro would be preferable. A bit more money but not a lot more for up to date quality hardware.
I have written the following parameters: BRD_SAFETY_DEFLT = 0 and BRD_SAFETYOPTION = 0.
After making these changes, the Motor Test no longer returns “Command Denied by Autopilot” for Motors A, B, C, and D. However, there is still no motor response during the test.
I was able to arm the drone via the Actions menu in Mission Planner and the HUD confirmed the status as ARMED. With the drone armed, I attempted to control the motors using the FlySky transmitter but received no motor response.
Subsequently, the Actions menu is no longer allowing the drone to arm and shows the message “DISARMED”. No error message was provided explaining why arming is being refused.
I previously had the motor test throttle % set to 5%. I increased it to 50% to understand the impact. There is no measurable change to the behavior of the motors when testing. The FlySky throttle increase does not create any new behavior either.
Interestingly, I am able to arm the drone from the actions menu, yet it immediately disarms. I have posted the log below.
3/14/2026 9:25:54 AM : Arm: LAND mode not armable
3/14/2026 9:25:43 AM : finished motor test
3/14/2026 9:25:41 AM : starting motor test
3/14/2026 9:25:23 AM : finished motor test
3/14/2026 9:25:21 AM : starting motor test
3/14/2026 9:25:18 AM : finished motor test
3/14/2026 9:25:16 AM : starting motor test
3/14/2026 9:25:00 AM : Arm: LAND mode not armable
3/14/2026 9:24:39 AM : Arm: LAND mode not armable
3/14/2026 9:24:34 AM : EKF3 IMU0 MAG0 initial yaw alignment complete
3/14/2026 9:24:34 AM : EKF3 IMU0 tilt alignment complete
3/14/2026 9:24:32 AM : EKF3 IMU0 initialised
3/14/2026 9:24:32 AM : EKF3 IMU0 forced reset
3/14/2026 9:24:20 AM : Arm: LAND mode not armable
3/14/2026 9:24:03 AM : Radio Failsafe Cleared
3/14/2026 9:24:03 AM : Mode change to RTL failed: requires position
3/14/2026 9:24:03 AM : Radio Failsafe
3/14/2026 9:23:49 AM : Warning: Arming Checks Disabled
3/14/2026 9:23:40 AM : finished motor test
3/14/2026 9:23:38 AM : starting motor test
3/14/2026 9:23:37 AM : Radio Failsafe Cleared
3/14/2026 9:23:37 AM : Radio Failsafe - Disarming
3/14/2026 9:23:34 AM : finished motor test
3/14/2026 9:23:33 AM : starting motor test
3/14/2026 9:23:32 AM : Radio Failsafe Cleared
3/14/2026 9:23:32 AM : Radio Failsafe - Disarming
3/14/2026 9:23:31 AM : Radio Failsafe Cleared
3/14/2026 9:23:31 AM : Radio Failsafe - Disarming
3/14/2026 9:23:30 AM : finished motor test
3/14/2026 9:23:28 AM : starting motor test
3/14/2026 9:23:25 AM : finished motor test
3/14/2026 9:23:23 AM : starting motor test
3/14/2026 9:23:19 AM : finished motor test
3/14/2026 9:23:18 AM : starting motor test
3/14/2026 9:23:09 AM : GPS 1: u-blox saving config
3/14/2026 9:23:04 AM : u-blox 1 HW: 00080000 SW: ROM CORE 3.01 (107888)
3/14/2026 9:23:00 AM : GPS 1: detected u-blox
3/14/2026 9:23:00 AM : GPS 1: probing for u-blox at 230400 baud
3/14/2026 9:22:55 AM : Frame: QUAD/X
3/14/2026 9:22:55 AM : IMU0: fast sampling enabled 8.0kHz/1.0kHz
3/14/2026 9:22:55 AM : RCOut: PWM:1-14
3/14/2026 9:22:55 AM : IOMCU: 0 0 411FC231
3/14/2026 9:22:55 AM : Pixhawk1 0032003F 3533510F 33383331
3/14/2026 9:22:55 AM : ChibiOS: 88b84600
3/14/2026 9:22:55 AM : ArduCopter V4.6.3 (92b0cd78)
3/14/2026 9:22:55 AM : Frame: QUAD/X
3/14/2026 9:22:55 AM : IMU0: fast sampling enabled 8.0kHz/1.0kHz
3/14/2026 9:22:55 AM : RCOut: PWM:1-14
3/14/2026 9:22:55 AM : IOMCU: 0 0 411FC231
3/14/2026 9:22:55 AM : Pixhawk1 0032003F 3533510F 33383331
3/14/2026 9:22:55 AM : ChibiOS: 88b84600
3/14/2026 9:22:55 AM : ArduCopter V4.6.3 (92b0cd78)
3/14/2026 9:22:54 AM : Frame: QUAD/X
3/14/2026 9:22:54 AM : IMU0: fast sampling enabled 8.0kHz/1.0kHz
3/14/2026 9:22:54 AM : RCOut: PWM:1-14
3/14/2026 9:22:54 AM : IOMCU: 0 0 411FC231
3/14/2026 9:22:54 AM : Pixhawk1 0032003F 3533510F 33383331
3/14/2026 9:22:54 AM : ChibiOS: 88b84600
3/14/2026 9:22:54 AM : ArduCopter V4.6.3 (92b0cd78)
That’s not a log. The log is a .bin file saved on the Flight Controller. Download it, put it on a file storage service and post a link to it. Downloading and analyzing logs
And enable all arming checks.
And you will probably have to provide some some photos of how things are connected to the FC.
