opened 03:48AM - 06 Dec 23 UTC
bug-report
### Describe the bug
The pilot (i.e., GCS operator) executes missions by settin… g waypoints for the drone. In the event that the operator moves the Home point while the drone is en route to any waypoint and subsequently re-executes the mission, a vulnerability is triggered. This vulnerability can result in inaccurate altitude determination during the flight, leading to unexpected descent or ascent, deviating from the intended mission altitude set by the operator. Such altitude anomalies have the potential to cause serious consequences, including drone crashes or the occurrence of hazardous incidents.
Maybe the relative altitude of the mission should be based on the initial Home point's altitude, which is set as a constant value. Even if the Home point is moved, it should not affect the altitude settings of the mission.
### To Reproduce
1. The operator begins by plotting the mission path, setting the expected altitude to 10m (a smaller value to increase the likelihood of triggering a crash). The first waypoint (takeoff point) is intentionally placed at a location different from the drone's initial position. Note: According to PX4 specifications, when the takeoff point is not at the same location as the drone, it is considered the first waypoint of the mission.
2. The operator manually initiates the drone takeoff.
3. The operator relocates the Home point to a position with an altitude lower than the current Home point's altitude (it is easy to overlook the altitude setting during the actual adjustment). Let the difference between the original Home altitude and the current Home altitude be denoted as X meters.
- X ≥ 10m (expected altitude) → Drone crash
- 0 < X < 10m (expected altitude) → Drone flies below the expected altitude
- X < 0m → Drone flies above the expected altitude
4. The operator proceeds to execute the mission.
5. The drone follows the mission, flying towards the first waypoint. During the execution, the drone experiences a descent due to the fact that the mission's altitude is relative to the current Home point's altitude. This descent ultimately leads to a ground collision.
### Expected behavior
- X ≥ 10m (expected altitude) → Drone crash
- 0 < X < 10m (expected altitude) → Drone flies below the expected altitude
- X < 0m → Drone flies above the expected altitude
Our experiment resulted in the drone crashing to the ground
### Screenshot / Media
### Flight Log
[02_43_15.zip](https://github.com/PX4/PX4-Autopilot/files/13575576/02_43_15.zip)
### Software Version
HW arch: PX4_SITL
PX4 git-hash: 9d465615d11ab4b570a66da22a3681f56679a317
PX4 version: 1.15.0 40 (17760320)
PX4 git-branch: main
OS: Linux
OS version: Release 5.15.0 (84869375)
Build datetime: Nov 30 2023 15:12:54
Build uri: localhost
Build variant: default
Toolchain: GNU GCC, 9.4.0
PX4GUID: 1006554d49534954414c44494e4f30303030
### Flight controller
SITL
### Vehicle type
None
### How are the different components wired up (including port information)
_No response_
### Additional context
_No response_
Hello ,guys.We found that modifying the home point while executing a mission could potentially cause the mission to execute abnormally, and wondered if you guys think this is a logic flaw. Looking forward to your comments!
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