Global Position Unknown - Fixed Bank Loiter

Owned by Matt Skelton
Last updated: Apr 04, 2023
2 min read

What triggered the failsafe?

The aircraft global position accuracy has exceeded the allowable threshold. The aircraft no longer trusts its ability to know where it is in the world. This can be due to the following:

Cause

Info

Cause

Info

Poorly connected wing 

  • The wing was not properly attached to the fuselage. The wing could have been loose of not fully seated. Using wing pins help confirm that the wing is properly attached.

  • The spar joiner was broken, compromised, or missing. The spar joiner transfers aerodynamic forces from the wing to the fuselage. If the spar joiner is damaged or missing the forces can't properly be transferred and the wing may become electrically and mechanically disconnected.

Poor GPS quality 

The GPS did not have an accurate fix. This can be due to location conditions. The GPS needs a clear view of the sky to perform as expected. Trees, buildings, vehicles, and other large obstructions can block the GPS signal from the aircraft.

Un-calibrated aircraft sensors (usually compass/magnetometer)

The aircraft's ability to know where it is not solely based off of GPS signal. Other sensors such as the compass/magnetometer have an influence on the positional accuracy. A poorly or un-calibrated compass can contribute to triggering this failsafe.  

Extreme Temperature Conditions

Flying outside of the listed aircraft temperature limits can cause the autopilot sensors to experience thermal offsets that lead to degraded positional accuracy.

What will the aircraft do?

The aircraft will enter a turn at its current location. The motor will then turn off and the aircraft will circle down to the ground.

What should the pilot do?

The pilot should visually find the aircraft in the sky and monitor where the aircraft circles down. Identify landmarks (if available) and use them for finding the aircraft once it has come to a stop. The location shown on the Fly PHX map is NOT a good indicator of the aircrafts last know position. This is because the last reported positions are near the accuracy threshold and thus they are not accurate, rather a slightly educated guess. Using your eyes is MUCH more reliable.Â