Which inputs determine the Air/Ground status?

• A. LH and RH gear switches, radar altimeters, and the CAS from ADAHRS
• B. LH gear switches only
• C. Radar altimeters only
• D. GPS signal data

Answer: (A)

Air/Ground status is determined by combining multiple, independent signals so the system can reliably know whether the airplane is on the surface or in the air. The primary inputs are:

• The gear switches on both sides tell the system whether the landing gear is down and locked or up. This is a direct physical indicator of being on the ground or not, and both sides are used for redundancy and accuracy.

• The radar altimeter provides a direct measurement of height above the terrain. When the radar altitude is near zero (and other data align), the system can confidently classify the aircraft as on the ground, especially during approaches and after landing.

• The CAS from the ADAHRS supplies air data such as altitude, vertical speed, and other attitude/flight information. This helps confirm whether the aircraft is in flight or transitioning to the ground state, and it provides a check against gear or radar altimeter inputs if one source is unreliable or ambiguous.

GPS data is not used to determine Air/Ground status because it does not directly indicate contact with the surface or height above terrain, which is what drives this classification.