What system is responsible for preventing gear retraction on the ground?

The system responsible for preventing gear retraction on the ground is the squat switch. The squat switch is a critical safety feature that ensures the landing gear remains in the down and locked position while the aircraft is on the ground. When the aircraft is sitting on its gear, the squat switch is activated, indicating to the aircraft's system that it is on the ground. This prevents the landing gear from retracting inadvertently while the aircraft has not yet taken off and ensures safety during ground operations.

When the aircraft becomes airborne and the wheels leave the ground, the squat switch deactivates, allowing the gear retraction system to function normally for takeoff. This design helps prevent accidents that could occur if the gear were to retract while the aircraft is still on the runway or taxiway. Other options, though they may relate to different aircraft systems, do not specifically perform this function. For instance, weight sensors may detect load but don’t necessarily control gear position, while proximity and pressure switches are used in other contexts that don’t directly affect landing gear retraction on the ground.