Which device prevents gear retraction on the ground?

• A. Squat switch
• B. Altitude switch
• C. Pressure switch
• D. Temperature switch

Answer: (A)

Weight-on-wheels sensing controls whether the gear can retract. A squat switch, mounted on the landing gear or its strut, is activated by the compression of the oleo when the aircraft sits on the ground. When weight is on the wheels, the switch signals the gear control to inhibit retraction, keeping the gear down and locked. Once the aircraft leaves the ground and weight is off the wheels, the switch changes state and the gear retraction sequence can proceed. Other switches like altitude, pressure, or temperature serve different functions in the aircraft’s systems and do not provide the ground-weight signal needed to prevent gear retraction on the ground.