Plain English Meaning

Something has gone wrong with the wheels-and-struts system that lowers and locks the gear for landing. The gear may not come down, may not lock down, may not retract, or may not show a safe indication in the cockpit.

Full Definition

A failure of the landing gear system to operate as designed, including failure to extend, failure to retract, partial extension, asymmetric extension, unsafe indication, or collapse on touchdown. Causes can be mechanical (broken linkages, hydraulic loss, electrical failure), procedural (mis-selected position, circuit breaker tripped), or environmental (ice, debris in the wells).

Context Anchor

Encountered during or retraction, especially when checks that the landing gear is .