What happened
During the initial approach phase, the crew of a Boeing 747-200 observed the red gear annunciator light and heard the landing gear warning horn after extending the flaps to 25 degrees and moving the gear lever to the down position. During the subsequent go-around, the captain inquired about the status of the gear lights, to which the second officer replied that there were four lights visible. On this specific aircraft model, a fully extended and locked gear configuration should display five green lights on the second officer's instrument panel.
In an attempt to resolve the issue, the crew performed the "Red Gear Light Remains On (After Gear Extension)" emergency procedure. Although the checklist explicitly stated in boldface that five lights must be present to confirm the gear was down and locked, the crew failed to verbalize this specific requirement. Instead, the crew used vague terminology, such as "all gear" or "all green," and did not perform a specific count of the illuminated lights. Because the crew incorrectly believed the gear was fully locked, they opted not to recycle the gear or use alternate extension systems before attempting a second approach.
Furthermore, the crew did not inform air traffic control of the specific landing gear warning they were managing. This lack of communication prevented controllers from potentially alerting the crew to the nose gear's status during the approach.
Findings
Investigations revealed that the crew's failure to verbally confirm the specific number of green lights during the checklist procedure led to the incorrect assumption that the gear was secure. While a post-accident inspection of the nose gear door actuator showed that one of the two lock keys had been installed 180 degrees backward, this component had been part of the aircraft since a 2001 overhaul. Subsequent testing showed that the nose gear could extend properly with all correct indications. No mechanical faults were found within the landing gear indication module, the nose gear-operated door sequence valve, or the selector valve.