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Analysis

Summary

During the first landing, the nosewheel remained airborne throughout the landing sequence, indicating that de-rotation did not occur. Consequently, the front wheels of the main landing gears probably did not contact the ground for a sufficient period to allow them to accelerate to the required wheel speed condition. That resulted in the logic conditions for ground spoiler deployment not being met. Those required compression of both left and right main landing gears ('weight on wheels'), and a radio altitude of less than 6 ft or a wheel speed greater than 72 kts on the front and aft wheels of the main landing gears. Without a valid radio altitude signal of less than 6 ft, and without ground spoilers deployed, the logic conditions for reverse thrust were also not met, and it too was unavailable. The absence of an AP OFF INVOLUNTARY WARNING indicated that the crew had intentionally disconnected the autopilot during the approach.

The loss of valid radio altimeter signals did not result in the automatic switching from flight mode to flare mode when the autopilots disengaged. That was due to the water ingress into the radio altimeter antennas, and which resulted in the radio altimeter signals being interpreted as out of range signals, rather than as a failure of the radio altimeters.

 
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