What happened
On April 28, 2014, at approximately 11:47 JST, an Airbus A320-214, registered JA802P, operated by Peach Aviation Co., Ltd., was conducting a precision approach to Runway 18 at Naha Airport. The flight, operating as scheduled Flight 252 from New-Ishigaki Airport, was being guided by precision approach radar.
During the approach, the aircraft began an unplanned descent. As the plane reached a position roughly 4 nautical miles north of the airport at an altitude of approximately 300 feet, the Enhanced Ground Proximity Warning System (EGPWS) issued several alerts, including "TOO LOW" and "TERRAIN" warnings. To prevent a potential collision with the water surface, the captain executed an emergency go-around. The aircraft subsequently completed its landing at Naha Airport at 12:10. There were 59 persons on board (including 53 passengers and 6 crew), and no injuries or damage to the aircraft were reported.
The investigation
The JTSB investigation examined flight data recorder (FDR) records, cockpit voice recorder (CVR) transcripts, and air traffic control (ATC) communications. The inquiry focused on the sequence of altitude deviations, the crew's monitoring of the autopilot system, and the effectiveness of the radar safety zone protocols at the Naha Ground Controlled Approach Facility. The investigation also reviewed the aircraft's instrument settings, specifically the vertical speed (VS) knob operations, and the communication between the pattern and final controllers.
Findings
- The unplanned descent was initiated by an unintentional operation by the captain.
- The crew failed to maintain adequate altitude monitoring because they relied too heavily on the autopilot system and did not properly prioritize their flight tasks.
- There was insufficient risk management at the Naha Ground Controlled Approach Facility, specifically regarding the identification of the aircraft before it deviated below the Radar Safety Zone.
- The pattern controller had notified the final controller that the aircraft was descending, but the descent continued into a critical altitude range.