3.2 CAUSES[CONTRIBUTINGFACTORS]
The flight crew did not comply with Air Niugini Standard Operating Procedures Manual (SOPM) and the approach and pre-landing checklists. The RNAV (GPS) Rwy 04 Approach chart procedure was not adequately briefed.
The aircraft’s flight path became unstable with lateral over-controlling commencing shortly after auto- pilot disconnect at 625 ft (677 ft). From 546 ft (600 ft) the aircraft was flown in Instrument Meteorological Conditions (IMC) and the rate of descent significantly exceeded 1,000 feet/min in Instrument Meteorological Conditions (IMC) from 420 ft (477 ft).
The flight crew heard, but disregarded, 13 EGPWS aural alerts (Glideslope and Sink Rate), and flew a 4.5o average flight path (glideslope).
The pilots lost situational awareness and their attention was channelised or fixated on completing the landing.
The PIC did not execute the missed approach at the MAP despite: PAPI showing 3 whites just before entering IMC; the unstabilised approach; the glideslope indicator on the PFD showing a rapid glideslope deviation from half-dot low to 2-dots high within 9 seconds after passing the MDA; the excessive rate of descent; the EGPWS aural alerts: and the EGPWS visual PULL UP warning on the PFD.
The copilot (support/monitoring pilot) was ineffective and was oblivious to the rapidly unfolding unsafe situation.
It is likely that a continuous “WHOOP WHOOP PULL UP”70 hard aural warning, simultaneously with the visual display of PULL UP on the PFD (desirably a flashing visual display PULL UP on the PFD), could have been effective in alerting the crew of the imminent danger, prompting a pull up and execution of a missed approach, that may have prevented the accident.
3.3 OTHERFACTORS
This is used for safety deficiencies or concerns that are identified during the course of the investigation that while not causal to the accident, nevertheless should be addressed with the aim of accident prevention.
The investigation found a number of non-contributory safety deficiencies. These are addressed in Part 1 Factual and Part 4 Safety actions and recommendations.
3.4 USNTSBSTATEOFMANUFACTURECONCLUSIONS
The US National Transportation Safety Board’s Accredited Representative and Technical Advisers representing the State of Manufacture, had full access to the evidence, including all recorded data and the cockpit imagery (video), in accordance with Annex 13 international obligations.
The NTSB team provided their conclusions, which have been duly considered during the drafting of the Final Report.
With respect to the last paragraph of Section 3.1 above, the NTSB Team requested that the substance of their comments be appended to the Final Report, in accordance with Paragraph 6.3 of Annex 13, Standard.
The AIC agreed to publish the NTSB Team’s findings and conclusion, which states:
NTSB staff disagrees that an additional warning would have been effective in alerting the crew. The conclusions and the supporting information in the draft report effectively demonstrate that the pilots:
• Lost situational awareness.
• Disregarded 16 EGPWS alerts that had occurred in the 19 seconds preceding impact with
the water.
• Disregarded vertical guidance being displayed on the Primary Flight Display (PFD).
• Did not comply with the Air Niugini go-around policy after the first and subsequent EGPWS alerts.
• Did not comply with the Air Niugini go-around policy after the approach had become unstable with the descent rate exceeding 1000 feet per minute.
NTSB staff believes that the actions of the pilots to disregard the 16 EGPWS alerts and to not comply with Air Niugini policy clearly demonstrate that the crew was unresponsive to guidance that should have prompted a clear and decisive action to initiate a missed approach.
NTSB staff believes the disregard of the alerts, disregard of the PFD display guidance, and the continuation of an unstable approach demonstrate that any additional guidance, alert, or warning would be similarly disregarded by the flight crew and ineffective in preventing the accident.