Air Nuigini’s flight crew ignored danger warnings, contributing to the aircraft accident that killed one passenger and injured six others in Chuuk last year, according Papua New Guinea’s Accident Investigation Commission.
Investigation found “that there were no issues with the aircraft and all systems were generally operating normally” before it crashed into the lagoon off Weno airport, according to the report which attributed Flight 73's ill fate to the crew’s failure to follow rules and standards.
With 12 crew members and 35 passengers on board, Air Nuigini’s Boeing 737 took off from Pohnpei and crash-landed into the water on Sept. 28, 2018 about 1,500 ft short of the runway threshold during the final landing approach.
“The flight crew did not comply with Air Niugini Standard Operating Procedures Manual and the approach and pre-landing checklists,” states the commission’s report released Thursday.
Investigation found that the cockpit voice recorder information received a total of 13 aural alerts, which the flight crew disregarded and “did not acknowledge the ‘minimums’ and ‘100 ft’ advisories.”
“At the minimum call, the copilot stated three whites with reference to the PAPI indicating high above the glidepath,” the report said.
The aircraft was found to be not on the correct flight path and the rate of descent significantly exceeded 1,000 ft per min with the glideslope indicator indicating a rapid deviation from half dot low at the (minimum descent altitude), to two dots high within nine seconds after passing the (minimum descent altitude) in IMC.”
-The investigation found that the crew did not take any remedial action in response to the Glideslope and Sink Rate Caution 64 alerts (aural alerts).
- The investigation found that the crew had received similar aural alerts on previous approaches in visual conditions where the aircraft was safely landed.
- The AIC Human Factors investigation determined that it is likely that a hard aural ‘WARNING’ alert or a flashing visual pull-up would have more effectively drawn the attention of the pilots during this critical phase of flight where workload was higher and attention fixated. It could be the last line of defence for any crew who may unknowingly or inadvertently get in a similar fixated situation.
“The Air Niugini Standard Operating Procedures Manual instructs a non-flying support pilot to take control of the aircraft from the flying pilot and restore a safe flight condition when an unsafe condition continues to be uncorrected, in particular an unstable approach when the aircraft is in (instrument metreological conditions) and below 1,000ft,” the report said.
“However, the copilot as the nonflying support pilot did not do so. The pilot in command did not carry out the required go around at the minimum descent altitude.”
According to the report, however, the pilot was found to be unaware of the developing unsafe conditions, and thus was unable to recognize the need to correct the increasing dangerous rate of descent below the glideslope.
“The crew were not complying with Air Niugini SOPs, and demonstrated that they were not situationally aware, and that their attention was channelized. Their actions indicated that they were fixated on a particular aspect and did not address the alerts and take corrective action,” the report said.
Hubert Namani, chief commissioner of the PNG Accident Investigation Commission, said “inattention, or decreased vigilance” contribute to operational errors, incidents and accidents worldwide.
“Decreased vigilance manifests itself in several ways, which can be referred to as hazardous states of awareness,” Namani said.
In the Air Nuigini case, he added, “Both pilots were fixated on cues associated with control inputs for the landing approach, and subsequently, were not situationally aware and did not recognize the developing significant unsafe condition of an increasingly unstable final approach.”
Namani said the report highlighted the danger of deviating from recommended practice and SOPs, particularly during the approach and landing phase of flight.
During the flight, before the top of descent briefing, the oral communications between the pilot in command, the copilot and air traffic control were in a normal tones and in an orderly manner. However, during the approach below 10,000 feet, communication between the pilots was minimal and not in accordance with SOPs, and they were not using standard phraseology, the report said.
The report also underscored the importance of crew coordination and action as an integrated team.
The accident took place just after Air Nuigini expanded its service in the Federated States of Micronesia with the launch of twice-a-week direct flights between Narita and Chuuk.