On 28 September 2018, a Boeing 737-800 (P2-PXE) being operated by Air Niugini on a domestic passenger flight from Pohnpei to Chuuk as PX73 impacted the sea 460 metres prior to the threshold of the intended destination landing runway 04 in day IMC after continuing its approach below MDA. All but one of the 47 occupants exited the aircraft before it sank and were promptly rescued. The body of the passenger who did not exit the aircraft was subsequently recovered from the wreckage. Six of the surviving passengers sustained serious injuries and the remainder of the passengers and all crew members were uninjured. The aircraft was destroyed by impact forces and subsequent submersion in salt water.
An Investigation was commenced by the Division of Civil Aviation of the Department of Transportation, Communications and Infrastructure (DT & CI) of the Federated States of Micronesia (FSM) with considerable assistance from the Papua New Guinea Accident Investigation Commission (AIC) in accordance with the principles of ICAO Annex 13. The aircraft SSCVR and SSFDR were recovered by divers and their data were subsequently successfully downloaded by the Papua New Guinea AIC. Divers also recovered the Automatic Flight Information Recording System (AFIRS) and EGPWS which were sent to their respective manufacturers where recovery of relevant data from the EGPWS was achieved under the supervision of the NTSB and that from the AFIRS unit was achieved under the supervision of the Canadian TSB. The AFIRS data was found to be “consistent with the data from the FDR”. An engineer travelling on the flight (see below) occupied the flight deck supernumerary seat during the approach and for personal interest video-recorded it from about 3000 feet on his smart phone. This survived the accident up to impact and was of high quality, providing “an invaluable source of vital information to complement and enhance the data from the FDR, CVR, AFIRS and EGPWS”.
A Preliminary Report describing the initial findings of the Investigation was issued on 26 October 2018. On 14 February 2019, the FSM Government formally delegated the whole of the Investigation to Papua New Guinea as State of Registration and State of the Operator as permitted by ICAO Annex 13 which obligated the accepting State to complete the Investigation and issue the Final Report.
The final sea bed position of the aircraft relative to the intended landing runway. [Reproduced from the Official Report]
It was noted that the 52 year-old Captain, who had been PF for the accident flight, was of Papua New Guinean nationality and had a total of 19,780 hours flying experience which included 4,987 hours in command of which 2,276 hours was on type. He had no experience on the 737 except this time in command and had gained his specific route and aerodrome familiarity “several months prior to the accident flight” by observing from the supernumerary crew seat. Air Niugini procedures did not require prior hands-on flying experience as a pre-requisite for specific flight operations. The 35 year-old First Officer was of Australian nationality and had a total of 4,610 hours flying experience which included 368 hours on type. It was noted that under the prevailing flight and duty regulations, the off duty rest period prior to beginning the accident flight duty at Pohnpei for all crew members was 10 hours but the actual time off duty had been 8 hours 50 minutes. However, no evidence that fatigue had played any part in the accident was found.
The aircraft departed from Pohnpei for the one hour flight to Chuuk - which was scheduled to then continue to Port Moresby - half an hour late. An engineer employed by the company from whom the aircraft was leased was on board the flight in accordance with their policy that one of their engineers should be on board every flight away from Papua New Guinea to provide ground maintenance support. This engineer was the one present on the flight deck during the approach who had made the video recording of the final 3000 feet of descent up to impact.
It was established that prior to beginning of descent the crew, expecting to use the 1,831 metre long runway 04 for the landing at Chuuk, had briefly discussed the brake setting for the landing and then discussed the approach and landing flap setting. After the Captain had initially stated that “Flaps 30 would do”, the First Officer determined by use of the OPT installed on the Company EFB that Flap 40 would slightly reduce the landing distance and it was agreed to use Flap 40. The crew then discussed the intended RNAV approach procedure (see the illustration below) and associated MAP, however “the approach and landing checklist and the briefing on the RNAV approach chart were not conducted in accordance with the SOPs and or by use of standard phraseology (and reference to) the missed approach was just a cursory mention of DAMAY and did not cover the procedure, nor the flight path to be followed”.
The RNAV approach procedure flown. [Reproduced from the Official Report]
Descent from the FL 400 cruise began after 34 minutes airborne and twelve minutes later, the First Officer called Chuuk Radio to obtain the Chuuk weather and was informed of light and variable surface winds, scattered Cb cloud at 1400 feet and temperature/dew point 26/25°C. Twenty minutes later, with the aircraft passing 8,600 feet and about 15 nm from Chuuk, the First Officer broadcast their intention to make the RNAV (GPS) approach to runway 04 joining from the east south-east. Five minutes later, he followed this with a broadcast that they were established on the 041° inbound track and the Captain called for gear down and flaps 15.
The First Officer remarked that “there were some showers in the area” and the Captain responded with “that must be some storm, but it’ll be out soon” and called for the landing checklist, but the only response from the First Officer was “landing gear, flaps and lights and runway in sight” to which the Captain responded with “ah we’ll probably just go down on the PAPI’s”. Seven seconds later he said “alright flaps 30, flaps 40” and followed this with “landing checks”. At the 1,000 feet auto callout, the First Office stated “OK, stable” which the Captain followed with “continue” and the First Officer then said “and visual, 900 cloud base”.
Passing 625 feet QNH (677 feet agl) with the aircraft above the 3º glideslope, the Captain disconnected the autopilot and said “I’m going back on profile” and two seconds later, the aircraft entered a storm cell and heavy rain and the wipers were switched on. As the MDA was approached, the Captain said “okay, landing”, the First Officer said “visual, one red”, paused and then said “three whites” with the auto callout ‘MINIMUMS’ following immediately. The recorded rate of descent at this point was 1,490 fpm. Seven seconds later, with the recorded rate of descent now 1,530 fpm, the first of a series of EGPWS ‘SINK RATE’ Alerts began and were followed by three EGPWS Mode 5 ‘Glideslope’ Cautions and these then alternated for the rest of the flight. The First Officer questioned whether the Captain could still see the runway and with no response, the ‘100’ auto callout occurred. Further SINK RATE Alerts and Mode 5 Glideslope Cautions followed and five seconds after the “100” auto callout, with the aircraft approaching 30 feet agl, the last of the SINK RATE Alerts occurred and the First Officer called out “rapidly and with high intonation” that the aircraft was “Too low! We’re too low! We’re too low! We’re too low!” with impact following two seconds later.
The main landing gear separated from the wings during impact and the fuselage was ruptured around the circumference of the lower section below the window line behind the wings at seat rows 17 and 22 and was then held in place principally by piping and cables and the intact upper fuselage structure. Water rapidly entered the passenger cabin and the evacuation commenced immediately. Most occupants were able to evacuate the aircraft unaided but the six seriously injured passengers, one of whom was found by cabin crew still strapped into his seat, were helped from the aircraft via the left rear over-wing exit by cabin crew and fellow passengers. It was established that the single passenger fatality and all the serious injuries sustained had involved passengers seated in rows 18-23 towards the rear of the aircraft. The fatally injured passenger had not been wearing his seat belt and was subsequently assessed to have died within three minutes of impact as a result of sustaining “traumatic head injuries” during impact rather than from drowning.
Soon after the evacuation had been completed, the aircraft sank 90 feet to the seabed of the Chuuk Lagoon where it came to rest with the nose of the aircraft oriented towards approximately 265. Photographs subsequently taken showed that it had sustained further major fracturing, including opening up of the initially damaged areas which had extended around the circumference of the fuselage.
A detailed review of the evacuation and associated procedures aimed at facilitating it was carried out and a number of findings were made which it was considered required corrective, although none of these had a direct bearing on the actual evacuation performed. These included but were not limited to the fact that the armed internal and external emergency lighting did not illuminate following impact for reason(s) that could not be determined. It was found that there was no procedure that would require the pilots to activate the emergency lights manually to assist evacuation and considered that it was “essential for the emergency lights to be activated in the event of any occurrence requiring evacuation to assist with visibility in the aircraft”.
The performance of the flight crew
It was evident from the video recording that a storm cell situated immediately after the procedure MAP at ‘HAMAX’, was clearly visible on the weather radar and that the aircraft had continued past the MAP and flown into IMC with initially light and subsequently heavier rain. The CVR and the video recording both showed that the crew did not discuss avoidance actions. During interview, the Captain stated that “he believed he was arresting the descent and also that the aircraft was sluggish” whereas this perception was contrary to the factual evidence. It was also noted that there was “no evidence in the recorded data to suggest that environmental forces, such as downdrafts, updrafts, etc, influenced aircraft movement against pilot control inputs”.
The vertical profile flown with no corrective action to regain the procedure/PAPI 3° glideslope. [Reproduced from the Official Report]
Overall, it was considered that the Captain “had lost situational awareness and that he was fixated on the task of completing the approach and landing the aircraft (and had) continued the approach despite the excessive rate of descent while in IMC and below the MDA”. During his interviews, the First Officer said that he had believed that they had been “pretty much stable on approach all the way down” and that he had been unaware that the aircraft was deviating from the intended flight path and thereby taking it towards the water. He also said that “the showers came out of nowhere (and) caught us by surprise”. It was observed by the Investigation that the First Officer “did not proactively monitor the instruments in response to the EGPWS aural call outs of an unsafe situation throughout the approach”.
The Investigation noted from the downloaded FDR data that the approach to runway 09 at Pohnpei during the outbound Chuuk-Pohnpei flight the previous day by the same flight crew was also made “significantly below the 3-deg flightpath (glideslope) thus prompting the EGPWS to issue a total of 28 “Glideslope” aural alerts" following which no corrective action to return the aircraft to the required flightpath had been taken and, contrary to Air Niugini SOPs, a sterile flight deck had not been maintained.
It was considered that during the accident approach, the Captain had demonstrated a behaviour characterised as ‘task fixation’ in which credible signals that should demand attention are either consciously or unconsciously disregarded. The continuation of the approach when below MDA as the necessary visual reference was lost, the failure once on instruments to respond to aural alerts of an excessive rate of descent and an apparent failure to notice descent below the indicated glideslope to the eventual extent of ‘off scale’ or to notice a visual only ‘PULL UP’ Warning led progressively to an inevitable outcome. The absolute failure of the First Officer to challenge the Captain’s continuation of the approach once visual reference was lost then removed the critical safety net that monitoring is intended to provide.
Air Niugini Risk Assessment and SOPs
A review by the Investigation of the airline’s risk assessments for operations to Chuuk both before the accident and prior to the resumption of operations there after the accident against Annex 13 and 19 Standards found that they “did not meet ICAO Standards for Safety Management Systems and in general were not in accordance with Risk Assessment audit standards and methodology”. In particular it was found that risk assessment documentation showed that “there was little evidence of hazard identification being completed by Air Niugini”. For example, there was no identification of a series of differences from ICAO Standards in respect of Chuuk Airports. These included issues with the Airport Emergency Plan and the fact that there was no RESA at the ends of the runway there. The latter was self-evidently directly relevant to operational risk assessment but was not mentioned in the Air Niugini ‘Route Guide’ for Chuuk.
A further concern was that use of the Boeing-supplied OPT installed on the flight deck EFBs issued to Air Niugini’s 737 pilots had not been authorised by the Papua New Guinea Civil Aviation Safety Authority (PNG CASA) and was not covered by the operator’s FCOM or its Standard Operating Procedures Manual yet the First Officer relied solely on his EFB when establishing landing performance for the accident approach. It was also noted more generally that “a number of obvious safety deficiencies and errors in Air Niugini manuals and Risk Assessment documents” appeared to have been overlooked during their acceptance by PNG CASA.
The absence of any challenge from the First Officer as the final approach situation deteriorated led the Investigation to discover that “Air Niugini manuals tend to use the operating verb “should” instead of the imperative operating verb “shall” with respect to instructions for compliance with vital and essential safety of flight actions”.
It was also found in respect of pilot simulator training that it “did not include training in the vital actions and responses to be taken by the non-flying pilot in the event of a sustained unstabilised approach situation developing when below 1,000 feet amsl and when in IMC”.
The formally documented Findings of the Investigation included, but were not limited to, the following:
- The flight was not conducted in accordance with the procedures in the Air Niugini Standard Operational Procedures Manual.
- The pilots did not ensure they had the required flight documents prior to departure from Port Moresby. They only had one RNAV (GPS) RWY 04 chart for Chuuk.
- The pilots’ actions and statements indicated that they had lost situational awareness from 625 ft on the approach and their attention had become channelised and fixated on completing the approach and landing the aircraft.
- Prior to entering the area of heavy rain, the First Officer called “three whites” showing on the Chuuk runway 04 PAPI at the MDA indicating that the aircraft was slightly high on the glideslope. The aircraft vertical profile to impact was an average of 4.5° and was flown in excess of 1,000 fpm in IMC.
- The continuation of the approach at an excessively high rate of descent, in IMC and below the MDA resulted in the aircraft continuing descent below the glideslope and impacting the water 1,500 ft (460 metres) short of the runway 04 threshold.
- The pilots did not respond to the 16 EGPWS aural caution alerts, and the PULL UP visual warning displayed at the bottom of the Primary Flight Display (PFD).
- The Captain did not change his plan to land the aircraft even though the aircraft was in an unstabilised condition in IMC.
- Both pilots ignored the alerts and warnings and were unaware of the unsafe situation developing.
- The Air Niugini simulator training and checking policies and procedures did not require training and testing in the practical application of the challenge and response requirement for the monitoring pilot to take control of the aircraft if a challenge to an unsafe situation, including EGPWS aural alerts went unresolved.
- There was no requirement or procedure in any Air Niugini manual or the Quick Reference Handbook (QRH) Evacuation Checklist to instruct or guide the pilots and cabin crew in the operation of the emergency lights.
- Despite the fact that Chuuk airport is surrounded by water on three sides, implementation of the Airport Emergency Plan with respect to water emergency rescue had not been practised and the Plan itself did not meet ICAO Annex 14 Standards.
- In the absence of a RESA, the Chuuk airport runways did not meet ICAO Annex 14 Standards.
- The Federated States of Micronesia, as a contracting ICAO State, had not notified differences from applicable ICAO Annex 14 Standards or notified them in the AIP.
- The Papua New Guinea Civil Aviation Authority did not meet the high standard of evidence-based assessment required for safety assurance, resulting in numerous deficiencies and errors in the Air Niugini Operational, Technical, and Safety manuals.
The Causes (Contributing Factors) of the accident were documented as follows:
- The flight crew did not comply with the 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 autopilot disconnect at 625 feet (677 feet QNH). From 546 feet (600 feet QNH) the aircraft was flown in IMC and the rate of descent significantly exceeded 1,000 fpm in IMC from 420 feet (477 feet QNH).
- 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 Captain did not execute the missed approach at the MAP despite:
- the 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
- the EGPWS visual PULL UP warning on the PFD.
- The monitoring performance of the First Officer was ineffective and he was oblivious to the rapidly unfolding unsafe situation.
It was considered by the Investigation that had a continuous ‘WHOOP WHOOP PULL UP’ hard EGPWS aural warning been annunciated simultaneously with the visual display of PULL UP on the PFD (and ideally with a flashing visual display of PULL UP on the PFD), it could have been effective in alerting the crew of the imminent danger and prompted a pull up and execution of a missed approach that may have prevented the accident. It was noted that the absence of an aural ‘PULL UP’ Warning on the aircraft involved (a 2005 built example of the type) was suggested by both Honeywell and Boeing as possibly because such a capability “might not be an option for older generation EGPWS”.
Safety Actions taken by Air Niugini on its own initiative as a result of the accident and notified to the Investigation team included the following:
- On 23 October 2018, it advised that it had replaced the Boeing 737 on services to Chuuk and Pohnpei with Fokker28 aircraft and that Chuuk and Pohnpei airports had been re-categorised from CAT B to CAT X (CAT X being more restrictive).
- On 11 April 2019, it further advised that the following flight operations and training changes had been introduced:
- Chuuk can only be nominated as a destination airport for arrival during daylight hours
- Tailwind component for landing in Chuuk reviewed and amendments made in the Air Niugini Boeing Route Guide Section 6
- Fuel tankering policy had been reviewed and amendments made to the Air Niugini Boeing Route Guide
- Destination holding fuel requirements for airports with weather issues had been reviewed
- Aircraft with any open braking aid MELs shall not be operated into Chuuk
- More approach and landing exercises with a sudden loss of visibility and with approaches using flap 40 to a limiting runway had been added to the recurrent simulator training cycle
- The go-around policy as per Air Niugini SOP section 12.5 had been reviewed and amended
- Procedures to define categories of airports and the corresponding additional training requirements had been introduced
- The expiry of crew airport-specific qualifications now triggers an alert in the Air Niugini crew rostering system.
A total of 17 Safety Recommendations were made during the Investigation. All addressed safety deficiencies identified but only in the case of two recommendations, distinguished in bold below was it considered that these deficiencies “may have been a contributing factor in the accident”. Recommendations are listed in date of issue order and this date is shown immediately after the recommendation number at the end of each one:
- that Air Niugini should ensure that the Safety on Board Card (passenger briefing card) for the Boeing 737-700 and -800 fleet accurately shows the exits to be used in a water ditching accident and the accurate depiction of which exits have life rafts deployed. [18-R04/18-1004 - 24 November 2018]
- that Air Niugini should, as a matter of urgency ensure that:
- all crew members are reminded of their obligation to comply with PNG Civil Aviation Rules, the Air Niugini Special Emergency Procedures (SEP), and the Air Niugini Corporate Emergency Response Manual, in particular Section 6.9.3;
- all crew members are reminded of their obligation to ensure that passengers do not take any baggage from the aircraft (in an emergency evacuation). [19-R03/18-1004 - 4 February 2019]
- that Air Niugini should review its policy and procedures in the Safety and Emergency Procedures Manual (SEPM) in relation to all aircraft in the Air Niugini fleet to ensure that:
- a responsible and capable adult passenger is seated in the over wing exit row on all flights.
- the passenger(s) seated in the over wing exit row are fully briefed on the tasks required to deploy the emergency exit and assist in passenger evacuation. [19-R04/18-1004 - 4 February 2019]
- that Air Niugini should ensure that in order to mitigate the risk of a cabin crew member being unable to reach the over wing exit due to passenger congestion, it reviews the policy and procedures in the Safety and Emergency Procedures Manual (SEPM) and the Airport Services manual (ASM) in relation to all aircraft in the Air Niugini fleet to ensure a cabin crew member is seated in the over wing exit row on all flights. [19-R05/18-1004 - 4 February 2019]
- that Air Niugini should ensure that cabin crew are fully conversant with the requirements of the Safety and Emergency Procedures Manual (SEPM), Volume 6, Section 184.108.40.206 with respect to the evacuation procedures when no life raft is deployed from the forward exit doors. [19-R06/18-1004 - 4 February 2019]
- that Air Niugini should review the Safety and Emergency Procedures Manual - Volume 6 (B737) Section 3.2.2 titled P2-PXC / P2-PXE - location of Emergency Equipment to ensure the diagram clearly depicts the correct life raft stowage locations, and ensure all cabin crew are briefed on the correct location of the life rafts. [19-R07/18-1004 – 6 February 2019]
- that Air Niugini should ensure that all flight crew comply with the Air Niugini Limited Standard Operating Procedures Manual (SOPM) and the Flight Crew Operating Manual (FCOM) with respect to operational procedures and primary flight crew duties, and do not use personal Electronic Flight Bag (EFB), and specifically do not use the Boeing OPT data during flight operations until approved by Air Niugini Limited. [19-R01/18-1004 - 7 February 2019]
- that the Federated States of Micronesia Division of Civil Aviation, (representing) a contracting State to the Convention on International Civil Aviation should ensure that:
- Chuuk International Airport meets ICAO Annex 14 Standards with respect to Airport Emergency Planning and specialist rescue services (equipment and personnel) for an emergency situation that might occur outside the airport perimeter in water or
- if the State is unable to comply with the Standards of Annex 14 as identified in (a) above, it will file with ICAO the difference between the State’s national regulations and practices and the related ICAO Annex 14 Standards and Recommended Practices and publish the filed difference(s) through the Aeronautical Information Service. [19-R08/18-1004 - 8 February 2019]
- that Air Niugini should ensure that all flight crew are tested for competency in the vital actions and responses to be taken in the event of a GPWS or EGPWS warnings, and/or an unstabilised approach situation developing when below 1,000 feet amsl and in instrument meteorological conditions. [19-R09/18-1004 - 17 February 2019]
- that Air Niugini should ensure that:
- Section 220.127.116.11 of the Standards Operating Procedures Manual is amended to use the operating verb “shall” for the instructions for compliance with the vital and essential safety of flight actions.
- All Air Niugini Limited Operational and Training manuals are reviewed and revised as necessary and (amended) to use the operating verb “shall” when appropriate to ensure the importance of taking essential safety action is recognised. [19-R10/18-1004 - 18 February 2019]
- that Air Niugini should, as a matter of urgency, ensure that the relevant Air Niugini manuals, including the Quick Reference Handbook Evacuation Checklist, are amended to provide instructions and emergency procedures for the manual operation of the emergency lighting switch in the cockpit, and the switch located on the Aft Attendant’s Panel, and that all pilots and Cabin Crew are instructed in their importance and use. [19-R11/18-1004 - 20 February 2019]
- that Air Niugini should, as a matter of urgency, ensure that the Training Reference Manual and all relevant Air Niugini manuals related to emergency evacuation are amended to ensure descriptors on drawings are clear and unmistakeable, and that the Training Reference Manual and operational procedures clearly stress the requirement for life rafts to be deployed outside the aircraft before attempting inflation. [19-R12/18-1004 - 25 February 2019]
- that the Civil Aviation Safety Authority of PNG should draft Civil Aviation Rule(s) to require the fitment of image recorders in the cockpit of all CAR Part 125 and 135 aircraft, and promulgate through the April 2019 Notice of Proposed Rule Making (NORM) process. [19-R13/18-1004 - 8 April 2019]
- that Air Niugini should review the Air Niugini Risk Assessment process and methodology to ensure they meet ICAO Annex 19 Standards and where risk assessments have been made by Air Niugini Limited with respect to aircraft operations that those risk assessments are reviewed to ensure they meet ICAO Standards. [19-R14/18-1004 - 10 April 2019]
- that the Federal Aviation Administration should re-evaluate TSO’s 151b and 151d and DO-367 related to EGPWS warnings and cautions, and ensure that the Honeywell EGPWS MK V Computer provides a timely warning in the form of a continuous flashing visual display of ‘PULL UP’ at the bottom of the Primary Flight Displays, as an absolute minimum standard. A flashing visual display ‘PULL UP’ warning, accompanying an aural ‘SINK RATE’, would require immediate action from the flight crew when encountering an excessive Rate of Descent at very low Radio Altitude, similar to that flown by the crew of P2-PXE. [19-R17/18-1004 - 20 May 2019]
- that Honeywell Aerospace should, in consultation with the Federal Aviation Administration, re-evaluate TSO’s 151b and 151d and DO-367 related to EGPWS warnings and cautions, and ensure that the Honeywell EGPWS MK V Computer provides a timely warning in the form of a continuous flashing visual display of ‘PULL UP’ at the bottom of the Primary Flight Displays, as an absolute minimum standard. The flashing visual display ‘PULL UP’ warning, simultaneously with the aural caution ‘SINK RATE’, would require immediate action from the flight crew when encountering an excessive Rate of Descent at very low Radio Altitude, similar to that flown by the crew of the accident aircraft. [19-R02/18-1004 - re-issued with amended wording 20 May 2019]
- that Jeppesen should ensure that standard terminology is used on both the Chuuk RNAV (GPS) RWY 04 and the Pohnpei RNAV (GPS) X RWY 09 instrument approach charts and should also ensure that terminologies and the layout used on all Jeppesen Instrument approach charts are consistent and standardised. [19-R18/18-1004 - 5 June 2019]
Where received by the time the Investigation was completed, the addressees’ responses and the assessment of the Commission as to the consequences of these responses for the assignment of status by the Commission are included in the Final Report.
The Final Report of the Investigation was completed on 15 July 2019 and subsequently published online.