Vanuatu AT72 at Port Vila on Jul 28th 2018, engine failure and smoke, runway excursion, collision with 2 other aircraft
Last Update: October 29, 2019 / 15:15:00 GMT/Zulu time
Incident Facts
Date of incident
Jul 28, 2018
Classification
Accident
Cause
Runway excursion
Aircraft Registration
YJ-AV71
Aircraft Type
ATR ATR-72-200
ICAO Type Designator
AT72
The engine malfunction, although not directly causal to the accident, caused the generation of smoke, which prompted the declaration of a ‘Mayday’ and an immediate descent.
The smoke detection by the electrical smoke detector caused the ambiguous ‘ELEC SMK’ warning to activate in the cockpit causing the PIC’s confirmation bias and subsequent diversion of the attention away from the engine issue.
The confirmation bias created by the ambiguous ‘ELEC SMK’ warning led to the selection and action of the ‘Electrical Smoke’ checklist
The copilot’s lack of aircraft systems knowledge and introverted behaviour increased the workload on the PIC and contributed to the steep cockpit authority gradient. This significantly contributed to the degraded CRM.
The oversight of the ‘Note’ in the QRH ‘SMOKE’ checklist and the absence of similar information in the QRH ‘ELECTRICAL SMOKE’ checklist encouraged the crew to continue the checklist without other consideration.
The ACW generators were switched off and the DC BTC was isolated through compliance with the QRH ‘ELECTRICAL SMOKE’ checklist by the flight crew resulting in the loss of hydraulic system pump power and the illumination of several fault lights.
The crew were referred by the QRH ‘ELECTRICAL SMOKE’ checklist action of the QRH ‘ACW GEN 1+2 LOSS’ checklist and completed the ‘before landing’ section in place of the normal QRH ‘Before Landing’ checklist. This caused the crew not to check the TLU setting.
With the DC BTC isolated, the shutdown of the No. 2 engine caused all DC bus 2 supplied systems to lose power. This resulted in a number of system faults, failures and cautions.
The activation of numerous fault and failure messages as a result of the QRH ‘ELECTRICAL SMOKE’ checklist and the shutdown of the No. 2 engine, significantly contributed to crew cognitive saturation and reduced situational awareness and crew vigilance.
The lack of situational awareness caused the crew to select reverse thrust with ground control and braking systems unavailable.
The selection of reverse thrust caused the aircraft to turn to the left and exit the runway.
The absence of hydraulic control, brakes, and aerodynamic control prevented the crew from correcting the undesired course change, runway excursion, and subsequent collision with the parked aircraft.
The AIC analysed with respect to the flight crew:
The PIC was qualified and had significant experience in command of ATR 72-500 aircraft. His recurrent simulator training records showed that smoke control and removal techniques had not been tested since May 2015. It is likely that along with the ambiguous warning, in a time critical situation, the lack of recent experience on smoke control and removal training contributed to the confirmation bias and uncertainty that he experienced during the accident flight.
The copilot had an ATR 72-500 type rating. However, he was inexperienced and had minimal hours on ATR type aircraft. He was undergoing line training at the time of the accident. His on-going training records also showed evidence of inadequate systems knowledge and this was apparent during the accident flight. This contributed to his degraded level of assertiveness and affected his ability to be an effective flight crew member. This was also an area of deficiency that he was advised to address during training flights prior to the accident.
The investigation determined that the flight crew did not have adequate systems knowledge, particularly with regard to a smoke emergency. This contributed to the mis-diagnosis of the smoke source, and the subsequent selection and actioning of the incorrect checklist.
With respect to the execution of checklists the AIC analysed:
The crew started the QRH ‘ABNORMAL ENG PARAMETERS IN FLIGHT’ checklist (see Appendix B, 5.2.2), when they received the No. 2 engine ITT gauge caution, which would have likely led them to shut down No. 2 engine. However, continued interruptions from the PIC communicating with the cabin crew and Vila ATC created a distraction that prevented them from completing the checklist.
As the PIC ended a radio transmission to Vila ATC, the ‘ELEC SMK’ warning activated. The crew did not return to the QRH ‘ABNORMAL ENG PARAMETERS IN FLIGHT’ checklist. However, they referred to and actioned the QRH ‘ELECTRICAL SMOKE’ checklist.
The investigation determined that the smoke originated from the No. 2 engine. If the crew had completed the QRH ‘ABNORMAL ENG PARAMETERS IN FLIGHT’ checklist and shut down the No. 2 engine, the smoke source would have been isolated. The investigation also determined that, even after abandoning the QRH ABNORMAL ENG PARAMETERS IN FLIGHT’ checklist, had the crew correctly diagnosed the smoke source and completed the appropriate smoke checklist, ‘AIR COND SMOKE, E26.03’ checklist (see Appendix B, 5.2.4), the No. 2 engine would have eventually been shut down isolating the smoke source.
The flight crew used the ATR QRH for respective emergency procedures throughout the emergency. They did not action checklists in accordance with Air Vanuatu SOP, which states:
‘If a checklist is interrupted, reading must be resumed one step before the last read item’.
Normal checklists were not completed during the emergency phase of flight.
It was evident that aspects such as cognitive saturation, lack of situational awareness, time pressures, inadequate systems knowledge, checklist ambiguity, and confirmation bias influenced the crew’s decision making, which led to incorrect checklist selection, prioritisation and action.
One such instance was the QRH ‘Before Landing’ checklist, (see Appendix B, 5.2.13). The crew actioned the before landing section of the QRH ‘ACW GEN 1+2 LOSS’ checklist (see Appendix B, 5.2.5), in place of the normal QRH ‘Before Landing’ checklist. This resulted in the crew not recognising that the rudder Travel Limitation Unit (TLU) was locked in the HI-SPD mode. Had they completed the normal QRH ‘Before landing’ checklist, they would have been directed to check the TLU setting and ensured that it was selected manually to the LO-SPD mode and full rudder authority would have been available.
However, the shutdown of the ACW generators through incorrect checklist selection caused the unavailability of the hydraulic system. The Air Vanuatu SOP permits reverse thrust to be used by flight crew as required during single-engine operations. However, the investigation determined that the use of reverse thrust under the prevailing circumstances was inappropriate.
The AIC analysed that during previous flights there had been oil pressure loss events to the right hand engine and stated: "The investigation could not determine whether the previous low oil pressure events contributed in any way to the seizure of the No. 3 bearing." As result of the seizure of the #3 bearing the AIC wrote: "Smoke was liberated from the fractured diffuser case around the No. 3 bearing. The fractures were likely the result of excessive vibration of the bearing when it started to skid and rub against the inner and outer ring following the engine surges."
The AIC continued:
The aircraft’s No. 2 engine failed, which deteriorated the thrust performance significantly. However, when one engine fails, the aircraft is designed to be flown and landed safely on one engine.
The operational engine, No.1 (left) engine, was brought into flight idle as the copilot retarded the power levers during the flare. As soon as one of the landing gear absorbers was compressed, the weight-onwheels switch allowed the power levers to be brought back past the ground idle detent to the maximum reverse position.
Full rudder authority was not available for the approach and landing due to the high-speed lockout of the TLU during engine shutdown. The crew only had +/- 4° rudder deflection available on either side of centre. Without the full 27° available, the aircraft’s aerodynamic lateral control was significantly limited.
The hydraulic system was not available during the approach and landing. This resulted in the loss of the main braking system, and nose-wheel steering.
The hydraulic accumulator allows six braking applications for emergency brake usage. However, recorded data analysis and PIC statements confirm that emergency brakes were not applied.
With respect to human factors the AIC stated:
The investigation determined through the CVR data analysis of the day’s flights, that the Crew Authority Gradient was generally steep. This is naturally the case when the Captain is a highly experienced, well respected pilot and holds a position of high regard. The PIC was the ATR Fleet Manager. The copilot was new to the aircraft and was still undergoing line training at the time of the accident. CVR data analysis led to the determination that the copilot was very reserved and lacked assertiveness throughout the flight, and even more so during the emergency phase. He did not raise any concerns or question any actions throughout the flight.
...
The lack of appropriate crew resource management (CRM) was evident and the investigation found that some of the contributing factors were the difference in crew experience levels and inadequacies in the copilot’s ATR systems knowledge. The crew’s technique for the application of the QRH checklists was unorthodox, rushed, and not in accordance with the established standard operational requirements.
With respect to the operator's performance the AIC analysed:
The investigation found that the Operator did not comply with the CAAV approved Air Vanuatu Check and Training Manual with regard to training and recurrency. The PIC’s training records showed that he had not done smoke training since 11 May 2015. The training requirements under the Air Vanuatu Training Manual did not provide adequate guidance and emphasis on smoke emergencies.
There were many other training areas that were reviewed and found non-compliant with the Air Vanuatu Operations Manual approved and certified by CAAV to be compliant with the New Zealand CAA adopted Civil Aviation Rules (CAR’s). The lack of appropriate and regulated training was a contributed to the PIC’s decision-making.
The investigation determined that cabin crew training was inadequate. The actions and inactions of the cabin crew during the emergency phase of the flight were not adherent to the ATR CCOM and CCTM adopted by Air Vanuatu Limited. This was seen as a matter of concern as the smoke event lasted about almost 20 minutes and the cabin crew did not don their PBE’s and provide wet towels to the passengers to help ease the inhalation of smoke. the appropriate care to the passengers was not given.
Furthermore, the investigation found that the passengers and crew were not medically tested for carbon monoxide poisoning after the accident.
Incident Facts
Date of incident
Jul 28, 2018
Classification
Accident
Cause
Runway excursion
Aircraft Registration
YJ-AV71
Aircraft Type
ATR ATR-72-200
ICAO Type Designator
AT72
This article is published under license from Avherald.com. © of text by Avherald.com.
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