HT2 - Report: Airwork B734 at Sydney and Auckland on Jun 7th 2022

An Airwork Boeing 737-400 freighter, registration ZK-TLL performing flight HT-2 from Sydney,NS (Australia) to Auckland (New Zealand) with 2 crew, completed a seemingly uneventful flight with a safe landing in Auckland, when during taxiing to the apron the crew discovered, they they still had a full centre fuel tank while the two main fuel tanks supplying the engines had only minimum fuel left. The crew thus noticed that the two center fuel pumps had remained off for the duration of the flight.

New Zealand's TAIC released their final report concluding the probable causes of the incident were:

- The flight crew omitted to turn on the center fuel pumps before starting the aircraft and did not detect that the fuel in the center tank had not been used until after landing in Auckland when a main fuel pump low pressure light illuminated.

- The requirement to reprogramme and replan their departure due to a runway change and the approaching curfew added to the pressure the flight crew were under and very likely contributed to distraction when they were completing the Before start checklist.

- If the aircraft had flown a go-around from the approach into Auckland, it is likely that the fuel in the main tanks would have been exhausted during the manoeuvre.

- The operator’s Operations Control Centre (OCC) staff did not provide updated weather forecasts or flight plans to the crew prior to Extended Diversion Time Operation (EDTO) sectors as required by the operator’s OCC Manual.

- The operator’s flights AWK2 and AWK82 departed for Auckland with flight plans nominating destination and EDTO alternates that were not compliant with regulatory or company flight planning requirements.

- The regulator’s audit identified deficiencies in the operator’s safety management system, both before and after the occurrence. The regulator is monitoring the implementation of the corrective actions taken by the operator to progressively address these deficiencies.

The TAIC analyed amongst many more:

At the time AWK2 commenced the approach, the visibility was still fluctuating but above the required minimum, and as a precaution the crew briefed for and conducted an autoland.

If AWK2 had subsequently flown a go-around from this approach due to the low visibility, fuel consumption would have increased rapidly because of the engines’ high power demands. The fuel on shutdown was noted in paragraph 2.12 as 4640 kg, and with 4000 kg reported in the center tank that left 640 kg in the main tanks. The operator advised that the guidelines for B737 stated that 640 kg would be used for a go-around and further approach. Consequently, it is very likely that during a go-around manoeuvre the master caution light and fuel low pressure light would have activated as fuel in the main tanks neared exhaustion.

In this scenario there was no checklist or procedure that would have directed the flight crew to turn on the center pumps, as checklist logic46 would have assumed that the center fuel had already been used. It would have required the flight crew to analyse the situation and determine that fuel was available in the center tank, which would have been challenging given the high workload of flying a go-around and possible diversion. Therefore, there would have been a very real potential for an engine failure if a go-around had been required. The captain had recognised this and commented that “the risk that we put ourselves in by not turning those pumps on was that had we have had to do a go-round we’ve put ourselves in a situation that may have been critical”.