“Human error caused aircraft accident in Tanzania” - Report

By Osoro Nyawangah, MWANZA Tanzania

Failure for flight crew to follow and correct the plane Enhanced Ground Proximity warnings and the decision to land amid poor weather conditions at Bukoba airport are said to be the major cause of Tanzania’s Precision Air plane accident in Lake Victoria last November.

On 6 November 2022 at 0310 hours (0610 hours Local Time) an ATR 42-500 aircraft with registration 5H-PWF and flight number PW 494 took-off from Julius Nyerere International Airport, Dar es Salaam for a scheduled commercial passenger flight to Bukoba.

According to The Air Accident Investigation Branch (AAIB) report posted on the Ministry of Works and Transport website, the Pilot in Command (PIC) who was flying the plane pushed the control column into a nose down position at a rate of 1,500 feet per minute plunging the plane into the lake.

The aircraft broke up on impact with the water but there was no fire.

Of the 43 persons on board, 24 survived without serious injuries but 19 lost their lives including the two pilots and the aircraft was destroyed beyond repair by the impact with water.

“The ATR 42 - 500 aircraft with registration 5H-PWF was on the Visual Flight Rules (VFR) final approach to runway 31 of Bukoba airport in marginal weather conditions when the Enhanced Ground Proximity warning SINK RATE, about the excessively high descent rate came on three times.” The report reads, adding that the warning was not followed by corrective action of the flight crew.

It further states: “Instead, the flight crew pushed the control column into a nose down position. The aircraft continued to descend fast until the ground proximity SINK RATE PULL- UP warning sounded and this time the aircraft was descending at a rate of 1,500 feet per minute. The aircraft crashed in water and THE PULL-UP action coincided with the noise of the aircraft striking the lake surface.”

Much of the flight to Bukoba was uneventful, cruising at Flight Level (FL) 200. The flight reached top of descent at 0458 hours (0758 hours Local Time) when the crew initiated descent to FL 160. 

At 0504 hours (0804 hours Local Time) there was a public address announcement of expected landing at Bukoba at 0526 hours (0826 hours Local Time). Nine minutes later Mwanza Approach advised the flight crew that the weather at Bukoba was fairly good with “wind calm”, “visibility better than 10 km” “partly cloudy” SCT 011, FEW013 CB, BROKEN 080, T21/17 and QNH 1018. 

However, as the flight progressed the crew started to experience signs of poor weather conditions. In their discussion they pointed out that they may have to approach the airport from the mountains (i.e. runway 13) if Bukoba remained below the clouds.

Before landing checklist was performed at 0526:59 hours. Subsequent to this, the auto pilot was disengaged, the flaps were retracted to zero degrees and the landing gear was retracted. Evidently, the crew decided not to land and instead climbed to 5500 ft.

At 0534:43 hours there was an Enhanced Ground Proximity Warning System (EGPWS) warning “TERRAIN, TERRAIN PULLUP”, however the warning was not followed by corrective action of the crew. The crew continued to discuss about the weather and were informed by Bukoba load “control2” (Precision Air handling agent) that weather information had been transmitted to Mwanza Approach.

The advice from Mwanza approach was to wait for 20 minutes before landing as visibility was not good.

The report went on to reveal that at 0543:28 hours there was an EGPWS warning SINK RATE and one second later, there was a pilot control column effort above 10 daN in nose down direction (four points recorded).

“Five seconds later there was another SINK RATE warning and the rate of descent increased to 1,700 ft/min. At 0543:35 hours the F/O called: ’’Lift up Captain’’. One second later, there was a SINK RATE PULL UP warning from the EGPWS.” The report says adding that the rate of descent decreased to 1,500 ft/min. There was no response from the PIC. At 0543:38 the F/O shouted: “Pull up captain” and the aircraft impacted the water.

The report whose purpose is to provide details of initial facts, discussions and findings surrounding the occurrence says that the Pilot In Command was aged 64, held an Airline Transport Pilot’s (ATP) license with type rating for ATR 42/72 airplanes issued on 04th August 2010.

“He had a valid medical certificate class I until 04th January 2023. At the time of the accident, the captain had accumulated about 23,515 hours of total flying time, of which 11,919 hours were as pilot-in-command (PIC) on the type.”

It also revealed that the F/O was 46 years old, held Commercial Pilot Licence (CPL) with type rating for ATR 42/72 airplanes issued on 01st November 2018 with a valid medical certificate class I until 23rd April 2023.

At the time of the accident, the co-pilot had accumulated 2,109 hours of total flying time, of which 1,700 hours were on the type. - Africa