Confusion between the pilots of an ATR 72-500 over a go-around led the aircraft to fly at low level over the Guernsey airport in fog, after its crew breached an approach ban.
The Lithuanian-registered Jump Air aircraft – operating for Guernsey’s Aurigny – had been attempting to land on runway 27, following a service from Southampton on 12 August last year.
Although the captain had believed the weather would improve en route, the runway visual range rarely met the 550m threshold for a Category I approach.
If the runway visual range criteria was not met, an approach ban was enforced which prohibited the aircraft from descending below 1,000ft.
This approach ban was intended reduce the number of missed approaches conducted at minima, and lower the risk of aircraft being manoeuvred at low level in poor visibility.
After being forced to enter several holding patterns, while awaiting better conditions, the crew took the opportunity to commence an ILS approach when the runway visual range lifted to 550m.
But this lift was temporary, and the visibility again deteriorated. The runway visual range did not exceed 450m during the final approach, says the UK Air Accidents Investigation Branch.
When the aircraft descended through 1,750ft on its final approach, the visual range had fallen to 325m, and was still at this level at 1,540ft.
“Both crew members were aware of the approach ban but it was neither mentioned nor included in the approach brief,” says the inquiry, adding that the captain may have reverted to a prior understanding that regulations permitted continuing to minimums.
The first officer “did not challenge” this understanding, it says.
Despite the runway visual range being insufficient for the Cat I ILS, the ATR crew continued to descend below 1,000ft, breaching the approach ban.
Upon reaching the decision altitude of 536ft, about 0.5nm from the runway, both pilots gained visual references to land.
“But there was some confusion between the crew in communicating this,” says the inquiry, which led to the first officer’s calling for a go-around.
Although the captain initiated the go-around, calling for flap retraction and advancing the throttle levers to full power at 70ft above ground, the aircraft remained level and did not climb.
Over the next 15s the aircraft flew over the airport at 61-78ft, deviating to the right of the runway and coming within 40m laterally – and 27ft vertically – of a DME transmitter.
After travelling for about 750m, the aircraft started to climb. The crew diverted back to Southampton where it landed without further incident. None of the 57 occupants was injured.
Cockpit-voice recorder information was overwritten, and investigators had to rely partly on crew testimony to explain why the aircraft’s go-around climb was delayed.
The inquiry says “ineffective communication” meant neither pilot was certain of the other’s intentions just before the go-around – the captain was “surprised” by the first officer’s go-around call.
As he started the go-around, the captain recalled asking for the landing-gear to be retracted, to which the first officer did not respond because the aircraft had not established positive climb.
The inquiry says the flight director would have indicated a 7.1° nose-up pitch once the go-around button was pressed.
It states that the first officer did not initially make any attempt to take control, but prompted the captain to climb, without response.
Eventually the first officer pulled on the control column himself in order to establish a climb and the captain retracted the landing gear.
“Lack of a shared mental model between the pilots had the result that neither was aware of how close to the ground and obstacles they were for an extended period of time,” the inquiry adds.
