A pilot and her crew have been praised for their airmanship after they landed safely during a storm despite the windscreen being completely blocked by sea salt.
The Air Accident Investigation Unit (AAIU) said that, given the rarity of the event at Cork Airport last year, there was no need for a safety recommendation.
However, it has advised pilots facing a similar situation that they may have to fly through rain clouds to clear their windscreens before conducting a landing.
The AAIU published its report yesterday into the incident involving a scheduled Aer Arann flight from Manchester to Cork on January 2, 2014.
There were 46 passengers and four crew on board the ATR-72 aircraft as it came in to land just before 11pm.
Weather conditions were stormy around the airport, with winds gusting up to 50 knots.
There were warnings of severe turbulence and windshear in force.
There were no issues with forward visibility from the cockpit during the first approach to runway 25 but an increase in wind speed forced the pilot to abandon the landing attempt and execute a go-around.
She flew the aircraft in a southwesterly direction, then turned on to an easterly track to the south of the airport to make a second final approach to the same runway.
This track to the south brought the aircraft close to the coast and at times over the sea at an altitude of 900m.
However, as the pilot made her second approach, a thick layer of sea salt built up on the cockpit windscreen, blocking her view of the airport and runway completely, and forcing her to execute a second go-around.
The windscreen wipers did not clear the sea salt and the windscreen heating system made the problem worse by drying the salt into a thick layer on the glass.
“The problem I have is that I can’t see out the windscreen,” she told air traffic controllers.
The pilot considered diverting to Shannon but identified an approaching rain shower on the aircraft’s weather radar and was cleared by air traffic controllers to fly the aircraft towards it in an effort to clear the sea salt residue.
This manoeuvre cleared a tiny portion of her side of the windscreen — about 7.5cm wide and 2.5cm high towards the bottom of the windscreen. The first officer had no visual reference at all.
However the AAIU report said the clearing was enough to allow the pilot see the runway and make a third approach, during which a rain shower crossed over the airport, further clearing the windscreen.
The pilot managed to land the aircraft successfully and safely just before midnight.
Three inbound flights were affected by the same sea salt residue that night but the Manchester flight was the worst affected.
The AAIU said the sea salt accretion was most likely caused by a confluence of meteorological circumstances including high marine surface winds combined with a lack of precipitation.
The unit has also reminded airlines that, in the event of an aircraft operating in areas of high concentrations of sea salt aerosol, particular attention should be paid to the washing of engines and airframe as a corrosion prevention measure.
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