A quick-thinking Aer Lingus Regional pilot and co-pilot saved their plane and 46 passengers by flying into a rain shower to clear sea salt which had completely caked their aircraft windscreen.

The revelation came as an Air Accident Investigation Unit (AAIU) report praised "the good airmanship" of the crew of the ATR-72 flight from Manchester to Cork whose skill averted a potential accident at 10.50pm on January 2 2014.

The AAIU described it as "a serious incident."

The build-up of sea salt on the windscreen, caused by stormy conditions during their flight over the Irish Sea, is one of the rarest challenges faced by pilots.

In the case of the seven-year old ATR turbo-prop attempting to land at Cork Airport, the 40-year old female pilot and her co-pilot were shocked to realise a thick layer of white sea salt had caked over their windscreen as they were attempting to land.

The condition of the windscreen was only apparent to the pilots, whose entire flight was conducted in darkness, when they had to abort their first attempted landing at Cork due to a significant increase in indicated airspeed because of the stormy conditions.

"The aircraft then positioned under radar control for a second approach to the same runway," the AAIU report revealed.

"Its track brought it south of (Cork), close to the coast and at times over the sea. During this time, a thick layer of sea salt formed on the front windscreens, obscuring the flight crew’s forward visibility."

Expand Close Contamination on windscreen of Aer Lingus Regional flight. Credit: Air Accident Investigation Unit (AAIU / Facebook

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Whatsapp Contamination on windscreen of Aer Lingus Regional flight. Credit: Air Accident Investigation Unit (AAIU

"As it was not possible to acquire the necessary visual references for landing, a second go-around was flown."

The AAIU report found that such a salt build-up can occur in specific weather conditions.

However, it was particularly severe in the case of the Manchester-Cork flight that evening.

The bulk of the salt is believed to have gathered on the windscreen when the plane had descended to a height of 1,000 metres (3,000 feet).

"The flight crew were faced with a very rare but significant issue when the forward visibility through their windscreens was obscured due to sea salt accretion on the windscreens, while attempting a night landing at (Cork) during a winter storm."

But the quick-thinking pilot and co-pilot immediately flew into an area of heavy shower activity - and used the rain in an attempt to wash clear the windscreen.

The pilot has over 5,000 hours flying experience and, critically, over 4,700 hours have been logged on the ATR-72 type.

"A small portion of the commander’s windscreen was cleared. A third approach was flown to a successful landing," the AAIU report added.

The AAIU investigation was unstinting in its praise of how the Aer Lingus Regional crew reacted.

"Following the second go-around, the flight crew showed good airmanship and crew resource management in seeking to fly to areas of shower activity which were visible on their weather radar."

"They were facilitated in this by Air Traffic Control and they found areas of moisture which, although not active enough to completely clear the windscreen, did clear a small area of the windscreen on the commander’s side."

The pilot commenced her successful final approach to Cork peering through "this small gap (washed) in the salt residue."

"At the time, the first officer still had no visual reference," the AAIU report pointed out.

Two other planes reported similar sea salt build-up on their windscreens that night but none as severe at the Manchester flight.

The AAIU pointed out that it was "noteworthy" that the flights of two of the aircraft involved that night, both French-built ATR-72s, found that the windscreen wipers were ineffective in clearing off the salt.

"The commander of (the Manchester flight) also stated that she believed that the windscreen heat had exacerbated the issue by drying out the salt and enabling a thick layer to form."

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