An Aer Lingus Regional pilot and co-pilot averted a potential accident by flying into a rain shower to wash away sea salt which had completely caked the aircraft windscreen, an Air Accident Investigation (AAIU) report has revealed.
The crew’s quick-thinking saved the plane and its 46 passengers after story conditions during the flight over the Irish Sea caused a build-up of sea salt on the windscreen, the Irish Independent reports.
The AAIU report described it as “a serious incident” and praised “the good airmanship” of the crew of the ATR-72 flight from Manchester to Cork at 10.50pm on January 2, 2014.
The 40-year-old female pilot and her co-pilot had to abort their first attempted landing at Cork Airport due to a significant increase in indicated airspeed because of the storm 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."
The condition of the windscreen was only apparent to the pilots, whose entire flight was conducted in darkness.
According to the report, while salt can build-up during specific weather conditions, it was particularly severe in the case of the flight that evening.
It is believed the bulk of the salt gathered on the windscreen when the plane descended to a height of 1,000 meters (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."
The pilot and co-pilot flew into an area of heavy shower activity in an attempt to wash the sea salt from the windscreen.
"A small portion of the commander’s windscreen was cleared. A third approach was flown to a successful landing," the AAIU report added.
"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," said the report.
Although two other planes also reported sea salt build-up on their windscreens that night, the accumulation was not as severe as the Manchester flight.
The AAIU stated 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 Irish Independent reports.
"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."