Unlike cars, planes do not have the ability to slow down because of reduced visibility and even the Fairchild Metroliner would have had to land at around 160kph
IT WAS an ordinary foggy day at Cork Airport.
But, shortly before 9am, the fog suddenly seemed to thicken.
One Aer Arann plane landed -- and another Aer Arann plane was scheduled to land once the Manx2 flight from Belfast had made it to the apron.
Passengers gathered in the terminal awaiting a series of scheduled departures to London and European cities, most involving jet aircraft.
But the Manx2 turboprop made first one, and then a second, aborted landing attempt.
It was in a circling pattern over Cork Airport for between 20 and 30 minutes before it made its third and fateful final landing attempt.
A key element of the six investigations now under way into the worst airport crash in Irish civil aviation history will be why the plane didn't divert -- and what communications took place between the Manx2 crew and the control tower.
The investigations will be hampered by the fact that the entire flight crew -- an English and Spanish national -- both died in the tragedy.
Cork Airport officials last night refused to comment on the fog that shrouded the airport amid concerns such comments might affect the ongoing crash investigation.
Similarly, the airport declined to comment on suggestions that visibility had dropped at 9am to somewhere between 350 and 400 metres.
The grim reality remains that fog is still a serious hazard for all flight operations -- particularly for smaller aircraft that may lack the full range of technological navigation and landing aids boasted by hi-tech jets.
While jets -- because of their technology -- can attempt 'blind' landings, smaller turboprops generally lack such aids.
Unlike cars, planes do not have the ability to slow down because of reduced visibility -- and even the 19-year-old Fairchild Metroliner that was destroyed on Cork Airport's runway yesterday would have had to land at around 160kph.
Cork has a guidance system called an instrument landing system (ILS), which is the approach aid that the Metroliner pilots used despite being able to see nothing but mist out of their windscreen, to guide them down the gentle glideslope toward the runway.
But at a predetermined point in the descent, known as the decision height, the pilots have to look up from their instruments and make a decision about whether they can see enough of the high-intensity runway lights to be able to make their hand-flown, visually directed landing.
Some passengers at Cork Airport yesterday said the fog was so thick at one point that they couldn't see out the plate-glass windows of the terminal and across the runway.
The Manx2 pilots -- after their second aborted approach -- had a critical decision to make.
They could attempt a third landing or divert to Shannon, Kerry or Dublin Airports.
But the problem was that the fog which had affected Cork was also reported to be swirling around the Clare airport.
When the Air Accident Investigation Unit is able to listen to the pilots' deliberations on the cockpit voice recorder, it will learn more about the reasons why they concluded that they should try a third time.
Until then, the precise cause of Flight NM 7100's disaster will remain as murky as the fog that shrouded Cork Airport yesterday morning.