Hi Fouga,
The skipper, and author of the letter, is still serving in the Air Corps while the copilot has since moved on. I believe they may have been on an Air Ambulance flight when the item was spotted. Interestingly it was also spotted by many people on the ground. This was also around the same time that there was much hype over the Aurora project and the spooky goings on at Machranish in Scotland.
There was also another case that sort of included the Air Corps. It was something to do with a Garda on patrol in the Bundoran area who spotted strange lights. He thought it was the Finner heli out training and rang to confirm but the lads were tucked up in bed. I cant remember if the aircraft was launched to search for the source of the lights but nothing was ever found.
I do know there have been many sightings reported to the Air Corps but most turn out to be normal. One case I remember was a report of a high altitude object shining in the sky after sunset. As the reporter drove along it was stationary but when he stopped it seemed to notice and moved off. A look at his path while driving and a call to Dublin ATC showed that his track was quite close to that of the evening flight to Sligo. His movement compared to the aircraft was reletively zero but when he stopped it moved away, i.e. it was moving all along. the shining was simply that the aircraft at high altitude was still catching the evening sun even though the ground below was in darkness. A simple but effective optical illousion!