Helicopters and light airplanes flying in "uncontrolled airspace" are to be the subject of new regulations to ensure an aircraft can no longer crash without an alarm being raised.

Two men – pilot Colm Clancy (34) and flight student Dermot Sheridan (24) – died last week after the helicopter in which they were flying hit power lines over bog land in Co Kildare.

Even though the chopper left Weston Airport in Dublin at 5pm on Wednesday, its disappearance was not known about until the following morning, more than 12 hours later.

The Sunday Tribune has established that no guidelines or procedures were broken and that it is not unusual for aircraft to leave smaller aerodromes without giving either a destination or an estimated arrival time.

However, the Irish Aviation Authority (IAA) said it was reviewing the practice with a view to ensuring a similar tragedy was not repeated.

Although the two men on board the stricken helicopter are thought to have died instantly, the possibility that their injuries may not have been immediately fatal has not been ruled out. In that case, a search-and-rescue operation could possibly have saved their lives if it had started in time.

A spokeswoman for the IAA said: "There was a delay and we need to establish what exactly has happened. It is perfectly legal for a light airplane or helicopter to operate in uncontrolled airspace and responsibility for search and rescue then falls to the pilot.

"All of these areas will now be looked at while we await any recommendations that may come from the Air Accident Investigation Unit. We will be looking at this ourselves and this whole area is something the authorities are now actively examining. The Irish Aviation Authority has to find a balance to ensure a procedure that is satisfactory and safe."

A spokesman for the European Helicopter Academy, which owns the crashed helicopter, said the company had already launched a review of its operations to ensure the delay in search-and-rescue would not be repeated.

The spokesman said: "The company principals have met with the Air Accident Investigation Unit to discuss exactly what happened, and the flaws of the system.

"There will be changes as a result of this because the gap between the time they left and the time they were found is obviously a concern. It is clear there are questions: some track could be kept and if the flight then doesn't report back, the alarm could be raised. It would appear from what the air accident people said that the two men were killed instantly. There is no question that they were injured and there for a long time.

"As dreadful as this situation is, if that had been the case, it would have been even more devastating – if possible – for the families affected by this awful tragedy."

Weston Executive Airport – the aerodrome in West Dublin from which the flight took off – issued a brief statement saying that air traffic control there had acted correctly and followed all guidelines.."