A light aircraft crashed killing two friends after the engine cut out because there was not enough fuel in the tanks, air accident investigators have found.
Flight instructor Niall Doherty and advanced learner Damien Deegan, both 31, died when the Cessna 150H came down in scrubland a short distance from Birr airfield, Co Offaly.
Investigators found that the engine stalled as the men took off because of fuel starvation.
Other factors identified by the Air Accident Investigation Unit (AAIU) were a failure to maintain adequate airspeed after the engine quit and inadequate fuel management.
Investigators warned they were concerned that Mr Doherty may have been suffering from fatigue.
There were five hours and 10 minutes of recorded training flights on the day of the accident on November 11 last year, with little break in between, on top of the instructor's trip down from Dublin.
But the AAIU said it could not assess if this would have played a part in a miscalculation of fuel or reaction to the engine stall.
Estimates found that only 9.6 litres of fuel was left in the plane - 3.65 litres below the recommended minimum - after the pilots carried out a third circuit of the airfield and a touch-and-go before the crash.
The AAIU found: "It is therefore likely that, with a nose-up attitude during climb out, one or both fuel tank outlet ports became uncovered and that air entered the fuel supply lines, thus causing fuel starvation."
It said further evidence for this was a lack of fuel at the crash site and the fact that the engine was stopped at impact.
No mechanical or technical defect was found.
Witnesses reported hearing the engine make a loud noise as the Cessna climbed before it appeared to cut out and the plane plummeted to the ground 350 metres from the runway in a plantation of saplings.
The two friends had been flying circuits with the grass landing strip in sight when they came down.
The AAIU said the noise from the engine before it stalled is frequently symptomatic of a sudden fuel/air mixture.
"The investigation is therefore satisfied that the cause of the engine stoppage was fuel starvation due to an inadequate fuel quantity remaining in the fuel tanks," it found.
The Reims-Cessna 150H, first registered in 1998, was used by the Ormand club as a training plane, and nicknamed The Crow.
The aircraft conducted six flights on the day of the accident and refuelled shortly after 2pm. The accident happened at about 4.44pm.
Mr Deegan, from the village of Crinkle near the airfield, was almost at the end of his pilot training and was understood to be planning to get a commercial licence.
Instructor Mr Doherty had worked as a commercial pilot in the past and taught at the club.
The investigation determined that an attempt may have been made to bring the plane around to the airfield after the engine stalled but that was against club rules.
The report found that the decision may have been taken due to the plane's proximity to the landing strip and the altitude, but that it was unlikely it could have made it.
The AAIU said it wanted the Ormand club to publish more specific instructions on necessary fuel loads and to amend its record of flights to include fuel uplifts and fuel on board prior to each departure.
It said it was concerned that the level of supervision and oversight of the club's activities was inadequate and issues had not been picked up by an Irish Aviation Authority inspection in 2011.