Four non-fatal accidents and 14 serious incidents involving Irish-registered commercial aircraft were reported last year.
The combined total of 18 incidents and accidents — despite the absence of fatalities — is the highest level since 2007.
The IAA said the majority of these accidents and incidents occurred outside Ireland and were subject to investigations by other aviation authorities.
In addition, six light aircraft accidents were reported to the IAA in 2011, four of which involved Irish-registered aircraft, and two serious incidents, while light helicopters were involved in three non-fatal accidents.
The IAA also recorded three non-fatal accidents and one serious incident involving microlights.
The IAA did not include the airplane crash at Cork Airport on Feb 10, 2011, in which six people died in its published figures, as it involved a Spanish-registered Metroliner aircraft.
It was the only fatal commercial aircraft accident in Europe last year and the worst fatal airline accident in Ireland in four decades.
The aircraft, which was operating a flight for the Isle of Man-based Manx2 airline, crashed as it attempted to land at Cork Airport in fog on a flight from Belfast.
The accident is still the subject of an ongoing inquiry by the Department of Transport’s Air Accident Investigation Unit.
The IAA said there were no fatal accidents involving 670 Irish-registered commercial aircraft last year which completed more than 660,000 flights, involving over 1m flying hours.
The non-fatal accidents included the collapse of an nose landing gear on an ATR twin-engine turboprop on landing at Shannon, an injury to a child who fell from an aircraft stairs, damage to an aircraft landing gear while taxiing, and an overheated landing gear brake unit which required the precautionary evacuation of an aircraft.
However, the level of runway incursions at more than nine per 100,000 aircraft movements in 2011 is the highest level recorded in recent years, although over half are considered not to pose a significant safety risk.
The IAA noted that the global fatal accident rate of between four and five per 10m flights has remained largely static over the past few years. The average for flights in Europe is below two per 10m flights.
The IAA said analysis had shown that controlled flight into terrain (usually in foggy or low cloud conditions) and loss of control have been the most common contributory factors in all fatal accidents in Ireland over the past six years.
Abnormal runway contacts are the principal factor in non-fatal accidents and incidents.
Kevin Humphreys, IAA’s director of safety regulation, said the authority was satisfied there was a good reporting culture among Irish aviation professionals, with more than 7,300 incidents received last year.
The most commonly reported incidents are events in aircraft cabins, failure of components, and bird strikes.