The Dublin Airport Authority (DAA) has written to An Bord Pleanala seeking changes in two conditions imposed by the planning authority when it granted permission for a new parallel runway last year.

The DAA said that it found that conditions 3 and 5 of 31 conditions set out by the planners "would significantly reduce its operational capacity at peak travel periods and cause delays and inconvenience for airlines and passengers".

Condition 5 stipulates that when the new runway is brought into operation the average number of aircraft landings and take-offs at Dublin Airport, "shall not exceed 65 between the hours of 23.00-07.00."

The DAA said that, currently, an average of 72, landings and take-offs occur between these hours. "Consequently, Condition 5 would not only restrict the new runway's capacity to support future traffic growth at the Airport, but also the Airport's current capacity with regard to schedules."

Condition 3 states that the new runway will not be used for take-off or landings between the hours of 23.00-07.00. The period from 06.00-07.00 in the morning is currently the busiest hour for flight departures at Dublin Airport, while the period from 23.00 until midnight is amongst the busiest for arrivals.

The DAA said the number of departing aircraft during the 06.00-07.00 hour has doubled since 2003 consequently this busy hour is already over-subscribed in terms of slot allocation.

"Since our initial planning application in 2003 the two biggest airlines at Dublin Airport have collectively added more than 110 new routes/services including 70 new routes/services since 2006," it said.

"Not only would these planning conditions restrict flights at the airport below current levels it also has the potential consequence that existing slots could be withdrawn from many operators."