Aircraft Noise Ombudsman report finds no benefit in full-length take-offs at Perth Airport

The Aircraft Noise Ombudsman published a report in October 2012 regarding a proposal that aircraft taking off from Perth Airport should use the full length of the runway, rather than using partial length takeoffs.

It concluded that there is “no significant or discernible difference in noise for Perth residents when full length departures are used for jet aircraft.”

Full-length takeoffs had been considered over many years as a potential method of reducing aircraft noise in surrounding areas.

In August 2011, Qantas provided the Perth Airport Noise Management Consultative Committee (ANMCC) with information from a trial of full length departures compared to those that departed from a taxiway intersection point partway along the runway. Data from this trial did not indicate any difference in noise impact on the ground.

In May 2012, Steve Irons MP lodged a letter with the Aircraft Noise Ombudsman about the proposal for increasing the number of ‘full power’ and/or ‘full length’ runway takeoffs.

Full power takeoffs were previously considered by the Perth Airport Noise Management Consultative Committee (ANMCC), and dismissed as being inconsistent with aircraft manufacturer’s recommendations.

The Aircraft Noise Ombudsman analysed data collected during July 2012 , again comparing full length runway departures and departures from an intersection, when different runways were in use.

Airservices Australia technical modelling showed that in theory, a full length takeoff may result in a 3.75 decibel reduction in noise at the airport boundary, but the noise reduction benefits decreased with distance, to the point where the sound difference was not discernible. The extra height gained by an aircraft conducting a full-length takeoff varies according to weight, performance, takeoff thrust and weather conditions, and is therefore not easy to compare. Theoretical modelling showed a height difference of only 60-75 metres when comparing a full-length takeoff with an intersection departure.

The report found that full length departures for all jet aircraft would also have a number of disadvantages:

Reduction in airport capacity due to lack of aircraft being ready for departure from the intersection points.
Additional fuel and CO2 emissions due to additional taxiing distance and potential delays due lack of capacity mentioned above.
Potential safety implications due to additional runway crossings on Runway 03. This is because the taxiway from the international terminal does not go all the way to the runway threshold, and aircraft would have to cross the runway at taxiway Lima and proceed to the full length from the other side of the runway.