A six-month test of customised required navigation performance (RNP) approach procedures in Australia could help accelerate wider use of practices that would boost efficiency and safety. RNP arrivals allow trained and equipped crews and aircraft to fly procedures that minimise track distance and increase safety using a mixture of satellite and inertial navigation system (INS)-based guidance.

The benefits can be amplified when an airline customises the procedures for a particular aircraft type. Starting this month Qantas, Virgin Blue, Jetstar Airlines, Airservices Australia and USA-based procedure designer Naverus will participate in a trial to demonstrate "that RNP terminal procedures can co-exist in the traditional environment", says Chris Henry, performance engineering manager for Naverus.

Co-existence of RNP and traditional arrival procedures has been a problem in the USA, where six airlines use customised procedures for arrivals or instrument approaches. Industry officials say that during busy periods, air traffic controllers are hesitant to upset a flow pattern by allowing one airline to fly a special procedure that other carriers are not qualified or equipped to fly.

Traditionally the US Federal Aviation Administration has been the procedures developer, but private companies such as Naverus and Jeppesen are increasingly being hired by carriers or airports to design approaches and the FAA then has to examine them for approval. "Quite a few people want to do this," says Jeff Williams, manager of the FAA's RNAV/RNP group, adding that there is a "horrendous growing need" in the international market for the RNP procedures, both for arrivals and satellite-based instrument approaches.

As such, the FAA is finalising a programme that will allow private companies to develop, flight check and maintain RNP procedures, as well as help airlines gain FAA approval to use them. This would boost the rate at which procedures can be developed. The FAA has created 37 RNP terminal area procedures so far and plans 25 more this year, but these are public and not optimised for any particular carrier's operations. US airlines worry that their approved procedures will be worthless if controllers will not allow their use.

Henry says the Australian test will make use of "blended" arrival procedures at Queenstown that will have a branch point where RNP-qualified aircraft can take a more efficient route without affecting other traffic.

Source: Flight International