US procedures for designing precision approaches based on aircraft required navigation performance (RNP) are to be adopted by the International Civil Aviation Organisation as global standards, says the US Federal Aviation Administration. The procedures have been used by the FAA to develop the first public RNP approach, to Washington DC’s Reagan National airport.

FAA associate administrator for aviation safety Nick Sabatini says ICAO’s Obstacle Clearance Panel recommended in November that the US procedures be adopted as the worldwide standard for developing RNP approaches. The standard is expected to be approved in June or July, and will include the FAA’s operational approval document, which has just been signed off for publication as an advisory circular, the agency says.

Unlike previous special RNP procedures developed by Alaska Airlines, the public RNP approach to National’s runway 16 can be used by any authorised carrier with suitably equipped aircraft and trained aircrew. The approach, which follows the Potomac River, reduces decision height to 475ft (145m), from the 720ft minimum allowed with the current offset localiser approach available in poor weather.

So far, only Alaska is using the new procedure, flying the first RNP approach to National on 28 September. Out of 10 approaches flown, three were “saves” – landings that would otherwise have been diversions – says vice-president flight operations Kevin Fanin.

The FAA has since converted a special RNP approach to San Francisco airport into a public procedure, and plans to develop RNP approaches at 25 more airports during the 2006 fiscal year. These include new procedures to deconflict approaches to New York’s Kennedy and LaGuardia airports, and Chicago’s Midway and O’Hare, in poor weather.

JetBlue Airways will be first to use the Kennedy procedure, to be available in March, and will operate the first Airbus aircraft approved for RNP approaches. A procedure at Portland, Oregon, planned for February, will be used by Alaska subsidiary Horizon Air, which will be the first regional airline with RNP approach capability, Sabatini says.

The majority of public procedures the FAA is developing are to RNP 0.3 – meaning the on-board navigation system must keep the aircraft within a 0.3nm (0.55km)-wide flightpath box. The National approach is RNP 0.11 (0.11nm/0.2km) because of the proximity of prohibited airspace over the US capital. RNP 0.3 approaches can he hand-flown, but RNP 0.11 requires use of the autopilot, says Sabatini.

Some 30% of the US airliner and large business jet fleet can meet the RNP 0.3 standard, while a smaller number are RNP 0.11, the FAA says, adding that the majority of the fleet is expected to be RNP-capable after 2015.


Source: Flight International