In essence, RNP provides a charted course for the pilot to reference during approach or departure. A special data code and database is loaded into the aircraft's flight management computers. The pilot can then select either an on-screen readout of the guidance information, or hook the whole system into the autopilot.
Besides providing precise guidance for approach and departure routes, the technology also gives pilots very good situational awareness through terrain maps that include the airport and the surrounding area. Because RNP also lessens the likelihood of having to enter holding patterns in bad weather, it saves on fuel.
There also is "tremendous redundancy" built into the system at Alaska Air, Finan says. Each craft has two flight management computers, two GPS receivers, two inertial reference systems, as well as an enhanced ground proximity warning system.
But the vast majority of Alaska Air's approaches and departures do not use RNP, and only 70 percent of the carriers' fleet is equipped with the system. Most of the airports served by the carrier have instrument landing systems, which provide good minimums and vertical and horizontal guidance, Sarah Dalton, Alaska Air's director of airspace and technology, tells Air Safety Week. Moreover, while the utility of RNP is maximized at a location such as Juneau, it is not needed everywhere.
>>Contact: Sarah Dalton, Alaska Airlines, (206) 392-6059, email@example.com; Nick Tallman, FAA Senior Program Analyst, (202) 385- 4683, fax: (202) 385-4691