Alaska Airlines expands RNP in Alaska


Having pioneered the use of RNP at Juneau in the mid 1990s, Alaska Airlines is expanding its use of Required Navigation Performance precision approach technology to land aircraft in Adak, AK, and, in March, Ketchikan. The technology, growing in popularity and usage exponentially over the past few years in the US, allows airlines to follow more direct, RNP-guided approaches limiting weather diversions and saving fuel.

RNP technology provides computer-plotted landing paths with pinpoint accuracy by using a combination of onboard navigation technology and the Global Positioning System satellite network. It allows aircraft to fly safer, more reliable landings, and reduces reliance on ground-based navigation aids.

"Since …the mid-1990s, the system has been credited with saving thousands of flights from diversions or delays each year due to poor weather and airport equipment outages," said Sarah Dalton, Alaska Airlines' director of airspace technology. "The next-generation flight guidance technology benefits passengers and the airline by providing additional flight safeguards and reducing fuel consumption."

The improved procedures in Ketchikan will allow Alaska Airlines to land more precisely and with lower visibility minimums. Since 1996, Alaska has introduced similar RNP procedures at 45 percent of the airports it serves in Alaska as well as in Washington DC; Portland, Ore.; and Palm Springs, Calif. The airline is the only major US carrier with a fully equipped RNP fleet and fully trained crews.

Another positive step after recent breakthrough with WAAS

The news follows subsidiary Horizon Air's historic flight on 30-Dec-2009, when the airline flew the first scheduled-service passenger carrier service Wide Area Augmentation System (WAAS) technology. The flight, on the airline's popular Portland-to-Seattle route, was flown by one of Horizon's 76-seat Bombardier Q400 turboprops.

An aircraft utilizing WAAS can, in some cases, land in adverse weather conditions with as little as a half-mile of visibility at 200 feet of altitude - conditions that would deter aircraft not similarly equipped.

WAAS builds on Horizon's previous advances - made in conjunction with its sister airline, Alaska Airlines - in Flight Management System (FMS) technology, such as Required Navigational Performance (RNP) and Global Positioning System (GPS) satellite networks. In 2006, Horizon became the first regional carrier to be certified for RNP approaches, which use a combination of onboard navigation technology and GPS. WAAS takes that a step further by using additional satellites that monitor GPS satellite signals; it then corrects for any errors in GPS satellite position.

The new WAAS instrument approach is known as "localizer performance with vertical guidance" (LPV). Unlike RNP approaches, which are only available for use at airports after an extensive certification process, WAAS approaches can be used at any airport where the navigation database has been updated.

There are now more LPV approaches available in US airspace than Instrument Landing Systems (ILS) approaches, which involve using an older, ground-based radio signal system for landings in lower-visibility weather. One LPV advantage is that it doesn't rely on ground-based equipment susceptible to outside factors such as weather or power outage.

Currently, Horizon has one WAAS-equipped Q400, with a flight management system developed by Universal Avionics, a manufacturer of advanced avionics equipment based in Tucson, Ariz. The Federal Aviation Administration (FAA) has agreed to support WAAS upgrades on six more Horizon Q400s. In return, Horizon will provide the FAA with flight data on 300 legs of flying, so the agency can determine the full value of WAAS technology.

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