Datalink Expands in Oceanic Airspace

A key building block for NextGen and comparable ATC modernization efforts is replacing voice radio with digital datalink messages for most ATC communications. Controller-pilot datalink is being introduced this year in Europes upper airspace, and all aircraft in core EU airspace must be equipped for it by 2015.
No firm schedule has yet been set for the United States, and datalink is one of the NextGen elements apparently being pushed further into the future by FAA due to funding limitations.

Except, that is, for oceanic airspace. Back in the 1990s the worlds major ANSPs got together to develop a FANS (Future Air Navigation System) controller-pilot datalink to replace unreliable high-frequency (HF) radio communications in oceanic airspace. FANS uses satellites to transmit messages between planes over the oceans and the ATC centers on shore that oversee specific oceanic flight information regions. Initially, intercontinental flights kept track of their positions, and reported them via HF radio, using their inertial navigation systems (since there is no radar over the oceans). But in recent years, ADS-C has enabled GPS navigation as well. With more accurate location information reported via datalink, it is feasible to reduce in-trail spacing on oceanic routes from the traditional 50 miles to 30 miles. That opens up more airspace, and makes it easier to let planes change altitudes en-route for optimum fuel consumption.

The newest development, announced last month, is truly global coverage for satellite transmission of datalink messages. Iridium, which operates a constellation of 66 low-earth-orbit communications satellites, received FAA certification to use that system for ATC datalink purposes (rather than just for pilot-dispatcher communications). That is a major development, for two reasons. First, it extends controller-pilot datalink to the polar regions, where the current Inmarsat communications satellites do not provide coverage. Second, the Iridium equipment needed on aircraft costs about one-fourth as much as an Inmarsat box.

FAA certification was granted after year-long field trials involving Cargolux 747 freighters, Continental Micronesia 737s, and Delta 737s and 757s. The Wall Street Journal reports that Australia, Japan, and the U.K. are close to certifying the Iridium system as well. New long-haul planes will soon come with such equipment built in, and one supplier of Iridium boxes foresees a retrofit market of as many as 10,000 aircraft.

Datalink is a critically important component of the new paradigm for air traffic management. Its unfortunate that oceanic and European airspace will be making routine use of it long before domestic U.S. airspace.

Contact
Bob Poole
From
Reason Foundation
Website
www.reason.org
Date

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