Iridium Phones Link Russian, U.S. ATC (Air Traffic Control)
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Iridium used for ATC; Part 1 of 2
by: Discovery94
12647 of 12688
This sounds like very good news, albeit just a beginning.
QUOTE from Aviation Week & Space Technology:
JAMES I McKENNA/WASHINGTON
Russian and U.S. air traffic controllers are using mobile telephones linked through the Iridium satellite
constellation to hand off control of commercial aircraft in the Russian Far East.
Air traffic managers in the U.S. and Russia turned to the $4.85-billion Iridium system to overcome
communications reliability problems that had triggered severe restrictions on the number of flights that could
use three air routes in the region.
The old communications links suffered a variety of problems in mid-1998. Among the most troublesome
were with one link that used "troposcatter" to route calls from the FAA's air route traffic control center in
Anchorage, Alaska, through a facility in Providenya to the Russian air control center in Anadyr, near the
Bering Sea. The problems do not affect communications with aircraft, only between the two centers.
Troposcatter is a technique in which radio waves transmitted from one ground station are bounced off the
Earth's troposphere to a receiving ground station. The technique is not uncommon, and is used to relay
communications into areas in which ground stations have not or cannot be set up. But FAA officials said the
troposcatter link between Providenya and Anadyr began to break down for reasons that still are not entirely
clear.
"We had a continual deterioration of that link between the two facilities," Ronald E. Morgan, acting director
of the FAA's Air Traffic Service, told Aviation Week & Space Technology.
CONTROLLERS TYPICALLY TRY to pass on messages about when and where a flight will transit the
Russian-U.S. airspace border at least 30 min. prior to crossing. But the troposcatter link became so
unreliable, Morgan said, that "in a couple of instances, we had to turn aircraft around and reroute them"
because controllers could not pass handoff messages in time.
Those diversions added up to 2 hr. to the flights and required the aircraft to make unscheduled interim stops
to refuel. "That's a severe impact" to airlines that strive to schedule and route aircraft on fuel-efficient
transpacific passages, Morgan said.
Continued on part 2:
With the communications links so undependable, air traffic officials slashed the number of flights that could
be scheduled across the three routes in question-G212, B244 and A218. The routes had been used by up
to eight aircraft per hour, but on July 1, 1998, air traffic officials in Russia and the U.S. agreed the rate had
to be cut to just two per hour.
The restrictions remained in place until Mar. 24, when FAA and Russian officials agreed to make the Iridium
phone link the primary operational means of passing handoff messages. A test of the link in the preceding
week had proven the reliability of the Iridium connection, Morgan said.
With the new link in place, he said, controllers can handle up to 11 flights an hour on the three routes.
THE RUSSIAN AND U.S. AIR TRAFFIC services are paying $10,000 a month to provide controllers in
Anadyr and Anchorage with Iridium telephone handsets. When a flight must be handed off, a controller dials
his counterpart across the border to pass on the flight information and estimated crossing time and location.
Russia and the U.S. are splitting the cost of the setup, Morgan said, with each paying for the phone calls its
controller's place.
The heart of the Iridium system is a constellation of 66 satellites in low-Earth orbits of 485 mile. Together
with a network of ground stations, the satellites are capable of picking up and transmitting the signal from a
small handset. Designed for high-end business and luxury users, the Iridium system is seeing what FAA
officials said may be its first operational air traffic control use.
Though a minor contract, the FAA Russian utilization of the system gives a boost to Iridium, which has been
hampered from delays in producing the handsets AW&ST March 29, page 23).
Morgan said the Iridium link is a temporary fix. Under a three-year-old contract with the FAA, AT&T
Alascom is to install a downlink ground station near Anadyr to improve the reliability of communications with
Anchorage. The work has been stalled by problems in securing permits and approval from local government
officials in Russia. Morgan said the contractor should begin to install that ground station this month.
Depending on the results of its current use and the cost of future services, however, Morgan said Iridium
could be retained as a backup communications link between Anchorage and Anadyr.
AVIATION WEEK & SPACE TECHNOLOGY APRIL 19, 1999
Page 49
Posted: 05/10/99, 1:51AM EDT as a reply to: Msg 12647 by Discovery94
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