Subject: [NEXTEL-1] Data takes flight-Southwest Airlines will equip its fleet with a pioneering data communications system

From: NEXTEL-1
Date: Wed, 23 Jun 2004 16:24:29 -0400

Data takes flight-Southwest Airlines will equip its fleet with a
pioneering data communications system

News Story by Bob Brewin

JUNE 21, 2004 (COMPUTERWORLD) - Today's commercial airliners come packed
with computers smart enough to land the planes, but when it comes to
air-ground communications, much of the airline industry uses voice radio
systems that haven't changed much since the era of propeller-driven
DC3s.

Vital communications about weather or route changes between pilots and
company dispatch centers, as well as air traffic controllers, run over
narrow-band and often overcrowded voice radio circuits that resemble an
old-fashioned party-line telephone.

When pilots can transmit on one of these VHF air-ground circuits, the
poor quality of the connections and ambient noise often require them to
repeat themselves. Even with repeats, these voice communications are
prone to errors.

Some airlines do use air-to-ground data communications systems, but
current technology provides a connection with a data rate equal to that
of an early-1980s dial-up modem, 2.4Kbit/sec. Although it provides
clearer and more error-free communications, this slow data service
doesn't support advanced needs such as automatic updates of avionics
software. The VHF radio channels that support this data service are also
becoming crowded and harder to access.

Communications companies that serve the airline industry, such as Arinc
Inc. in Annapolis, Md., and Societe Internationale de Telecommunications
Aeronautiques (SITA) in Geneva, have developed a new data service called
VHF Digital Link Mode 2 (VDLM2), which more than quadruples the
air-ground data rate while using relatively uncrowded portions of the
VHF aviation radio band.

But major airlines, still cash-strapped in the wake of 9/11, have been
slow to adopt this new service fleetwide. One exception is low-fare
pioneer Southwest Airlines Co. in Dallas. Southwest plans to equip its
388 planes with VDLM2 by the end of this year and will deploy the
technology on half of them by this summer, according to Brian Gleason,
the carrier's director of flight operations, technical.

When Southwest started operations in 1988, it served
just three Texas cities with a handful of planes. At that
time, it built its own network of ground stations
operating in the upper end of the 108/137-KHz VHF
aviation band, which allowed pilots to place calls to
the company's dispatch center using a touch-tone
keypad. Even though Southwest expanded the
network of ground stations, it still could accommodate
only one voice call at a time, frustrating pilots who
needed to contact the dispatch center for weather
updates or route changes.

To break that logjam, Southwest in January reached an agreement under
which Arinc will provide the airline with VDLM2 service over an
Arinc-owned network of 148 VHF ground stations that cover North America,
says Gleason.  Southwest first considered using the Aircraft
Communications Addressing and Reporting System data service that Arinc
introduced in the 1980s, but it passed because of the service's low
bandwidth and congestion in the ACARS frequency band, which runs from
129.125 to 131.475 KHz.

Dan Pendergast, director of Arinc's GlobaLink Services division, says
the global VDLM2 frequency of 136.975 KHz is relatively uncrowded today
compared with the ACARS frequencies and offers roughly 15 times the data
rate of ACARS. But since VHF channels are only 25 KHz wide, the data
rate is far lower than wideband services such as Wi-Fi, whose channels
are 20 MHz wide, and the VDLM2 bandwidth is slightly less than 1,000
times narrower than a Wi-Fi channel.

Although VDLM2's data rate of 31.5Kbit/sec. (vs. 2.4Kbit/sec. for ACARS)
seems low compared with Wi-Fi's throughput of 11Mbit/sec., Southwest can
pack a lot of information into such a narrow channel, says Gleason.

Southwest uses the VDLM2 service to handle communications between its
dispatchers in Dallas and aircraft captains, both of whom the Federal
Aviation Administration considers responsible for the operation of
flights.

Storm Warnings

Southwest primarily uses VDLM2 for short text messages between
dispatchers and flight crews. Most of those messages are
weather-related, such as instructions on how to route a flight around a
storm. The flight crew also uses the data link to obtain weather reports
for cities they are heading to, saving the crew from listening to an
audio broadcast of weather conditions.
Instead of flight crews waiting until they are in range of an airport's
Automatic Terminal Information weather-service broadcast on a VHF
air-band frequency, crews can use VDLM2 to request weather information
en route, Gleason says. Southwest also plans to use VDLM2 to transmit
high-resolution weather images from NexRad radars operated by the
National Weather Service, he says.

Dispatchers prepare and receive messages using the Hermes Ground Data
Link System developed by the Reading, England-based Rockwell Collins
(U.K.) Ltd. division of Rockwell Collins Inc., Gleason says. Hermes acts
as a specialized e-mail system, parsing and routing messages from the
dispatch center to a cockpit terminal through an aircraft data-link
radio provided by Honeywell International Inc. in Morristown, N.J.

Messages are sent from the Southwest dispatch center to an Arinc gateway
that then sends them out over the network of VHF ground stations. The
network is spaced across the U.S. to allow communications from stations
to aircraft operating at and above 18,000 feet, Pendergast says. Arinc
also operates VHF ground stations at the 59 airports in 58 cities served
by Southwest to provide communications when planes are on the ground,
says Pendergast.

Southwest also plans to use VDLM2 to remotely monitor engines and keep
track of things such as how they're performing, what their temperature
is and how much fuel they're using, says Gleason. This will help the
company manage engine maintenance and ensure that an engine problem
doesn't delay flight turnaround, a key factor in the success of
Southwest, which has the highest aircraft utilization rate of any
carrier in the U.S., says Gleason.

Gleason estimates the cost of installing VDLM2 at about $50,000 per
aircraft, plus a flat fee per month to Arinc, which he declined to
disclose, for "x amount of kilobits of data." The VDLM2 project doesn't
have a classic return on investment, but it will improve operational
efficiency, he adds.

Robert B. Field, a former U.S. Marine Corps pilot and an aviation
consultant based in Chesterfield, Mo., says data communications are much
more efficient and less prone to confusion for pilots than voice
communications are.
Field, who once served as director of the U.S. Navy test pilot school in
Patuxent River, Md., adds that by using VDLM2 to transmit NexRad weather
information to pilots, Southwest could provide them with a level of
detail not available from aircraft radar systems.

Southwest isn't the only carrier to embrace VDLM2, says Pendergast, but
it is the first in the world to equip its entire fleet. Others using
VDLM2 service include Air France, American Airlines Inc., Continental
Airlines Inc., FedEx Corp. and SAS AB. Arinc estimates that more 500
aircraft will use its VDLM2 service by the end of 2004.

SITA has also started to roll out its VDLM2 network, though it's doing
so more slowly than Arinc is. Akhil Sharma, director of aircom services
development at SITA, says his company has installed 30 VDLM2 ground
stations, primarily in Europe, and he agrees with Gleason and Pendergast
that congestion on ACARS channels will be a key factor affecting
adoption of VDLM2.
Gleason says equipping Southwest's fleet with VDLM2 for internal
communications today will help the carrier make an easy transition to a
VDLM2-based air traffic control system planned by the FAA.

The FAA kicked off a VDLM2-based pilot program at its Miami Enroute Air
Traffic Control Center in October 2002, using the technology to exchange
noncritical communications between aircraft and air traffic controllers.
The FAA had temporarily shelved the project for budgetary reasons, but
the initiative is now back on track, and the system could be used
nationwide by 2009 or 2010.

Sharma says that Eurocontrol, the European counterpart of the FAA, will
also require VDLM2 for noncritical communications with controllers in
the same time frame. When that happens, airplanes equipped with $400,000
flight-control computers will finally move from the party-line
voice-call era to the digital data age.

http://www.computerworld.com/mobiletopics/mobile/technology/story/0,10801,93890,00.html?nas=AM-93890

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