"Listening in on messages passed over ACARS, the venerable air transport data link, is a pastime for hobbyists trying to track flights on PC screens at home. It isn't easy--they often get it wrong. But in the post-9/11 environment, the airlines are establishing a security standard which would prevent such activity. The U.S. Air Force, which is equipping with ACARS to maintain access to airspace, is likely to be a major beneficiary."
And the Air Force rings in:
"The Air Force is less than happy with current ACARS security provisions. "If you do a Google search on ACARS, Web sites pop up where you can see hobbyists that intercept messages and post them to the Internet," says Capt. William Cobb, program manager for airborne networking with the U.S. Air Force Research Lab (AFRL). Hobbyists are a fairly benign group, but others with a scanner, a personal computer, ACARS decoding software and Internet access may not be. The military no doubt faces more sophisticated and determined threats.
"It's essentially an open link, Cobb says. "If you know what you're looking for, it's easily interceptable." He points to Web sites such as http://uk.groups.yahoo.com/group/acarsonline, devoted to posting intercepted ACARS traffic. Others offer free ACARS decoders, real-time message feeds and explanations of decoded messages.
"AMC doesn't pass any classified data over the link. Nor would it use ACARS for sensitive-but-unclassified information relating to cargo or passengers until stronger security is in place. "It's an operations security issue," Kassander says. The service doesn't want to telegraph intent. "If you throw in information that may be available on ACARS, AOC-type messages [relating to cargo and origin/destination], you can start to put together a picture of what types of operations may be going on." Although AMC wanted a security solution yesterday, it puts a high priority on interoperability, on getting a standard that all vendors can build to."
You can read the whole article online at: Securing ACARS: Data Link in the Post-9/11 Environment
So, if they secure ACARS can the HFDL system not be far behind?
Thanks to Glenn Blum and the UDXF list for this heads up.
Also there is a companion article in this edition of Avionics you should also check out at Military ATM: Meeting Civil Standards by David C. Walsh.