NADIN

NADIN is an acronym that stands for National Airspace Data Interchange Network. It was used by the airlines to input flight plans into the National Airspace System (NAS). These flight plans are routed to the relevant air traffic control sites. But I first heard of NADIN from one if it's failures. The Availability Digest had a short write up on a multi-hour outage:

"Without a filed flight plan, a commercial airliner can’t fly. This was painfully demonstrated on Thursday, November 19, 2009, when the FAA’s1 National Airspace Data Interchange Network (NADIN) failed at about 5:30 AM Eastern Time and was down for three hours..." 

The system processed an average of 1.5 million messages per day, but by 2002 was already obsolete and was beginning to break down due to technical issues. In August of 2008 a single corrupt file header took out the system for 90 minutes. In 2009 the head-end in Atlanta crashed three times. Other government agencies were concerned the aging system wasn't hardened against "terrorist cyber-attacks." Eweek published the following stinging comment

"International intelligence analytical firm Stratfor reported a similar system outage back in 2000. Another was reported in June 2007 in addition to the Aug. 21 and Aug. 26 crashes. Those are the ones we know about; we don't know how many others were never made public information."

NADIN was an old-school mainframe based telecommunications network designed to aggregate and distribute air traffic  data. First proposed in 1975, the system went live in 1989 on a pair of Phillips DS714 mainframes.  It was intended to integrate the Aeronautical Fixed Telecommunications Network (AFTN) and their "Service B Network" because those were " near saturation." Remember this isn't just radio communications this is also the filed flight plans!

 Management of NADIN was awarded on a non-bid basis [source] to ASQ, Inc in 2002. This awarded contract included both NADIN1, and it's packet switching network (NADIN2). But what really needed to happen was a full replacement. In 2009 that happened. Lockheed Martin engineers built a more robust and redundant virtualized system on a series of  Stratus FTserver 6400s. Whew.