December7, 2006: Military aircraft have been taking electronics (or "avionics) into the air for nearly a century now. But aircraft are a hostile environment, and there are still unexpected problems. Some of them you just live with. For example, the U.S. Navy's E-6B electronic warfare aircraft use a lot of old equipment, largely because the aircraft has been in service since the 1960s. Some of that stuff wears out real fast, like the ARN-84 navigation system, which has to be replaced (and repaired) after about 36 flight hours. The navy finally bit the bullet and got a new, more robust navigation system (the ARN-153) to replace the older one.

Often, a system designed to be durable, turns out not to be, for unexpected reasons. The F-18 altimeters were wearing out faster than expected because of unanticipated vibration. Vibration is a common problem with avionics, and the altimeters were fitted with a shock-absorbing tray to eliminate the problem (and save several million dollars in repair and replacement costs each year). Helicopters have these problems as well. A computer on the MH-60 had a tiny leak in a seal, that led to the units becoming unreliable after about three years. Finding and fixing that problem is now saving several hundred thousand dollars a year.

New aircraft are particularly prone to these unanticipated problems. Better computer modeling, and testing methods in general, have made the problem manageable. That's important, because avionics have become a larger and larger component of aircraft cost. Without these improvements in modeling and testing methods, aircraft would become inoperable. This was often a major risk with aircraft that were at the bleeding edge of technology. The SR-71 was one example, as was the Russian MiG-25. The new F-22 and F-35 would not be possible using the design and quality control methods employed a few decades ago.