March 19,2008: A U.S. Air Force RC-135 aircraft has set a record, spending over 50,000 hours in the air since it entered service in 1962. The main reason for all those hors in the air is that RC-135s are very good at what they do, and have been much in demand of late. The RC-135 is a flying vacuum cleaner of electronic signals. Built on the same airframe as the KC-135 tanker and Boeing 707 airliner, it carries two dozen people to operate all the electronic gear. Exactly what kind of electronic signals the RC-135 can pick up is classified, but apparently includes any electronic device the enemy in Iraq or Afghanistan is using. Costing about $4,000 an hour to operate, only 15 of them are in service.

Periodically, the air force has to remove KC-135s from service because of metal fatigue problems (usually in the wings, or with the pylons that attach each of the four engines to the wings.) All 732 KC-135s were built between 1956 and 1965. The Boeing 707 commercial transport is actually a civilian version of the original KC-135 (which itself evolved from the World War II B-29 heavy bomber.) Over the decades, the KC-135 fleet has undergone constant repair and reconstruction. New engines, and new structural components have been added, as older items wore out, or showed signs of wearing out faster than anticipated.

The problem with older aircraft is that you never know what's going to go next. The KC-135s are carefully scrutinized for metal fatigue, which is, so to speak, the "silent killer" of aircraft. Better diagnostic tools, like scanners that allow careful examination of components without tearing apart portions of the aircraft, as well as new sensors that can be installed in the aircraft itself, keep the KC-135s flying safely. With current technology, it's believed that the KC-135s and RC-135s could be kept going at until 2040. In the case of the RC-135, any similar sized aircraft would do as a replacement. And that's how the next generation RC-135 is being put together.

The RC-135s get even more attention, mainly because they have proved particularly useful over Iraq and Afghanistan. There, the RC-135s collect a wide variety of electronic signals in an area, and analyze them quickly. The analysis effort is looking for patterns. The bomb teams leave signs electronically (cell phones, walkie-talkies) or visually (images captured on surveillance cameras). Using the right math and analytical tools (software and computers) and you can quickly discover where the bad guys are coming from, and have the ground troops promptly raid the location.

This kind of work is popular with the RC-135 crews, because they are getting a chance to do, in a combat zone, what they have long trained for. Moreover, it's relatively risk free, as the aircraft fly beyond the range of machine-gun or should fired anti-aircraft missiles. In addition, the most productive work is done during night missions, when the bad guys can't even see the RC-135's high above.

But when these RC-135s land, the ground crews know what to look for, and what components may need some extra attention. With decade's worth of maintenance records, patterns emerge, and the crew chiefs get to know each RC-135 very unique "personality."