Air Defense: Another Cover Your Butt Exercise


p> March 29, 2007: The U.S. Department of Homeland Security is still wrestling with the issue of defending airliners against missile attack. The latest idea, which is to be tested, is to have a UAV circle major airports, at about 65,000 feet, and use sensors to detect missile launch, and then employ a laser to disable the missile. Lots of technical problems involved, because of how far away (over 20 kilometers) the sensors, and laser, is.

U.S. government efforts to get airlines to equip their aircraft with anti-missile equipment has run into one obstacle after another. The main problem is that there have been so few missile attacks on commercial aircraft (none in the U.S. or Britain, and very few anywhere else). So the airlines are reluctant to equip their fleets with the expensive (a million dollars or more per aircraft) systems. The airlines know that these anti-missile systems will add to the maintenance burden (the systems have been used by military aircraft for years, and have a maintenance track record). It's another complex item that can fail, and delay a flight. The cost will add a few dollars to each passengers ticket, and will take aircraft out of service to have the systems installed. There's also the potential for lawsuits from damage done when you get a false alert. The systems are so expensive because they use lasers to blind any missile (rather than flares, used in older systems, and even more of a problem when there is a false alarm.) The airlines believe that such systems might, in the end, cause more of a threat than they protect everyone from.

Terrorists trying to take down airliners with portable missiles has been a threat for a long time. Actually, over the last four decades years, it's been a reality. Some three dozen commercial aircraft have been shot down by such missiles. However, the downed aircraft have tended to be small, and most of these tragedies have taken place in Africa. The wars in Africa are the worst on the planet, so violent that most journalists avoid them. For over three decades, this has kept the use of portable missiles against civilian aircraft off the front page.

Larger airliners, like the Airbus's, and 757s, 767s and 747s, have not been brought down because these missiles were not designed to take on aircraft with such large and powerful engines. While these missiles were originally intended for use against jet fighters operating over the battlefield, the reality turned out to be different. The most likely targets encountered were helicopters, or propeller driven transports. These aircraft proved to be just the sort of thing twenty pound missiles with a three pound warheads could destroy. Against jet fighters with powerful engines, the missiles caused some damage to the tailpipe, but usually failed to bring down the jet. This was first noted during the 1973 Arab-Israeli war, where the Egyptians fired hundreds of SA-7 missiles at Israeli A-4 light bombers. Most of the A-4s, with their 11,187 pounds of thrust engines, survived the encounter. Larger jets, like the F-4 and it's 17,000 pound thrust engines, were even more difficult to bring down. Smaller commercial jets, like the 737 or DC-9 (each using two 14,000 pounds of thrust engines) have proved vulnerable. But a 757 has much larger engines with 43,000 pounds of thrust, and the 747 is 63,000 pounds. Moreover, the rear end of jet engines are built to take a lot of punishment from all that hot exhaust spewing out. Put a bird into the front of the engine and you can do some real damage. But these missiles home in on heat, and all of that is at the rear end of the engine. But as long as the threat is there, bureaucrats will feel pressured to do something, if only to cover their own butts.

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