As no commission report could ever do, the terrorist acts of September 11, 2001, have galvanized the United States. More than six thousand people died in New York—one of every thousand workers in the city. Taking over a commercial aircraft to use it as a piloted cruise missile evidently exploited a terrible vulnerability of modern society. No commercial pilot could be induced by threats to do this, but the imagination of public officials did not encompass those willing and even wishing to die to kill hundreds or thousands of others.
This instrument of kilo-terrorism is fragile; it can be defeated by not much more than a sturdy locked cockpit. The terrorist planners knew this and went to the trouble, and risked the vulnerability, of planning at least four such hijackings within minutes of one another—too little time to spread the word effectively throughout the aviation system.
My purpose here is to discuss threats and not primarily solutions, although the two are interlinked. If hijacking a passenger aircraft will no longer work, motivated terrorists will doubtless choose something else. I have heard from at least six of my colleagues proposals, for example, to modify the aircraft flight control system so that the pilots can irrevocably switch control to the ground. Or to program the aircraft to automatically land at the nearest suitable airport. Such remedies are unnecessary and distracting. It is enough to lock a strengthened cockpit door and to make all understand that it would not be opened even if hijackers kill the passengers and cabin crew. Clearly, once the aircraft radar transponder is switched to emergency or hijack mode, it should not be possible to switch it back until the aircraft has landed. There is a case to be made for improved 1990s-era crashproof recorders that will capture video and audio from the cabin as well as the cockpit.
Both smaller and bigger terror weapons exist, and their use may be expected. But even if we have seen the end of hijacked passenger jets as cruise missiles, that is not the end of their equivalent—the use of rented or stolen cargo jets as piloted cruise missiles. Opportunities range from large fleets such as those of UPS or Federal Express to the hundreds of 707s and even 747s available for lease at airports in the United States and elsewhere. More skill but less violence would be involved in stealing such an aircraft. It might be used against buildings or against operating nuclear reactors, which are not designed to withstand the impact of a jumbo jet at high speed. It is relatively simple to have an automatic radar that shuts down a nuclear reactor if a high-speed aircraft is detected within a few seconds of collision; but even in that condition a reactor might suffer a core meltdown because of interference with the emer-gency core cooling system and other engineered safeguards.
Thomas Friedman in his New York Times column of September 25 characterizes the new type of terrorist as evil,…
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