We have already presented two responses on this intriguing but controversial question. Here is another response from one of the leading experts on impact phenomena, David Morrison of the NASA Ames Research Center:

"It is certainly possible for a meteorite to strike a commercial airliner, although the probability is low. We can make a very rough estimate by comparing the area of airliners with the area of cars in the U.S. A typical car has an area on the order of 10 square meters, and there are roughly 100 million cars in the U.S., for a total cross-sectional area of about 1,000 square kilometers. The typical airliner has a cross-sectional area of several hundred square meters, but the number of planes is much smaller than the number of cars, perhaps a few thousand. The total cross-sectional area of airliners is therefore no more than 10 square kilometers, or a factor of at least 100 less than that of cars. Three cars are known to have been struck by meteorites in the U.S. during the past century, so it would appear that the odds are against any airplanes having been hit, but it is not impossible that one might have been.

"To my knowledge, there have been no reports of airplanes being struck, however. If one were hit, it would be more likely to occur on the ground than in the air, because airplanes spend more time overall on the ground. And finally, even if one were hit in flight by a meteorite, it would be unlikely to cause an explosion of the sort that ended the flight of TWA Flight 800 last year."