The Effects of Arming Pilots
"The airlines' liability waiver is incredibly broad and could be read to relate to circumstances not related to guns, even if it's forgetting to set the flaps at takeoff," said Kristin Rand of the Violence Policy Center, a gun control group in Washington.

An earlier version of the bill gave airlines immunity from claims arising from pilots' conduct in defending against criminal violence or air piracy. The immunity in the final bill is much broader. It would apply whenever a pilot used or did not use a gun.

"They've weakened the airlines' responsibility for security," said Marc S. Moller, a New York aviation lawyer who typically represents plaintiffs. "And the airlines are being given a free pass for other sorts of breaches, too."
http://www.nytimes.com/2002/07/14/national/14PILO.html