Boeing weighs costs and lives. (Dilemma).

Deciding whether to lay off employees used to be the toughest decision a CEO faced. But times have changed, and for some chief executives the true gut-wrencher is no longer about hiring and firing. It's about life and death.

When two missiles were launched from the shoulder of an alleged Al Qaeda terrorist at an Israeli jet as it left Mombasa, Kenya, on Nov. 28, U.S. airline executives had to accept that one of their jets could be next. That forced the manufacturers of those jets to weigh a difficult equation: The cost of equipping jets with antimissile shields -- estimates range between $800,000 and $3 million per plane-versus the cost of doing nothing.

"How do you do an effective cost analysis when you're talking about human life?" Philip Condit, Boeing's CEO, asked recently at a luncheon of Boston College's Chief Executives Club. "How do we do it?"

It's an especially sensitive subject for the 61-year-old Condit, a licensed pilot who has turned Boeing, now Chicago, into the world's largest aerospace company. The jet those missiles narrowly missed in Kenya was a Boeing 757-300 carrying 271 passengers and crew. Since the attack, experts have speculated that only one airline, El Al, the national carrier of Israel, has an antimissile system on some planes, and that U.S. airlines and manufacturers simply don't have the resources to equip all their planes. At least not without help.

Condit, when asked if it's even possible to make a passenger jet missile-evasive, hinted that not only was it possible, but that talks on the subject were under way.

"The aerospace industry has made a lot of defensive tools for military aircraft," says Condit. "Some of them are pretty effective, and pretty expensive. In the end, this is about how to best address the security/safety issue and how to best use resources. Between us, the government and military, those are the kinds of decisions we'll have to work together on."