The Federal Aviation Administration is dramatically expanding its Air Marshal operation, posting job openings on its Web site and fielding hundreds of calls from interested candidates.

Since last Tuesday's attacks, FAA offices in Washington have been flooded with more than 100 calls a day from law enforcement personnel and ordinary citizens who are eager to learn more about the Air Marshals program, according to spokesperson Rebecca Trexler.

"They say how willing and ready they are to do this hazardous duty," she said. "It’s very heartwarming, and another example of heroism coming out of disaster."

A job announcement was also posted on the FAA Web site Tuesday, and applications are now being taken online, Trexler said.

Applicants must have U.S. citizenship, be under 37 years old, willing to work irregular hours, be on call 24-hours a day, endure limited contact with family and travel to places that run a higher risk of terrorist attack.

Salaries for Air Marshals range from $35,100 to $80,800. And since marshals must also be anonymous to passengers, the FAA is also seeking candidates who represent a mix of sexes, races and ages.

The program’s safety and operation policies may vary, but every candidate must also undergo extensive background checks, as well as psychological and physical tests.

Qualified candidates will undergo an elaborate training program that includes outdoor ranges with moving targets, a 360-degree live-fire "shoothouse," an indoor laser disc "judgment pistol shooting" interactive training room and a close-quarters training room with protective equipment and dummies, according to the FAA site.

Not everyone thinks Air Marshals are the answer. Some doubt the marshals' ability to handle highly organized, multiple-hijacker terrorist threats like those that took place last week. Others question the safety of keeping any kind of firearms on board civilian aircraft.

But advocates say that's better than nothing.

"If there is going to be a gunfight inside the cabin of an aircraft, it’s highly likely that innocent people are going to get shot," said John Greaves, an attorney and former airline captain. "But if you think about the alternative, it’s a no-brainer. This is by far the lesser of the other potential evil."

Other experts want to change how the program works. Attorney and security expert Charles Slepian believes marshals should ride with the crew in the cockpit, rather than with passengers in the cabin.

"If we had a camera system in airplanes, all of which is technology that is readily available, the marshal could transit photos back down to the ground to terrorist specialists, and he could get some help in his decision making," he said.

Trexler says marshals can become involved when unruly passengers threaten the safety of a flight. "They are trained to handle all types of disruptive behavior scenarios, but marshals can’t reveal their cover unless absolutely necessary," Trexler said.

The number of marshals employed, where they train, and what weapons they carry are all confidential.

"We don’t want to give the bad guys any information to calculate their odds," Trexler said. "They just need to know these marshals, who are highly trained and will use lethal force if necessary, are out there every single day."

The Air Marshal program was first established in the 1970s to stop a rash of widely publicized hijackings on flights in and out of Cuba. The program dropped from public view as the hijackings diminished, but was never abolished.