In some circumstances, a less-lethal stun-gun or bean-bag gun might be preferable to using a firearm, Slate said, although he did not know whether the marshals had access to such equipment.
Whatever their training, Slate said he hopes the federal government re-examines how it prepares air marshals to handle people with mental disorders.
"Unfortunately . . . crisis drives policy," he said.
Inland law enforcement officials say they train new officers in handling mentally ill people along with the other police-academy courses in firearms, use of force and search and seizure.
There are about 30,000 flights per day into and around the United States, Thomas said. Anywhere from 5 percent to 7 percent of the daily flights across the nation are carrying air marshals, and most of those are international flights, he said.
"If you fly from Ontario to Cleveland, it's more likely you are not going to have an air marshal on the plane, because its not a high-risk flight," Thomas said.
Most details about the Federal Air Marshal Service are closely held. The group has forbidden its members to speak publicly about their jobs and reveals only basic and generally vague information about their methods and training.
Adams said air marshals get two courses on dealing with passengers who act strangely. The first comes during a seven-week program at the Federal Law Enforcement Training Center in Artesia, N.M. That program is a basic law enforcement session. They get more specific training on unruly passengers later at a training center in Atlantic City, N.J.
Adams said the training deals with strange behavior, but when strange behavior takes a more threatening posture, lethal force quickly becomes an option.
The air marshals date back 30 years to the sky marshal program created to deter hijackings of flights to Cuba.
When terrorists hijacked four planes on 9/11, fewer than 50 marshals were available to guard flights each day.
In November 2001, the newly formed Transportation Security Administration was given 10 months to expand the air-marshal program from a few dozen to several thousand.
According to the General Accountability Office, the investigative arm of Congress, the rapid ramp-up led to shortcuts on training and security clearances. Air marshal training, designed as a 14-week program, was cut to five weeks for candidates with no law enforcement experience. Others had just one week.
In recent years, the Federal Air Marshal Service has sent active officers back for training on some of the skills that were skipped initially.
POTENTIAL FOR CONFLICT
Thomas, the air security author, said that without more information about Wednesday's shooting, it was hard to say whether the Miami air marshals acted appropriately.
Thomas said he expects the number of onboard confrontations between troublesome passengers and air marshals to increase, especially after a planned Dec. 22 relaxation of rules that prohibit air travelers from bringing some types of short-bladed scissors and tools on board airliners.
"If we don't upgrade the training of flight attendants and air marshals to be prepared to be deal with these permitted items, situations like (Wednesday's) will become more frequent," he said.
Adding to the potential for conflict is the rising incidence of air rage and increasing frustration among air passengers, he said.
Data show a direct relationship between the number of onboard disturbances involving passengers and the number of complaints air travelers lodge with the federal Department of Transportation, he said. In recent months, complaints jumped 30 percent as travelers griped about overbooked flights, delays and long waits tied to security, Thomas said.
Huntington Beach firearms instructor Greg Block, whose firm trains law-enforcement agencies, said air marshals lack some of the tools and resources police on the ground can utilize.
Police officers can use their uniformed presence, verbal commands, and other tools such as batons and pepper spray to try to control a situation. They also can call for backup, an option obviously not available to marshals once they're airborne.
Federal officials say Rigoberto Alpizar made the threat in the jetway, after running up the plane's aisle from his seat at the back of the jetliner.
But the report concluded that the air marshals had to act quickly, regardless of whether Alpizar actually had a bomb.
Officials told ABC an Egyptian man was stopped at New York's John F. Kennedy Airport a week ago with a pair of shoes that tested positive for an explosive substance.
They train for accuracy with paintball guns inside mock airline cabins. They use bullets designed to stop and expand in flesh to minimize damage to an aircraft.