But the TSA disputes the claim, saying it altered the weapons training six years ago because marshals needed more of a police-type training program rather than military-style weapons instruction.
The TSA said in an e-mail that "the course of fire and minimum qualification score air marshal candidates must acquire is the same today as it has been for over six years."
To replace departing air marshals, the TSA hired internally, including some administrative staff who had no college, law enforcement or military backgrounds, one current marshal said.
"To me, it's more of an embarrassment to be a member of that agency that would allow that particular individual in the training program," one marshal said. "I wouldn't want them on my flight. ... I don't want them as my partner."
The revelations come in the wake of a CNN investigation, in which air marshals and pilots said that only about 1 percent of the nation's 28,000 daily domestic flights were protected by onboard, armed federal marshals.
The Federal Air Marshal Service disputes that figure.
CNN's report about the declining number of marshals on planes also got the attention of Congress.
In a congressional hearing this week, the head of the Transportation Security Administration, Kip Hawley, told members of Congress that what CNN heard from the air marshals is wrong.
"I have to just correct on the factual basis on the CNN report about air marshals covering 1 percent. That number is absolutely wrong by an order of magnitude, and it was a guess by the folks there, and I just have to say that number is completely false."
Hawley would not say what percentage of flights has air marshals. That's a national security secret.
The service hides behind national security to keep the public from knowing how thin coverage really is, air marshals said.
The Federal Air Marshal Service continues to refuse CNN's request for an interview.
This month, Democratic Rep. Sheila Jackson Lee of Texas, who serves on the Homeland Security Committee, began holding closed-door meetings with the air marshal's service to determine whether congressional oversight committees are getting the truth.
"We will keep working and continuing to make sure that the airlines are served with the appropriate law enforcement that ensures the safety of the traveling public. We, too, are not interested in having funny numbers," Jackson Lee said.
Jackson Lee said that the committee has not finished its work and that she is convinced American air travel is safe for passengers. "It is important to restate and to re-emphasize: This is not an open opportunity for those who would attempt to do Americans harm. We are light years from where we were in 2000. We have trained personnel. They're being utilized, and we feel that we are steps ahead of where we were, but we want to get better. And that's what we intend to do."
After seeing CNN's initial report, Democratic Sen. John Kerry of Massachusetts sent a letter to Homeland Security chief Michael Chertoff asking for clarity on the number of air marshals protecting domestic flights and sought a response by April 11.
The senator is still waiting, Kerry's staff said.