Some seats on American Airlines jets stay empty for safety.

UNDATED - Some seats on American Airlines flights will remain empty for at least a month while the airline and federal regulators investigate a shortage of life rafts on some airplanes.

For at least a month, American Airlines will leave some seats empty on these 767s.

The airline, restricting the number of passengers because of a shortage of life rafts.

Scott Shankland of the Allied Pilots Association says "now what concerns me is that is took several years to discover the problem."

The union that represents American's pilots questions why the company and the FAA didn't notice the problem in 2007 when the airline changed the number of seats on the jets used mostly on flights to Europe and South America.

Scott Shankland says "AMR management's standard response to things like this is it's not a safety issue. But it clearly is."

The company has declined to talk about the life rafts on camera.

But in a statement says "this issue of compliance never endangered passenger safety."

Veteran pilots we talked to disagree.

Denny Kelly, an aviation safety consultant, said "the passengers were at risk because there wasn't enough life rafts."

Airline safety expert Denny Kelly says the U.S. Airways landing on the Hudson River shows why rafts are important.

They keep passengers dry, unlike life vests that could force passengers into frigid water.

Denny Kelly says "you can't offset life rafts with vests or seat cushions you can't do it."

Now the FAA is asking questions.

A spokesman telling us, "we are working with American Airlines to make sure they have enough life rafts on board."

The FAA also says its inspectors will also look at whether American Airlines violated any federal safety regulations, and they'll decide whether to take any action against the company.