At the request of the Transportation Department's top official, the agency's inspector general on Tuesday said he will investigate policies at JetBlue and American Airlines that led passengers to be stranded aboard planes for several hours this winter during storms.

"I have serious concerns about airlines' contingency planning that allows passengers to sit on the tarmac for hours on end," Transportation Secretary Mary Peters said in a statement. "It is imperative that airlines do everything possible to ensure that situations like these do not occur again."

Peters asked Calvin Scovel, the Department of Transportation's inspector general, to examine why JetBlue passengers were stranded aboard a plane at New York's John F. Kennedy International Airport during the recent Valentine's Day storm, which caused the airline to cancel about 1,000 flights and sparked a massive corporate mea culpa campaign.

She also asked Scovel to examine a December incident in which American Airlines passengers were forced to stay on a plane for more than six hours.

Peters said the investigation would look into airlines' polices on extended delays and make recommendations for how to prevent such events.

"Passengers have a right to know what to expect when it comes to ground delays," she said.

Scovel said in a statement that his invesigation would provide "a thorough and objective assessment so that corrective actions can be taken by the appropriate parties to prevent such situations from happening again."

JetBlue has been on the defensive after stranding passengers in planes at JFK for up to 10 1/2 hours earlier this month. The airline adopted a customer bill of rights after the disruptions, and has been scrambling to restore its reputation with passengers.

Last week, the Air Transport Association, which represents most major passenger and cargo carriers, said the Federal Aviation Administration should allow delayed flights to come back to terminals so passengers can exit planes without forcing those planes to lose their place in line for takeoff.

Shares of JetBlue were down 44 cents, or 3.5 percent, at $12.31 in afternoon trading on the Nasdaq Stock Market. Shares of American parent AMR Corp. were down $2.31, or 6.4 percent, at $34.06 on the New York Stock Exchange.