SHANKSVILLE, Pa. — The United States Postal Service said it will offer another Flight 93 pictorial postmark honoring the passengers and crew.

The postmark will bear the image of the Thunder Bell, located at the Flight 93 Memorial Chapel three miles from the crash site. It will be available for 30 days only at the Shanksville post office starting on the sixth anniversary of the terror attacks.

It will be the fifth pictorial postmark offered at the post office commemorating the 33 passengers and seven crew members of the United Airlines flight.

The postmark can be obtained by mail or in person, Postmaster Kathy Bates said.

"I'll start getting calls as soon as it's out," she said.

Last year, the post office got 7,000 requests for the postmark bearing the image of the Flight 93 crew monument, also located at the chapel.

Flight 93 was en route from Newark, N.J., to San Francisco on Sept. 11, 2001, when it was hijacked and crashed as passengers apparently tried to rush the cockpit. All 33 passengers, seven crew members and the hijackers died.

Construction of a $58 million permanent memorial and national park is scheduled to begin by 2009. A ribbon-cutting is planned for the 10-year anniversary of the attacks.