COURTESY TECH. SGT. SHANE A. CUOMO U.S. AIR FORCE / 2006 The Hawaii Air National Guard grounded its fleet of F-15s yesterday after a crash prompted an order worldwide to stop flying the planes except for those on alert. Here, F-15 Eagles get a last-minute check before taking off from Hickam Air Force Base for a training exercise.

F-15 jets grounded

A training session ending with a crash has spurred a search for structural flaws

The Air Force grounded its fleet of F-15 Eagle interceptor jets yesterday, including those belonging to the Hawaii Air National Guard, but the Hawaii jets will be maintained ready to launch to respond to any air threats, said the state adjutant general.

An Air Force spokeswoman in Washington, D.C., said yesterday that the country's fleet of 676 F-15s, including mission-critical jets, have been grounded for "airworthiness concerns" after a plane flown by the Missouri Air National Guard crashed Friday during a training exercise.

In a statement Sunday, the Air Force said preliminary findings indicate a possible "structural failure" on the aircraft.

The Air Force issued a statement yesterday broadening the grounding order worldwide, including bases in Hawaii, Japan, England and the Middle East.

In Hawaii the 17 F-15 Eagles belonging to the Guard's 199th Fighter Squadron are responsible for the air defense of the islands, including any airborne terrorism threats.

"The only F-15s authorized to fly are those on alert status," said Maj. Gen. Robert G.F. Lee, who as adjutant general commands the Hawaii National Guard. "We will not be flying them for routine training until they figure out what went wrong in the Missouri flight."

Pilots and crews in the 199th Squadron are on alert status around the clock, ready to take off within minutes of a defense alert, as they did Sept. 11, 2001.

The Hawaii guard has models A, B, C and D F-15 aircraft, which indicate production dates from 10 to 20 years ago, Lee said. They are scheduled to be replaced in 2010 by F-22 Raptors.

The plane that crashed was a C-model fighter assigned to a Missouri National Guard wing based in St. Louis.

Col. Robert Leeker, wing commander, said Friday the plane had been among four planes split into pairs and engaging in one-on-one training flights in which speeds of 400 to 450 mph are typical. The other planes returned safely.

A 10-year veteran of the guard whose name was not released ejected from the aircraft before it crashed in Dent County, Mo. The pilot, who suffered a dislocated shoulder and broken arm, was released Saturday from the hospital.

In June an F-15 jet from the Oregon Air National Guard went down in the Pacific Ocean during a training mission. And in a separate incident in June, an F-15 crashed near Eielson Air Force Base in Alaska.

The F-15 was originally manufactured by St. Louis-based McDonnell-Douglas, which was purchased by the Chicago-based Boeing Co. about a decade ago. Boeing delivered its last F-15 to the Air Force in December 2004 but still manufactures the aircraft for other customers.