The grounding of hundreds of F-15s because of dangerous structural defects is straining the nation's air defense network, forcing some states to rely on their neighbors' fighter jets for protection, and Alaska to depend on the Canadian military.
The F-15 is the sole fighter at many of the 16 or so "alert" sites around the country, where planes and pilots stand ready to take off at a moment's notice to intercept hijacked airliners, Cessnas that wander into protected airspace, and other threats.
The Air Force grounded about 450 F-15s after one of the fighters began to break apart in the air and crashed Nov. 2 in Missouri. An Air Force investigation found "possible fleet-wide airworthiness problems" because of defects in the metal rails that hold the fuselage together. It is not clear when the F-15s will be allowed to fly again.
Compounding the problem created by the grounding, another fighter jet used for homeland defense, the F-16, is in high demand for Iraq operations. And the next-generation fighter, the F-22 Raptor, is only slowly replacing the aging F-15.
Military officials say they moved quickly to patch any holes in the homeland air-defense system, and they report an increase in air defense sorties in the past month, using replacement F-16s. But they acknowledge difficulties.
"When you're filling in, obviously it's going to cause some strain," said Mike Strickler, a spokesman with North American Aerospace Defense Command, or NORAD, which is operated by the U.S. and Canada. "You're spreading resources a little thinner than we would like."
But air defenses have not been compromised, Strickler said. "We can be anywhere at any time," he said.
With the F-15s in Massachusetts out of commission, the Vermont Air National Guard is covering the whole Northeast. The Minnesota Air National Guard is manning sites in Hawaii. In Louisiana, the Illinois Air National Guard has been filling in.
And with Oregon's fighters grounded, the California Air National Guard is standing watch for the entire West Coast, an area of more than 300,000 square miles that is home to more than 46 million people in California, Oregon, Washington, and slices of Arizona and Nevada.
The California Air National Guard said this is first time in history that a single state's fighter wing is providing coverage for an entire coast.
The California Guard is keeping three alert sites — in Riverside and Fresno, Calif., and Portland, Ore. — equipped and staffed with pilots and mechanics.
"As a unit we're kind of stressed, but everyone's accepting this as a challenge and all the men and women of the unit are acting as professionally as you could ever hope for," said Col. Gary Taylor, operations group commander for the Fresno-based 144th Fighter Wing of the California Air National Guard.
The unit has had to borrow F-16s from bases in Indiana and Arizona and trim back training for certain overseas operations.
A relatively small number of F-15s — the model known as the F-15E Strike Eagle — were not found to have the structural problem, and are unaffected by the grounding.
For three weeks in November, Canadian CF-18s filled in for the F-15s over Alaska. Several times, the Canadian fighters scrambled to "do an identification" of Russian bombers flying exercises outside U.S. airspace near Alaska, said Maj. Mike Lagace, a Canadian military spokesman for NORAD.
"We flew up, met with the long-range patrol, basically let them know, `Hi, folks, we're here too,'" Lagace said. Russian warplanes have been flying exercises near Alaska and Canada with increasing frequency in recent months.
Now, a brand-new squadron of F-22s based in Alaska is standing in for the state's grounded F-15s, said Tech. Sgt. Mikal R. Canfield, a spokesman at Elmendorf Air Force Base.
As for the F-15 pilots in Portland who have been largely idled by the no-fly order, they have told the visiting California airmen they are eager to get back in the cockpit.
"They're thankful for our help," said Col. Ryan A. Orian, the 144th Fighter Wing's vice commander. "But they'd love for us to leave."