With hundreds of US F-15 Eagle jets now grounded because of dangerous structural defects, the country's air defence network is becoming strained somewhat, particularly as Russia has chosen this time to adopt a an aggressive posture in the air space surrounding Western countries. The F-15 forms the backbone of the fighter command at many of the 16 or so "alert" sites around the United States, where planes and pilots are at a constant standby to take off at a moment's notice to intercept unidentified aircraft in the nation's airspace. The US Air Force grounded about 450 F-15s after one of the fighters began to break apart in the air and crashed in the US State of Missouri in November. An US 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. A relatively small number of F-15s, the F-15E Strike Eagle, were not found to be affected, and have not been grounded. For defence operations managers, the problem is compounded by the fact that the replacement fighter, the F-16, is already in high demand for operations in Iraq, while the state-of-the art next-generation fighter, the F-22 Raptor, is only being inducted into service very slowly and is not available in sufficient numbers. According to US military officials, they have patched in holes in the nation's air defence system quickly, so that no security risk exists. However, the act of spreading resources thinner across the system is also proving to be a strain. For the sensitive outpost of Alaska, which borders Russian airspace, Canadian CF-18s Hornets filled in the void for three weeks in November. The Canadian fighters scrambled several times, to "do an identification" of Russian bombers participating in exercises outside US airspace near Alaska. They report that Russian warplanes have been flying exercises near Alaska and Canada with increasing frequency in recent months. Currently, a brand-new squadron of F-22 Raptors based in Alaska, is standing in for the grounded F-15s.



