Two factors have been cited as major reasons why the 3rd Wing took a drubbing. None of the participating American aircraft had the latest long-range AESA radars, although some of the F-15Cs of the Wing had this equipment. A decision had been made beforehand not to send the AESA equipped planes to India due to the additional maintenance package required to support them. A total of six F-15Cs were sent to India, each equipped with a fighter data link, short-range AIM-9X heat-seeking air-to-air missiles, and the U.S.'s helmet-mounted cueing system.
Secondly, at India's request, the U.S. agreed to mock combat at 3-to-1 odds and without the full range of capabilities of simulated long-range radar-guided AIM-120 AMRAAM missiles. U.S. fighters could not use the active on-board radar capability of the AMRAAM, and the missile was limited to around 32 kilometers range and required the use of the F-15C's onboard radar to target Indian aircraft. In standard use, AMRAAM has a range of over 100 kilometers and is a fire-and-forget missile that doesn't require additional guidance from the F-15. Practiced tactics by the F-15 crews mix two AESA-equipped F-15Cs with two stock aircraft. The AESA aircraft take long-range missile shots to thin out and disrupt the formation of a numerically superior force before the two sides close up for closer fighting.
The F-15s flew in groups of 4 against packages of 12 Indian Air Force aircraft consisting of a mix of Mirage 2000, Su-30, Mig-21, and Mig-27 aircraft. The Mirage and Su-30 aircraft were used in the air-to-air role, while the Mig-27 was used as the strike aircraft with the Mig-21 providing escort to the Mig-27s. The Indians also had a simulated AWACS platform and the use of simulated active radar missiles such as the AA-12 and the French Mica, unlike the F-15Cs. This gave the Indian Air Force a fire-and-forget air-to-air missile capability that the U.S. fighters didn't have, a heavily unrealistic assumption in actual hostilities.
However, the U.S. pilots admitted that they did have problems with the simulated active missile threat and don't normally train against launch-and-leave threats. They also admit they underestimated the training and tactics of the Indian pilots. Indian air force planners never repeated failed tactics and were able to change tactics as opportunities became available, mixing things up and never providing the same tactical "look." Some of the Indian aircraft radars had different characteristics than U.S. pilots had seen on stock versions of the aircraft, including some of the Mirage 2000s.
More details have come out about the "losing" performance of U.S. F-15Cs (from the Alaska-based 3rd Wing) against India's air force in the "Cope India" air-to-air combat exercise earlier this year. The Air Force and some members of Congress have used the "failure" of American aircraft to further justify the need for new F/A-22 and F-35 fighters. Some are calling the results a dramatic example of weakening of American air combat capabilities