Large air forces are rare. As a result ten nations (U.S., China, Russia, India, North Korea, Egypt, South Korea, Pakistan, Japan, and Taiwan) have about 60 percent of the combat aircraft in service. But while the U.S. has only 19 percent of the 15,000 combat aircraft in service, they have a far higher percentage of the air combat capability. This becomes clear when you take into account the quality of the aircraft, pilots and support services. Thus just concentrating on who has the most of the latest aircraft does not tell the whole story. For example, Israel does not make the top ten because it only has 244 active combat aircraft while number 10 Taiwan has 286. But the Israeli aircraft are not only all updated (and sometimes enhanced) F-15s and F-16s, but Israeli pilots are the most well trained and combat experienced in the world. Israel has lived in a war zone for over half a century and its combat pilots know that being the best is a matter of life and death for themselves and Israel as a whole. So the 414 Egyptian combat aircraft put it at number six on the top ten list but decidedly beneath Israel when it comes to combat capability.
If you adjust for aircraft, pilot and support quality the top ten is more like U.S., Russia, China, India, Israel, South Korea, Japan, France, Taiwan and the UK. Pakistan, Egypt and North Korea fall out of the top ten, depending on how you rate each nations qualitative characteristics. Moreover those adjustments for aircraft, pilot and support quality leave the U.S. with up to 50 percent or more of the combat capability instead of just 19 percent of combat aircraft.
Precise values for the number of active aircraft are much easier to calculate than the value of each nations’ aircraft, pilot and support quality. After a war it is relatively easy to determine these values because you have lots of data on aircraft and pilot performance. “Support” includes ground crews, intel, command and control (AWACs and so on) and a lot of other factors that do make a difference. Measuring that support quality is difficult even after a war but when you examine in detail the activities of air forces in combat you cannot avoid the importance of this support in keeping the aircraft flying and equipped with superior information about the situation and their opponents.
The values for quality vary over time. During the Vietnam War the U.S. Air Force found that its new and improved air combat doctrine (all missiles, no guns and so on) left it far less effective against the foe than during Korea or World War II. Even during those two wars the quality value fluctuated from year to year. Since Vietnam American air power fixed lots of problems and has had an unprecedented period of air supremacy. But that is always subject to change. For example, American air warfare commanders are very concerned about how much the massive Internet based spying efforts by China and Russia have reduced the American qualitative edge. According to the above analysis the U.S. has 4 to 7 times the combat power of China or Russia, but if there have been heavy data losses to China and Russia, the U.S. would only have a 2 or 3 to one advantage against either nation.