The US Air Force spends more money every year to keep an old -- and sometimes archaic -- fleet in the air. More funds for sustaining the fleet means less money is available to buy new airframes. Of course, flying newer aircraft is the only way to solve the first problem, so figure that one out.
But, if you think that's bad, take a quick look at readiness levels for the French Air Force (tip: G2 Solutions).
The French-language Secret Defense blog extracts fleet availability data from a report prepared by a member of parliament, revealing the dire situation of the French Air Force. The figures do not directly compare to the USAF's mission capability rate.
Here's a cleaned-up Google translation of the analysis of the data by Jean-Dominique Merchet, the journalist for the Liberation newspaper and editor of the blog.
One air force fighter aircraft out of two (48.3%) is not available. This huge figure, is extracted from a report prepared by the parliamentary deputy Jean-Claude Viollet. And, contrary to official statements, these figures are increasing. The availability rate by type of aircraft is detailed in the table below. An aircraft is considered unavailable when it can not be implemented within six hours. The difficulties stem mainly reactors [ed: translation unclear]. Specifically, the Air Force has the ability today to fly 150 combat aircraft. In the first half of 2007, there were, for example, 26 Mirage 2000-Ds available. If one excludes the six 2000-D Opex (three in Afghanistan and three in Djibouti), it means that the Air Force is able to bring only one squadron (20 aircraft) out of three it is supposed to possess.