Originally Posted by
tdracer
I'm puzzled by this, and the apparent 'rush' need. The current E-6 aircraft are not all that old - 1990 EIS - and the 707 airframe is known to be pretty robust (same structural technology as the KC-135 that's been flying far longer). The CFM engines are pretty much the same as on the KC-135 as well. I don't get what's so worn out that it needs urgent replacement.
The 707 is a shinning example of the classic analog instrumentation - which by it's nature has far better EMP resistance than modern electronics. In contrast, the C-130J is basically a glass cockpit.
1990 is quite a few years ago and the 1950’s when the 707 was designed are even longer ago and 707 based aircraft (JSTARS, AWACs and Mercury) are rapidly running out of life. Yes they have been well maintained and cared for, but support, spares, fatigue, and technology have caught up.
As for those questioning speed and altitude, TACAMO really does not need either. They are not intend to operate in contested airspace. Lazy, cruising patterns are the mission, which the herc can do all day (and already did). If you want low risk and 4 engines, hard to argue.