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.
I wonder if a modified KC-46 could fill the USAF doomsday mission (used to be Looking Glass on KC-135). Not sure how many airframes would be needed, and the E4 would seem to be too expensive.