I have some experience with -135s and parachutes.
As a new 2Lt in KC-135s we were required to wear parachutes during air refueling operations (at least when the Standardization check folks were onboard
). Four months into my ops flying career we were refueling F-4Cs flown by new fighter pilot students. One young 1Lt managed to get himself into a PIO under our boom and hit us in the aft left fuselage, removing almost all the boom, putting a crease in the left stabilizer and tearing up the leading edge of the left elevator. We pitched over to -1.5G but the autopilot stayed connected (not supposed to with that pitchover) and pulled us back to straight and level. Although the experienced boom operator tried to bail out the aft hatch, we were still pressurized and he could not open the hatch. Resulted in a landing at Edwards with no hydraulics and manually cranking down the gear and flaps. And some awards and decorations for a safe recovery. The F-4 student had previous problems with fighter upgrade and ended up as a co-pilot of a B-52.
As a result of the accident investigation it was determined that ALL previous C-135 accidents where bailout was possible were successfully recovered. ALL previous C-135 accidents that involved a catastrophic collision or failure resulted in NO successful bailouts. After that, SAC removed the requirement for wearing parachutes during operations and they were carried only on the aircraft sitting on nuclear alert duty.
We carried parachutes on the RC-135 long past the SAC KC requirement but a review of all operations determined that the weight of 34 chutes, required periodic inspections, and availability of only two hatches (fore and aft) for bailout would not result in successful bailouts except under conditions that would allow the aircraft to be recovered. The chutes were recovered. The EP-3E collision in April 2001 also showed that even a fairly severe collision could be successfully recovered.
Hence, no parachutes are carried on RC-135s and haven't been carried for many years.
Seems odd that this would be raised on a site with lots of former RAF types as the V-bombers were woefully deficient in having ejection seats only for the pilots, especially as a retired navigator. I had one flight in the Vulcan as a college student/journalist and was not comfortable with the lack of a seat during the low-level portion. I was not bothered by the lack of a parachute during my one flight in a Nimrod R.1.