Initially, the Boeing KC-135 was being considered because the versatile design could also fulfill a yet-unspecified aerial refuelling role.

[1] Although a "purpose-built" aircraft would have suited the RCAF requirements better, an opportunity to acquire Boeing 707s as an alternative, soon presented itself.

[3] The first four aircraft had been built for Western Airlines, but that order was subsequently cancelled; the fifth was bought separately a year later.

The CC-137 fleet had a combined total of 191,154 hours, remaining in service in the transport role until 1995, with two aircraft continuing in use as tankers until 1997.

[4][5] Most of the fleet ended up with the Northrop Grumman E-8 Joint STARS programme either for spare parts or conversion to E-8C standard for the United States Air Force.