Это cost-saving efficiency. Так они до сих пор на заправщиках (в том числе на KC-10) и летают, без парашютов. Последний абзац статьи из Time:
The Air Force recently detailed changes it is taking following the crash. KC-135 crews will be getting more training to help them deal with dutch rolls. The service is revising flight manuals, beefing up maintenance, and improving rudder controls for the 396 KC-135s still flying. The fleet is also in the middle of a $1 billion refurbishment. But restoring parachutes to the planes—slated to fly until at least 2040—isn’t on the list of improvements.
а может и не было?