Two KC-135s tankers were involved in fatal crash over Iraq

First, formation flying is difficult under most circumstances, let alone with giant fuel tankers in a combat zone. White knuckle stuff if you watch enough air-to-air refuelling videos. Any tanker-jet drivers out there to comment?

Second, one of the aircraft had a second crew aboard in training, which is unsettling given the above, and that there are numerous non-combat theatres in which trainees could be accomodated rather than in a combat zone.