I have been in this scenario. 911 was the first call placed during a life threatening dive accident, which resulted in air ambulance being sent to our location. DAN was not contacted until the 911 call was completed, and so there was no possibility of DAN arranging the evacuation.
After the dust settled, I called my claim representative to inquire whether DAN would consider reimbursing the cost of this air ambulance service as it had not been pre arranged by DAN. I was told that it was correct to call 911 first in life threatening situation, and that DAN would process the air ambulance claim along with all other claims submitted related to the accident.
Several times during the claims process, I repeated this question when speaking with DAN and was always assured that DAN would process the air evacuation claim if primary insurance did not cover the bill.
The evacuation bill was ultimately fully covered by primary insurance, and so I don't have a way to know with 100% certainty that DAN would have covered the substantial cost of air evacuation in this case. But I was given no reason to think DAN would not have covered the bill and DAN did pay out on all other claims submitted and not covered by primary insurance.
This is only my experience, best to contact DAN directly with this question to get the correct answer.