You don't need a doctor or medical assistance if you are fatigued, you need sleep, and then possibly a few days off.
Discretion should take into account
all crew members' fitness to fly. A sector that a tired flight deck might be able to safely do - sitting down pressing buttons and drinking coffee, might be very difficult for a cabin crew member who has to be on their feet for the whole sector continually speaking and serving hundreds of passengers. Given an edict that discretion will be used, it takes a very brave cabin crew member to break ranks and refuse to work - especially since by not working they know they will cause their colleagues even harder work. So they work fatigued. Given a flight emergency, such as a decompression, emergency evacuation, or flight crew incapacitation; are those cabin crew going to be able to perform to the highest level of safety?
"Safety is our highest priority" the airlines say...............
Discretion is used by the airlines to save money, we need to remember that.
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