Dealing with an incapacitated flight crew member is something that should be in every airline's SOPs. I am rather taken aback by the lack of a single contribution which starts "our airline's SOPs are to do ...."
It is. I briefly described mine, sorry I didn't specifically say it was the SOP.
4. Concerning the trope that only a registered medical doctor may determine death in England and Wales and the US and other countries, prima facie it rather misses the interesting point, which is: what do you do if it happens in your presence? It is a question which most people who put themselves out of quick access to medical services (for example, most people who go sailing, backpacking, trecking, rock-climbing, mountaineering, cross-country skiing, even hunting and angling) are wise to ask themselves, and indeed such guidance is available.
Generally, it's:
1. Secure incapacitated pilot away from controls.
2. If possible, remove pilot to other suitable area (usually the galley)
3. Page for onboard medical assistance while commencing first response
4. Purser or other crew to remain in flight deck to assist remaining pilot if only 2 crew operating
5. Contact outside assistance (for airlines that use Medlink)
6. Continue first response in consultation with outside advice & any onboard professionals
7. Assist travelling companions/family of the patient (if applicable)
CPR if conducted may only cease when:
a) Definbrillator advises to discontinue
b) Doctor onboard pronounces death
c) extreme danger to the crew performing CPR
d) On flights with only a few crew, the crew become too tired to continue
e) The flight lands and ground medical services take over
f) signs of life return
She says check pulse, breathing, maybe eyes (iris contraction), but that there is no single indication that someone is dead. Lack of iris contraction indicates brain damage of some sort, but one cannot thereby conclude that the victim is dead. She says that resuscitation must always be tried. But of course she operates in a relatively unconstrained situation.
As pointed out earlier we are legally unable to pronounce someone dead, even a doctor onboard can only pronounce death and not certify death. For this reason in my current outfit it's called "presumed death" and we are not allowed to fully cover the face of the deceased in case they are in fact under some other condition but not clinically dead.
Most large airlines do have equipment onboard to deal with a presumed death in flight (clean-up equipment, body bags, places to stow a deceased person, etc etc)
There are also procedures which deal with this but I won't go into them here; suffice to say we are going to treat the person with as much dignity as possible given the situation.