Do Not Resuscitate
Think this is getting off topic now, so this'll be my last post.
I can only speak for the UK, and I've been out of the ambulance service a few years now, but Do Not Resuscitate orders have no place in the pre-hospital environment. If you go into cardiac arrest, and an ambulance crew attends you, they will resuscitate despite the medallion, tattoo across your chest, wife begging you not to, whatever.
Legally, and morally, there is too much to lose by not resuscitating someone who might have benefited, and the legal minefield of ensuring that the patients wishes not to be resuscitated were made in sound mind, really were their wishes etc, is one to be picked across in a less time-critical situation than a cardiac arrest.
As for cockpit crew, realistically what are you going to do? Add your resusc preference to your pre-flight briefing, or have "DNR" embroidered onto your epaulettes??