For the Comanche, did he get a number to call? I try to enforce the idea that declaring an emergency is a really good idea but the goal is to prevent the emergency in the first place. Also, I've known of those that made similar mistakes in their past, just being dumba$$e$. Basically they scared themselves silly and had plenty of time to review their life as it passed before their eyes. The FAA response, ATC through FSDO, has generally been 'go and sin no more.' You know his tail number, if he does it again, if he's not dead, in steps the FSDO. Possibly a call to the rental place? "Just want to make sure he's okay."
Something similar happened to a friend. IMC + Bad weather, low ice level, night approaching, and a VFR only pilot in a rental asked for departure clearance out of the "C". The departure controller gave him the VFR clearance, and a latest doom and gloom PIREP. The guy taxied, did the runup, and called for takeoff.
The controller turned to the sup (my friend and also owner of the airplane) and asked what to do. The sup responded "you clear him for takeoff" knowing full well that he would most likely not see his airplane or that pilot alive again.
The guy took off, declared an emergency and got vectors to a nearby airport 6 minutes later. An hour later he departed again, emergency, vectors, made it 20 miles that time. He repeated it again a few more times, about 30 minutes between emergencies.
Somehow the guy made it to his destination. The controllers only documented the flight assists, warned the next facility he was coming, and left the guy to the sup.
In the conversation later, the guy told his story. His son and pregnant daughter-in-law had just been in a near-fatal motorcycle accident up north, he was trying to get there before his son died. He knew driving was too slow and he wasn't thinking clearly. He did make it in time, his son regained consciousness for a short period of time, and died the next morning. I don't know what the final FAA response was other than he never rented from the sup's place again.
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In the case of the Merlin, "Are you requesting an IFR flight plan?" I know I've stopped students from saying stupid things on the radio before, even in Merlin-class aircraft. In the phone call afterwards, "were you aware you were on a VFR clearance?" I've also known sectors to not pass flight plans along, pilots to screw up, and controllers to accidentally hit VFR instead of IFR for codes.
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For the buzz job fellah, again a similar situation encountered in the past, the pull-ups were going through the tower's airspace. The tower response was to involve the Safety Program Manager (SPM) at the local FSDO. He came out to the EAA crowd, cowboys and all, and gave an excellent presentation during one of their meetings. The good guys were so identified and got some great instruction and door prizes (a handheld GPS was given out). One of the cowboys told the SPM off. That's fine, don't violate the airspace and we'll leave you alone. Violate the airspace and we'll be back wearing the black hats.
The buzz-jobs continued. Two weeks later an Inspector, wearing a black baseball cap with FAA lettering, was standing on the roof of the restaurant with a clipboard and binoculars. He flew in to that airport in his Harmon Rocket and did a 'buzz-job' with self-announcing on the unicom, even saying hi to the gal monitoring unicom.
The buzz-jobs stopped violating the airspace with one exception. That exception is now fighting certificate action.
Fly SAFE!
Jedi Nein