So, that is a very good question.I'm in and out of BOS (and EWR, JFK, LGA, IAD, PHL) single pilot in a Seneca a few times a week. The big airports aren't just for the big boys.
Besides, it's easy to be a hero when you have a crew, and a dispatch department and catering and flight attendants, and baggage handlers, etc.
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That said, any 63 year old with a stuffy nose can make a mistake. WTF was his FO when he went to take off without a clearance?
Fix
I do often fear the composition of crews these days. It's often an old guy (sometimes recently x-Airline) and a young guy (often fresh off a 172). While that might seem like a good mentoring opportunity, more often than we'd like, it's the senile-complacent leading the blind.
I've personally flown with several recent airline captain retreads who freaked out during garden variety visual approaches ('cause no ILS was entered into the box and no 8 mile final was ever gonna happen).
I've personally flown with recent flight school graduates who knew neither basic aerodynamics nor much of anything more about turbines than the fact that don't possess propellers.
Our side of the aviation industry includes many outstanding airmen. However, the new hire situation has grown frightful.