Just wondering, as I'm working on my PPL during a hot summer, if it's legal (but probably more importantly, a good idea) to wear flip flops to fly a plane? I'm training in a 172, if that's an important factor.
There is no policy on the books that I can find in regards to this. Loosely if flip-flops make it hard for you to operate the rudder it would fall under the catch all:
(a)Aircraft operations for the purpose of air navigation. No person may operate an aircraft in a careless or reckless manner so as to endanger the life or property of another.
However I was at an FAA WINGS lecture not all to long ago on preparing for accidents. My local FSDO's advice was to "dress for the crash" i.e. if you plan to fly over snowy terrain consider wearing boots etc. With this in mind flip-flops are more than likely not a great choice. The need to walk considerable distances over terrain is not unheard of after an accident.
Flying in tropical areas (outside the US), I have frequently observed the locals going barefoot. There is no dress code in 14 CFR 61, 91.
Large boots can be problematic. I tend to wear sneakers, even when flying for work. I get better feel of the rudder pedals, and boots and dress shoes are hard for me to find, as I have very large feet, and they tend to have even larger "foot prints" because of the design of the footgear.
I can tell you that more than one student who showed up in pumps had problems with rudder and brake operation. Usually it only took one flight to convince them to bring slides or some other shoe.