53 mhz
It is my opinion that the 50/53 bands are now too dirty to be safe for flying.
On a daily basis I watch ground noise with my spectrum analyzer. The noise is so much higher than in the 72 band, with lots of mysterious clutter and intermittent carriers. High tension power lines and radio transmission repeaters constantly produce harmonic noise on 53 esp.
I would not fly on 50/53. Too much money in the air to mess with something so unreliable.