After femoral artery leg bypass surgery, how long before you can fly on a plane?

Depends, of course: Open bypass surgery usually requires 2-3 days in the hospital to regain adequate activity to go home, then again a slow return to regular activity in 2-4 weeks. Air travel should be ok within 2 weeks after surgery, depending on one's activity level.

Soon: Preferably when pain, and swelling are gone. Sitting scrunched up is not ideal . Remember to walk about and stretch and flex and extend. If you we're given support stockings you may wish to use.