Is 2 weeks too soon to do air travel after major surgery. going on a 3 hour flight. ?

Depends: It really depends upon the surgery and your overall health condition. You need to check with your surgeon and follow their advice. If they say no please do not try it. Many things can happen after a surgery and you do not want to have a complication while on a plane.

Flying post surgery: Flying after surgery depends on what kind of surgery one has had, were there any complications , what other medical problems person has , what is their risk of having a clot in leg . Every airline has its own regulations about flying after surgery . It is best to check with surgeon and if possible to discuss with Gp or a travel doctor and check with respective airlines too.

Travel after surgery: It should be fine travel after 2 weeks of a major surgery . 3 hour flight is a short flight. Usually 10 days is good enough after a complicated abdominal surg, chest surgery or a CABG

Likely not an issue: It would depend on the type and duration of surgery, any other medical issues, and how you felt. Worth discussing with both the surgeon and the anesthesiologist prior to surgery and in the recovery room.