JT just scored his 737 license ... and he was pleased to crow about it to his 3.8 million followers, saying, “Okay, so a very proud moment in my aviation history.”

He went on -- and this is interesting -- “To add to my 747 and 707 licenses, I just received my 737 (pilot) license, and it went very well.” It's interesting he chose to go for a jumbo jet -- the 747 -- and a 4 engine passenger jet -- the 707 -- before getting certified on the smaller, 2-engine 737.

The 68-year-old actor has a fleet of planes, including a Bombardier Challenger 601, a Boeing 707-138B, and an Eclipse 500.

He bought the 707 22 years ago for $77 million, tricking it out inside for another $20M.

It's pretty amazing ... the jet can seat 150 passengers, but Travolta reconfigured it so it carries 15 passengers in high style. It has 2 bedrooms and an impressive bathroom and shower.

John lives in a private aviation community in Florida that has a full-sized runway. He parks his jets the same we we park our cars.

John's been flying since he was 15 and got his first license back in 1978.