In over 40 years of aviation photography I've never used a tripod except for the odd static night shot and, at one month short of 69, can't see why one would be advantageous.
Tripods ( or at a push a monopod ) are very useful for unique dawn and dusk shots , particularly of daytime-shy types. I was photographing freighters the other morning around 05:00 and needed 1/160 to 1/250 shutter with ISO1600. No way you can hand-hold that on a long-lens.
And they're also great for catching helicopters, you'll need similarly slow shutter speeds to blur the rotors.
If you just want run-of-the-mill daytime shots of the same airliners that everyone already photographs then you'll probably be fine without one. In which case why bother? Is it worth the investment? You'll be 'competing' againt rich amateurs with £8k+ of kit, might be better to sit and browse their output on jetphotos.net or hire kit for a week from
Lenses for Hire.