Are there good exercises to do to prevent dvt and pe on long flights?

Move feet, walk: If in economy seats: 1) flex, extend, & evert to both sides your feet several times every hour. Bend each foot at the ankle down, then up, then to the left & right. This will get the circulation moving in the legs. If in a premium seat, stretch your legs and flex/extend at the knee to move blood in the thigh & knee. 2) if permitted, walk around the cabin too.

Use resistance: The exercises that dr. Bansal recommended are excellent. They work even better if you can do any of them against resistance. Use the support framework of the seat in front of you to push against and you will make your much more effective as a preventative exercise. Walking is great, if possible, and stay well hyhdrated.

Foot pump: Trying to keep the venous blood flowing in your legs is a way to reduce possibility of a dvt. Regularly moving your foot up and down, flexing and extending your knee, and regularly getting up and walking around can help from a mechanical Perspective. It you take an NSAIDs, such as ibuprofen or alleve for example, this inhibits platelette function reducing blood clot risk as well.