Hi, I am ET (+CARL). I am in Vietnam and fly at least once a year to visit my mother (luckily, my flights are only over 2 hours). As I understand it, high platelets can increase the risk of blood clots. During long flights, this risk can increase due to decreased blood flow and increased blood viscosity.
So during the flight, my MPN doctor advised me to get up and move around at least every 1 hour to increase blood flow. Drink enough water to help maintain blood viscosity and reduce the risk of blood clots.
In case of long flights, I think you should consult your doctor. They can provide specific instructions on how to manage your condition during the trip and can consider necessary precautions based on your health status.

Hi - my platelets usually average 800, have gone over 900 before, I’m on aspirin only and I have flown long-haul quite a bit during this time. There are a few Q&A threads on here about flying if you want to look at more responses, a number of us on here fly and just take precautions depending on our situations, and our MPN specialists haven’t recommended otherwise. I make to sure to have enough leg room, stretch, stand/move around if needed, not wear tighter clothing etc as a precaution. Granted everyone might be different in terms of their situation, so as Tina said would be good for you to know the background behind your Drs concerns.

Thanks!! :-)