Hello Joanna2007, thank you for your reply!
I actually don't take them on a regular basis but about the tolerance, I take pills almost everytime I feel kinda sick (if I feel tingly in the throat, I take antibiotics with analgesics, if I get a big headache, I take 1gr of Panadol) so I don't know about the tolerance for a benzo like xanax.
I will follow your advice on taking 1mg an hour before take-off and then .5mg every 2-3 hours. My MD is on holidays now (Hawaii) and it is hard to contact him.
Thank you for your response and advice!