I am looking to fly from Kathmandu to Beijing in April, however the only route with Air China is the following:

Flight 1: Air China Flight CA408 from Kathmandu, Nepal to Chengdu,China (including 1 transit stop) [Departure 10:35,Arrival 16:45]

Flight 2: Air China Flight CA4111 from Chengdu, China to Beijing, China [Departure 19:00, Arrival 21:30]

Through looking at the flights in more detail. Flight 1 makes a one hour transit stop in Lhasa, Tibet. I am not interested in deplaning in Tibet, but I am concerned that additional permits may be required in reaching my final destination, Beijing.

Are any permits required if a flight from Kathmandu to Chengdu transits via Lhasa?

Thank you,
Daniel.