Not going to win, but the Lhasa Gonggar Airport (LXA) is 97km away from downtown Lhasa. Nevertheless, it is going to win in one aspect: it is the only civilian airport serving Lhasa, making Lhasa the most distant city to any airport among all the cities that have been mentioned. A new airport is under construction in Lhasa to allow better access to the city center...and the new airport is 70 km away from downtown Lhasa. The main problem is that Tibet is too mountainous and it is hard to find a large enough expanse of flat land suitable for an airport.

Not going to win, but the Lhasa Gonggar Airport (LXA) is 97km away from downtown Lhasa. Nevertheless, it is going to win in one aspect: it is the only civilian airport serving Lhasa, making Lhasa the most distant city to any airport among all the cities that have been mentioned. 

A new airport is under construction in Lhasa to allow easier access to the city center...and the new airport is 70 km away from downtown Lhasa. The main problem here is that Tibet is too mountainous and it is hard to find a large enough expanse of flat land suitable for an airport.