Political reasons

The Chinese government has placed restrictions on flights over certain areas of Tibet, citing national security concerns. Tibet is a politically sensitive region, and the Chinese government has sought to maintain control over the region and limit foreign influence. As part of this effort, the Chinese government has placed restrictions on who can travel to and within Tibet, as well as on which areas planes can fly over.

In some cases, the Chinese government has prohibited flights over certain areas of Tibet altogether, particularly those near the borders with India and Nepal. This is because these areas are considered to be sensitive from a national security perspective, and the Chinese government wants to limit foreign surveillance of the region.

In addition, the Chinese government has also placed restrictions on the types of planes that can fly over Tibet. These political restrictions create additional challenges for airlines that want to fly over Tibet, as they must navigate a complex web of regulations and restrictions. As a result, many airlines choose to avoid flying over the region altogether or limit their flights to certain times of the year when the risks are lower.