Major airlines have stopped using Afghan airspace as Islamist group the Taliban moved to seize control of the capital of Kabul.
United Airlines, British Airways and Virgin Atlantic have all said they are re-routing flights, with the US-India flight path particularly affected.
Many aircraft are now flying over Pakistan and Iran instead.
Airlines and governments are more concerned about carriers flying over conflict zones after two deadly incidents involving surface-to-air missiles in Ukraine and Iran.
Commercial flights to Kabul have also been affected. Emirates is among airlines to have suspended all flights to the Afghan capital until further notice.
Meanwhile, US troops were reportedly forced to fire warning shots into the air amid chaotic scenes at Kabul airport to prevent crowds of citizens running onto aircraft.
An official was quoted by Reuters as saying: “The crowd was out of control. The firing was only done to defuse the chaos.”
Gunfire could be heard in several videos on social media. The desperate scenes include crowds hovering around aircraft and clambering up staircases.
US troops are in charge at the airport, where they are reportedly prioritising the evacuation of embassy staff on military flights.
More than 60 countries, including the UK and US, issued a joint statement calling on the Taliban to allow people to leave