The Middle East is a key air corridor for planes heading to India, South-East Asia and Australia with 1,400 daily flights to and from Europe.
A safety debate about flying over the region is playing out in Europe because pilots there are protected by unions, unlike other parts of the world.
Reuters reviewed nine unpublished letters from four European unions representing pilots and crews that expressed worries about air safety over Middle Eastern countries.
The letters were sent to Wizz Air, Ryanair, airBaltic, the European Commission and the European Union Aviation Safety Agency (EASA) between June and August. Staff called on airlines to be more transparent about their decisions on routes and demanded the right to refuse to fly a dangerous route.
Some European airlines including Lufthansa and KLM allow crew to opt-out of routes they don’t feel are safe, but others such as Wizz Air, Ryanair and airBaltic don’t.
Air France opened an internal investigation after flight AF662 flew over Iraq on Oct. 1 during Tehran’s missile attack on Israel.