The decision by several airlines to avoid the airspace over the Sinai Peninsula following the break-up of a Russian passenger jet was only the latest addition to a list of official and self-selected no-go zones.
Investigators have not yet said what caused the plane to break up midair, and analysts say a missile attack was unlikely. But an Isis-linked group's claim that it brought down the plane has raised concerns among pilots and operators.
"The long-term impact may be that flights in the area will take longer," said Ian Petchenik, who works for the airspace tracking website Flightradar24. He was referring to the decision by several airlines, including Lufthansa, Air France, Emirates, Air Arabia and Flydubai, to divert their planes. "However, there is no dramatic change in terms of volume of flights.
"The crash on the Sinai Peninsula took place in an area few aircraft are transiting. It's not like in Ukraine or Iraq where hundreds of planes had to be diverted," Petchenik said, mentioning two countries where fighting has forced airlines to divert flights.