The Federal Aviation Administration (FAA) prohibits US aircraft from flying over several countries or specific areas in countries, including Iraq, Libya, North Korea, Somalia and Syria. After Flight MH17 was shot down over eastern Ukraine last year, the FAA added eastern Ukraine to its list. Ethiopia was recently removed from it.
Even before the break-up of the Russian aircraft over the Sinai Peninsula, the FAA had classified the region as "potentially hostile". Flying over the area was not prohibited, but the FAA stated that "all US air carriers and commercial operators ... (must) exercise extreme caution during flight operations due to ongoing violence, unrest, security operations and the risk to safety from small-arms, rocket-propelled grenades, mortars, anti-aircraft fire and shoulder-fired, manportable air defence systems".
According to Flightradar24, which tracks flights in real-time on its website, there were no commercial planes in the air over Northern Sinai as of Tuesday.
Only a few routes in the Middle East and North Africa are not affected by warnings or strict prohibitions. Planes flying from Europe to Asia or the other way have a limited number of options: They can fly over Egypt and then continue their journey via Saudi Arabia. Alternatively, many airlines opt for the shorter Caspian Sea route.
Concerns have been raised about the latter route: When Russia started bombing targets in Syria at the end of October, it did so from 1600km away. Russia's cruise missiles were launched from naval vessels stationed in the Caspian Sea. On their lethal mission, they crossed an area that is frequently used by commercial airlines.
Subsequently, flights over that particular South Caspian/Iran area decreased significantly between the middle of September and October 18.
But most airlines have resumed their regular routes in that area.