This photo taken on February 14, 2017 shows an aerial view of the North Korean border city of Sinuiju and the Chinese city of Zhenxing separated by the Yalu river during an Air Koryo flight aboard a Tupolev Tu-204 aircraft en route to Pyongyang. Photo: AFP / Ed Jones

The vast majority of airlines currently avoid flying through North Korea’s flight information region or FIR in the wake of Pyongyang’s missile launches.

The carriers are reacting to safety concerns now that the pilots of several commercial flights have observed the fiery re-entry of North Korean missile tests from their planes — though the odds of being hit by such projectiles are very low.

Flying through the North’s FIR is geographically the shortest distance for aircraft flying between the US and South Korea. Abandoning the route has reportedly increased flight times by 30 to 40 minutes, eating up more fuel and increasing carrier costs by billions.

South Korean newspaper Chosun Ilbo reports that only a few Russian carriers are still using the FIR, which is a specified region of airspace in which a flight information service and alerts are provided by the airlines to appropriate nations.

North Korea used to inform the overseeing International Civil Aviation Organization of impending missile launches until February 2016. But it has stopped making notifications since then.

The South’s Ministry of Land, Infrastructure and Transport reportedly said that airlines from 17 countries flew through Pyongyang’s FIR on flights to South Korea in 2015. But as of last month, only seven Russian carriers were still using the route. The number of airlines using the FIR has steadily dropped in the last two years.

North Korea tested a Hwasong-15 intercontinental ballistic missile on November 29. It’s re-entry was viewed from a distance by a Cathay Pacific pilot from the cockpit of his plane.