The deadliest accident in aviation history occurred in 1977, when two Boeing 747 jumbo jets collided on a foggy runway on the Spanish island of Tenerife, killing 583 of the 644 people on board the planes. Spanish investigators blamed the captain of the KLM 747 for taking off without clearance from air traffic controllers.

An air safety expert says lives could have been saved if the "obstruction" was not there.

Accident investigators are trying to find the cause of a Jeju Air fatal crash landing that killed 179 of the 181 on board the flight.