South Korea’s leading low-cost carrier, heavy with debt and its stock already near record lows, is now facing intense public and government scrutiny.

Officials are inspecting the black boxes recovered from the wreckage of Jeju Air flight 7C2216 and have promised to release updates as soon as possible. The Boeing 737-800 is believed to have suffered a bird strike, but the exact circumstances surrounding its belly landing and subsequent destruction are unclear.

Belly-landings are risky and carried out only in an emergency. Here are the situations in which this is done, and what probably happened with the Jeju aircraft.