Abstract: In order to study the inherent law of the development of aircraft cargo compartment fire to flashover in a low-pressure environment, a series of fire flashover experiments were carried out using a 1/4-volume standard aircraft cargo compartment at an altitude of 4 260 m and an air pressure of 60 kPa. Jet fuel was selected as the main fuel, and the ignition of single-walled corrugated boxes were used as the criterion for flashover. The effects of different fire source sizes on flashover at low pressure were studied. Through the measurement and analysis of the average temperature of the hot smoke layer in the cargo compartment, the radiant heat flux on the floor, the fuel heat release rate and the smoke volume fraction, the critical conditions and manifestations of flashover under at pressure were discussed. The results show that the increase in the size of the fire source increases the possibility of flashover and the severity of flashover. After reaching the critical fire source size required for flashover, continuing to increase the fire source size will advance the timing of flashover. The critical conditions for flashover of the aircraft cargo compartment under a pressure of 60 kPa are: the average temperature of the upper hot smoke layer reaches 553.5 ℃, and the radiant heat flux received by the floor reaches 19.85 kW/m2.

Key words: low air pressure, aircraft cargo compartment, flashover, average temperature of the hot smoke layer, radiant heat flux on the floor, critical conditions