The official test may overestimate the efficiency of an evacuation because there's no real urgency among the passengers. (It's easier to orchestrate an orderly evacuation if no one really thinks they're going to die.) The test conditions also fail to capture some of the most dangerous elements of a real evacuation, like smoke. A British government report on a real cabin fire from 1985 illustrates the point: "After the aircraft stopped, the aft cabin was suddenly filled with thick black smoke which induced panic. … Many passengers stumbled and collapsed in the aisle, forcing others to go over the seat-backs." The long-standing 90-second rule provides another easy target for criticism: It may not apply to the newer planes with extra-large cabins.