Today marks the 16th anniversary of the Space Shuttle Columbia’s disaster.
On 1 February 2003, Columbia disintegrated upon re-entering the Earth’s atmosphere killing all seven crew members only minutes before it was scheduled to land at the Kennedy Space Center. The disaster was the second fatal accident in the Space Shuttle program after the Space Shuttle Challenger broke apart 73 seconds after lift-off in 1986, killing all seven crew members.
During the launch of Columbia’s 28th space mission, a piece of foam insulation broke off from an external fuel tank and struck the left wing of the orbiter. Similar incidents had occurred on three earlier shuttle launches without causing critical damage, so while some engineers at the space agency believed the damage to the wing could be disastrous, their concerns were not addressed during the two weeks Columbia spent in orbit.
When Columbia re-entered the Earth’s atmosphere the damage allowed hot atmospheric gases to penetrate the heat shield and destroy the internal wing structure, which caused the spacecraft to become unstable and break apart.
Foam loss from an external fuel tank of a shuttle was a known problem to NASA but the lack of negative consequences occurring during the previous 22 years of shuttle flight had led to an acceptance of damaged heat shields as part of the norm of missions. Foam loss was viewed as a maintenance issue rather than a safety-of-flight issue. Ironically, the foam was in place around the very cold liquid fuel in the tank to prevent ice formation, which could damage the orbiter if it dislodged during launch.
Diane Vaughan, an American sociologist who has spent her career studying organisations where deviations from rules and practices becomes the norm—often with devasting consequences–coined the term ‘normalisation of deviance’. She defines the term as ‘the gradual process through which unacceptable practice or standards become acceptable and as the deviant behaviour is repeated without catastrophic results, it becomes the social norm for the organisation’. Vaughan coined the term in her analysis of the previous space shuttle disaster in her book, The Challenger Launch Decision. Normalisation of deviance should be of concern to anyone in aviation, be they an astronaut, engineer, air traffic controller or pilot of any type of aircraft.
Flight Safety Australia looked at this issue in Safety in mind: normalisation of deviance in May 2017.