Air France Flight 4590 crash and possible remedies. Air France's Concorde operation had been a money-losing venture, but it is claimed that the aeroplane had been kept in service as a matter of national pride; British Airways claimed to make a profit on its Concorde operations. According to Jock Lowe, a Concorde pilot, up until the crash of Air France Flight 4590 at Paris, the British Airways Concorde operation made a net average profit of about £30m a year. Commercial service was resumed in November 2001 after a £17m safety improvement service, until the remaining aircraft were retired in 2003. The official investigation was
Concorde quoted as saying, "It is certain on present evidence and calculations that in the airport context, production Concordes will be no worse than aircraft now in service and will in fact be better than many of them." Concorde produced nitrogen oxides in its exhaust, which, despite complicated interactions with other ozone-depleting chemicals, are understood to result in degradation to the ozone layer at the stratospheric altitudes it cruised. It has been pointed out that other, lower-flying, airliners produce ozone during their flights in the troposphere, but vertical transit of gases between the layers is restricted. The small fleet meant overall