American Airlines accidentally flew an unauthorized plane from Los Angeles to Hawaii last month.
The mistake, which was first reported by an aviation blogger and later confirmed by CNN, violated Federal Aviation Administration regulations, since the Airbus A321S aircraft did not have the required Extended Operations certification to travel long distances over water.
The certification requires that planes that fly long routes with no alternative landing locations carry extra oxygen and an extra fire suppression canister, the Washington Post reports.
The Aug. 31 flight, AA Flight 31, arrived safely in Honolulu, but an American Airlines spokesperson told CNN that "someone on the ground" noticed the mistake half-way through the flight and immediately notified the FAA and flight crew.
Officials made the decision for the A321S to continue its flight to Honolulu, but its return flight was canceled and the plane was sent back to Los Angeles with minimal crew.
The plane that should have flown to Hawaii -- an A321H -- is the same plane as the one that completed AA Flight 31, the AA spokesperson told the Agence France-Press, but it would have had the additional equipment required by the Extended Operations certification.
Brian Sumers, the aviation expert who first spotted the mix-up, wrote on his blog that the mistake "wasn't necessarily unsafe -- both versions of the A321s are essentially the same aircraft and each has emergency life rafts required for a water evacuation -- but this is a major violation of federal guidelines."
American Airlines says it has since upgraded its software so that its planes operate on the correct routes.
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