It appeared at first that an onboard fire had led to the emergency landing at New Orleans, on April 4, of United Airlines’ Flight 497, an Airbus A-320, but investigators announced Thursday they had no evidence to support that. According to the NTSB, shortly after takeoff an automated system warned the crew of smoke in the equipment bay. But “preliminary examination has not revealed any signs of burning, indications of smoke or other anomalous system findings,” according to the NTSB. Plus, the agency says neither the captain or copilot recalled smelling smoke or fumes during the flight and pre-interview reports suggest the cabin crew didn’t smell or see smoke, either. What we know is that the aircraft had issued an autothrottle-related message, followed by the avionics smoke warning, which included instructions to land. The captain says he followed the relevant checklist, which led him to shut down some of the aircraft’s electrical systems. And then things got more interesting.
After following the checklist, the first officer’s displays were blank, the automated messages disappeared, the cockpit-to-cabin intercom didn’t work and the air-driven emergency generator deployed. The captain took control of the aircraft and turned back for New Orleans, requesting Runway 10/28, the airport’s longest runway. Controllers told the crew the runway was unavailable due to the presence of maintenance vehicles. The flight ultimately landed on Runway 19, from which it had departed 12 minutes earlier, but not before the crew’s declaration that “we’ve lost all our instruments.” The aircraft landed safely, but the nosewheel departed the left side of the runway. Passengers were evacuated via the aircraft’s slides. The NTSB will be conducting formal interviews of cabin crew, poring over cockpit voice recordings and sifting through more than 25 hours of information from the aircraft’s flight data recorder.