Question: How long will emergency battery power on a 757 energize the hot battery bus, the battery bus, the AC standby bus, and the DC standby bus?
Book Answer: 30 Minutes.
Field Test: One hour, forty minutes.
The 185 passengers on an American Airlines 757 en route from Seattle to New York had no way of knowing the serious trouble their jet was in last month when the pilots switched to backup battery power because of a problem that occurred soon after takeoff.
Those batteries supply power to the plane for only about 30 minutes. But nearly two hours later, with the jet in cruise flight over Michigan, the electrical systems in the cockpit and, then, the cabin began to fail because the batteries were drained.
Without power, the plane’s intercom went out and a flight attendant had to pass a note under the cockpit door to communicate with the crew.
As Flight 268 made an emergency landing at Chicago’s O’Hare International Airport, vital systems to control the jet were not working, including some wing flaps. When the jet touched down, the engine thrust reversers did not work to slow the Boeing 757-200 and it barreled down the runway, leaving a long trail of skid marks as the pilot pushed hard on the brakes to try to stop.
The jet did stop, finally, with all three main landing gear intentionally off the side of the pavement in the grass and the nose of the plane only 100 feet from the end of the blast pad pavement, which extends some 397 feet past the departure end of the runway.
Test pilots, gee. Aren’t they swell?