July 15, 2013
Complications and distractions aside, over-reliance on automation systems appears to have trumped basic flying skills and crew resource management in the crash of Asiana Airlines Flight 214 at San Francisco International Airport on July 6.
The accident will put additional pressure on an industry already grappling with implementing training and human-factors lessons learned from recent high-profile pilot-error-related accidents such as the 2009 Colgan Air Q400 loss-of-control crash in Buffalo, N.Y., and the Air France A330 accident off the coast of Brazil. In response to the Colgan accident, the FAA will soon publish a final rule requiring first-officer hires to have at least 1,500 hr. of flight time and an air transport pilot certificate and type rating, a six-fold increase compared to the 250 hr. and commercial pilot certificate minimums today.
Meanwhile, avionics manufacturers are making headway on research to simplify the complex and often confusing human-machine interfaces that hinder rather than help pilots. Rockwell Collins is working on a project to reduce the number of federated automatic flight control (auto-flight) modes added to the flight deck. By aligning auto-flight modes with pilot “goals”—arriving at a certain point at a certain time with a given amount of fuel—researchers were able to design a prototype mode manager that effectively gives pilots seven auto-flight mode choices rather than as many as 38.
Adding to the confusion are multiple modes for autothrottle systems that link to complex auto-flight and autopilot systems. Autothrottles provide automatic speed or vertical speed control, including stall prevention in some modes, allowing pilots to focus on other tasks. According to Boeing documentation, the 777's autopilot has five operating modes.
Mode confusion could have played a role in the Asiana crash—the pilot-in-command of the highly automated 777-200ER expected that the Boeing's autothrottle system would hold the aircraft's approach speed to a preset value of 137 kt. as the aircraft, high on the initial approach, descended to capture a visual or electronic glideslope.
The system did not maintain the speed, leaving the engines at flight idle through the final portions of the approach and placing the aircraft very near an aerodynamic stall less than 200 ft. above San Francisco Bay in a high-drag state with landing gear and flaps deployed to 30 deg. before pilots detected the error.
The crew attempted a full-thrust go-around, but the call came too late, as the twinjet's main landing gear and tail clipped a seawall ahead of Runway 28L 1.5 sec. later. The impact removed the landing gear and the empennage, leaving everything forward of the aft pressure bulkhead to skid and spin uncontrolled on its belly down the runway. Despite the violent conclusion, the airframe and cabin largely held together, allowing 123 of the 307 passengers and crew on board to walk away unassisted (see article below).