Did the Asiana Crew Fail to Monitor Air Speed?

Within hours of the crash landing of Asiana flight OZ214 at San Francisco’s airport, National Transportation and Safety Board (NTSB) chairman Deborah Hersman was on the scene. Over the next five days she gave daily briefings to the media on how her agency’s investigation was proceeding and what they had found. She was remarkably consistent in sticking to what she referred to as the “factual information” her team had gathered and she steadfastly refused to speculate on what factors might have been responsible for the accident.

During the question and answer period that followed her first briefing on July 7, she was asked if they had found any pilot error. “What I will tell you is the NTSB conducts very thorough investigations,” she said. “We will not reach a determination of probable cause in the first few days that we’re on an accident scene.” When asked to give her opinion on a possible cause of the crash, she often simply repeated known facts that had been uncovered – the aircraft’s speed and altitude at a given time, or what had been mentioned on the cockpit voice recorder.

Hersman’s no-speculation policy was so consistent that the few times she offered a viewpoint that could be considered even slightly evaluative, her words took on extra weight, as if to say, “Pay attention. This is an important point.” Indeed, the first time this happened, at the end of the third briefing, during the question and answer period, Hersman herself added the emphasis. “But let me be very clear,” she said. “The crew is required to maintain a safe aircraft. That means the need to monitor. We have a flying pilot, we have two other pilots that are in the cockpit and they have a monitoring function. One of the very critical things that need to be monitored on an approach to landing is speed. So we need to understand what was going on in the cockpit and with the aircraft.”

Hersman repeated this point several times during the fourth briefing. “You have two pilots for a reason,” she said. “One of the pilots is charged with monitoring. In fact duties are broken up. One pilot is the designated flyer and one is designated to monitor.” Later she stated, “And so we have a pilot in command who is the monitoring pilot. It is his responsibility to make sure that this is a safe flight as the pilot in command.”

All of this takes on critical importance because the aircraft had slowed to 103 knots (119 miles per hour) just before it crashed, significantly below the 137 knots (approximately 158 miles per hour) the pilots thought they were maintaining – the speed to which the auto throttle had been set. There is some question as to whether the auto throttle was actually engaged during the final few minutes of the flight (although the latest information is that it was armed, but there is still some question about what mode it was in), but there is no question that the aircraft was flying much too slowly (dangerously close to stalling), and no one appeared to notice until it was too late.

The question is, why? An NBC news report today from Associated Press reporter Joan Lowy offers one possible explanation.

Simply put, it comes down to an obvious human characteristic. If a system hardly ever fails, we are not likely to pay close attention to it. And the automated systems in airplanes, like the auto throttle at the center of the Asiana crash, rarely fail. A pilot might believe it to be in one mode when, in fact, it is in a different one. What does the system do to advise both pilots as to the mode it actually is in? What do they have to look at to verify its mode?

According to Lowy’s report, the failure to monitor automation has been a factor in several previous crashes, and well before the flight of Asiana OZ214, the NTSB had recommended that the Federal Aviation Administration “require that pilot training programs be modified to contain segments that teach and emphasize monitoring skills and how to manage multiple tasks. An NTSB board member quoted in Lowy’s story characterized the FAA’s response to that recommendation as “unsatisfactory.”

At this point the role that the Asiana aircraft’s auto throttle – and its monitoring by the pilots – played in the accident, is still unknown. But the crash of Asiana flight OZ214 may well end up adding renewed urgency to the NTSB’s request.

By Ronald L. M. Goldman Google+

By | 2016-10-17T11:52:57+00:00 July 18th, 2013|Aviation News, Ronald L. M. Goldman|