Pressure mounts on Boeing to change widebody safety system

[smhusain_1]

"Boeing and the FAA are facing increasing pressure to change speed controls, training and warning systems for the 777 in the wake of the Asiana Airlines Flight 214 accident in San Francisco. National Transportation Safety Board (NTSB), in its final meeting on the July 6, 2013, accident, called on the FAA to launch a special certification review to analyse how the 777 automatic flight control system (AFCS) regulates airspeed, elements the Board said contributed to a poorly executed visual, hand-flown approach that resulted in the aircraft flying too slowly with its engines idled.
3 passengers were killed and 187 injured when the Boeing 777-200ER struck the sea wall ahead of runway 28L, although investigators asserted that two of the three deaths could likely have been prevented had the passengers been wearing seat belts.

Along with the special certification review (SCR) recommendation, the NTSB also asked the FAA to change 777 training curriculum and aircraft documentation to aid pilot understanding of autothrottle modes, including automatic activation modes, and to enlist a panel of experts to develop a context-dependent low energy alerting system. The NTSB is also suggesting that Boeing amend the 777 AFCS design based on input from the new panel, and insert more information about autothrottle subtleties in its 77 flight-crew operations manual. The safety board issued four training-related recommendations to Asiana; the carrier says it has already complied. Six more recommendations, four geared toward an airport rescue and fire-fighter advocacy group and two to the airport’s operators were based on their respective emergency responses to the crash.

The NTSB laid the blame for the Asiana accident squarely on the pilots, who mismanaged the airplane’s descent, inadequately monitored aircraft performance, did not follow Asiana standard operating procedures, and delayed a go-around decision until too late despite being aware that the aircraft was below acceptable glidepath and airspeed tolerances earlier in the approach. Both Boeing and Asiana agree that pilot error was the primary cause. Also included in the probable cause, however, was the pilot-flying’s unintended deactivation of the 777’s automatic airspeed control, an action investigators linked in part to his confusion about the operation of Boeing’s Flight level Change (FLCH) vertical control mode in the AFCS.

Mode confusion topped the list of five contributing factors. Also cited were the complexities of the autothrottle and autopilot flight-director systems that were inadequately described in Boeing’s documentation and Asiana’s pilot training which increased the likeliness of mode error.
The mode error occurred when the pilot-flying selected FLCH on the mode control panel at 1,600 feet altitude, 3.4 nm from landing when the Aircraft was high and fast compared to the desired glidepath. The 777 autopilot responded by increasing thrust and raising the nose-to-climb to 3000 feet, the go- around altitude the crew had previously entered into the system. Because the pilot was looking for the opposite effect, he turned off the autopilot, and reduced thrust to idle. That action when in FLCH causes the autothrottles to enter a hold mode that does not control airspeed. In that situation Asiana procedures call for the pilots to switch off both flight directors, an action that resets the autothrottles to speed mode and would have maintained the pre-set speed of 137 kt. Data shows that both flight directors were not switched off simultaneously, despite the pilot-flying recollection of doing so. The hold mode also does not include low-speed protection which in most other modes automatically adds power when airspeeds dip below minimum manoeuvring speed. The expectation was that the autothrottle was going to take of the airspeed, says NTSB member Robert Sumwalt, a former Airbus pilot for US Airways. Nowhere in the documentation is it clear. It is in there, if you put two and two and 16 together and divide by three, and then multiply by something else. If you piece it all together you can understand this bit, it wasn’t clearly presented to this pilot.

With the autothrottles at idle, the aircraft descended below the glideslope, despite the pilot attempting to climb and the airspeed dropping. At 11 sec before impact, the 777’s low speed master caution alert sounded and 4 sec later, the pilot-monitoring advanced the thrust levers and issued a verbal call for a go- around. The actions were too late as main gear and underside of the aft fuselage struck the sea wall, states the NTSB. Investigators determined that if the autothrottle had been equipped with the automatic wake-up function, it would likely have activated and increased power about 20 sec before impact, which may have prevented the accident.

Boeing says all its 777 systems performed on Asiana 214 and that it respectfully disagrees with the NTSB assertion that the 777 autofllght system contributed to the accident, a finding we do not believe is supported by the evidence. We note that the 777 has an extraordinary record of safety, a record established over decades of safe operation, the company said in a statement following the NTSB’s recommendations. More specifically, the auto-flight system has been used successfully for over 200 million flight hours across several airplane models, and for more than 55 million landings.
Based on the aircraft’s history and sparse documented reports on FLCH problems, NTSB members were split on the recommendation for the two voted for keeping the language in the final report, two wanted it removed. Earlier in the investigation, details emerged that the FAA and European Aviation Safety Agency (EASA) had pressured Boeing to make changes to the AFCS for the 787, which mirrors the 777 system. According to a 2011 report from 787 certification testing, the FAA strongly encouraged, Boeing to provide autothrottle wake up capability in all autothrottle modes after an FAA pilot noted the lack of wake-up capability in the FLCH mode."

Excerpts: Change Agent by John Croft AWST June 30, 2014, Washington D.C.

[TAILWIND]

IMO Boeing and Airbus are un-neccesarily increasing automation to the extent that this itself has become a hazard. Pilots are unable to select right amount automation for the circumstances and end up in trouble. There was a good presentation on automation dependency http://www.youtube.com/watch?v=R0rYX-Jn6o8.

[smhusain_1]

You should try and find out from our pilots flying the 777 whether improvements are due in the Auto Flight Control System (AFCS). The scenario in the crash of Asiana 214 and the selections made in the above system would best be answered by them and would be of great interest to all of us. NTSB as you know has listed the interface between the pilot and system as a contributing factor although they haven't said here was any fault but was used incorrectly.