Media coverage of the Asiana 214 crash underscored a problem with accident reporting: the pilots who know the most about the accident aircraft are often
777 Cockpit. Image from Wikimedia Commons.
not the ones you see on television. That’s because most airline pilots are barred by union policy from commenting and sharing what they know. Retired airline pilots are free to comment, though I didn’t see any 777 pilots interviewed. So to get some insight into 777 procedures, I recently met up at a Starbucks with a retired 777 pilot.
As background, let me mention that NBC Bay Area invited me to watch the July 10 NTSB press conference in their studio and answer questions for their reporter. During that press conference, NTSB chairwoman Deborah Hersman included these observations of post-crash switch positions:
- The Flight Director was on for the right seat (instructor pilot), but off for the left seat (pilot flying)
- The autothrottles were armed. In response to a subsequent question, she stated that although armed, the autothrottles were not engaged.
Of course switch positions could have been changed after the crash and before the NTSB examined them. But chairwoman Hersman also stated that the instructor pilot said he assumed that the autothrottles were maintaining aircraft speed, meaning he thought they were engaged. Aircraft tracking data shows a decreasing groundspeed during the approach, suggesting the autothrottles were not engaged.
The retired 777 pilot I spoke with is not interested in being publically identified and I’ll alternate using he and she when describing this pilot’s comments to me.
He said that the only way a 777 gets slow is if the autothrottles are not engaged, even if they are armed. Yet she said that Boeing procedures are for the autothrottles to remain engaged throughout the landing until after the aircraft rolls out onto the runway. He also said that the crew would have had to turn off the autothrottles, as there is no autopilot mode that disengages them.
Some other airliners require that their autothrottles be disengaged before touchdown, but the 777 differs since its autothrottles include a gust inhibitor capability. Since it’s computer controlled, it responds to wind shifts more rapidly than a human could operate the throttles. Hence even when pilots hand fly a 777 to a landing and touchdown, the Boeing recommended procedure is to keep the autothrottles engaged.
The 777 pilot also said that having the flight director turned off goes against recommended procedures. For pilots unfamiliar with a flight director, the definition from the glossary of my Max Trescott’s G1000 Glass Cockpit Handbook is:
“Software which provides pitch and roll commands that are displayed on the PFD [Primary Flight Display]. You can either manually fly the airplane to follow the commands, or engage the autopilot and have it follow the commands for you.”
With the flight director on and properly configured, a pilot merely has to manipulate the controls to tuck the airplane symbol up tightly under the flight director’s command bars. Flying the airplane becomes as simple as playing a video game where you move the controls to follow a moving element on screen.
With a flight director turned off, a pilot flies with “raw data,” which means just the basic instrumentation you might see in a typical general aviation cockpit with round gauges. When flying a visual approach with raw data, the pilot would have to interpret multiple instruments to determine whether he or she is flying an appropriate visual glide path to the airport.
But the 777 is not typically flown with raw data. The pilot I spoke with said that her airline required that every visual approach be flown with the flight director engaged and configured to provide electronic guidance for the descent profile. Typically, this would be by coupling an ILS signal or other preprogrammed approach to the flight director. Thus as the pilot flew visually, he or she could periodically refer to just the flight director to determine whether he or she was tracking the desired descent profile.
But according to FAA NOTAMs, the ILS for runway 28L has been out of service at SFO since early June. In that case, the 777 pilot told me she would have used the 777’s avionics to create an artificial glide path simulating an ILS glideslope. It would guide the aircraft from a point 1,000 feet above the ground and three miles away from the runway along a glide path that would be 50 feet high as it crossed the runway threshold.
According to the NTSB, the accident flight crew called for a go around only a few seconds before impact. The 777 pilot I spoke with mentioned that not all 777 pilots are aware of one aspect of go around button usage. A single push of the go around button commands the throttles to “go around” power. However a second push of the button brings the throttles to “maximum continuous” power. No data has been released by the NTSB on the Asiana 214 crew’s use of the go around button.
The 777 pilot did comment that it was permissible to engage the autopilot after takeoff while climbing through 400 feet and to leave it on until the aircraft rolled out on the runway after landing. So conceivably during a 16-hour flight, a pilot might get only about 30 seconds of experience hand flying the aircraft!
The pilot I spoke with would typically hand fly the aircraft after takeoff up to the initial level off altitude, unless the cockpit became busy and safety dictated engaging the autopilot earlier. For landings, he would typically disengage the autopilot—not the autothrottles—near the outer marker and hand fly the aircraft for the last 1500 feet. The pilot did make a point to use the autoland capability at least once every three to six months to remain proficient in those procedures.
The 777 pilot also offered some comments on being a first officer, saying that it was the most difficult job, since it required adjusting to the styles of different captains. She mentioned that the relief pilot—the third pilot in the cockpit—had one of the best views, since from their vantage point, the relief pilot could see where the pilots’ eyes were looking and hence determine if something was being overlooked.
It will probably be a year before the NTSB releases a final report on the Asiana 214 crash. In many cases, the probable cause released in a final report is very different from what it appears to be immediately after an accident. So while many people have speculated that pilot error was involved in this crash, we should all await the final report before drawing any final conclusions.