Boeing on Sunday said it conducted an informational session Saturday in Renton to share details with airlines as well as safety regulators about “our plan for supporting the safe return of the 737 MAX to commercial service.”
The jetmaker said it also has invited more than 200 airline pilots, technical leaders and regulators for the next session in Renton this Wednesday.
“We … plan to reach all current and many future MAX operators and their home regulators,” Boeing said.
In a separate statement, John Hamilton, chief engineer of Boeing Commercial Airplanes, defended the company against suggestions in the press that additional cockpit display features that are optional and sold separately to airlines should have been standard and might have helped prevent the two recent fatal crashes.
Hamilton is leading Boeing’s response to the deadly accidents, which appear to have been at least partly caused by flaws in the design of a new flight control system introduced on the MAX.
The informational sessions in Renton must be seen as an initial step in Boeing’s efforts to get the MAX back in the air.
For the grounding of the MAX to be lifted, a process likely to take months, investigators will first have to firmly establish the cause of the crashes, Boeing will have to produce a fix for any design flaws, and air safety regulators around the world will have to approve the fix.
In addition, Boeing will have to provide additional training to pilots on the suspect flight control system, which pilots were unaware of before the first crash of a Lion Air 737 MAX in Indonesia last October.
The separate statement by Hamilton on the pilot cockpit displays is a public relations defense against recent criticism.
The flight control system that appears to have repeatedly forced down the nose of the Lion Air jet before it finally crashed — and is suspected of playing a role in the crash of the Ethiopian Airlines jet this month — was triggered by a faulty signal from a single sensor that measured the plane’s angle of attack, the angle between the wing and the oncoming air flow.
Critics have noted that neither the Lion Air nor the Ethiopian Airlines pilots had any indicators on their cockpit displays to tell them the readings from the jet’s two angle of attack sensors.
Boeing does offer, for an extra price, two separate optional display features that would have addressed this. One is a light that illuminates when the signals from the plane’s two angle of attack sensors disagree. Another would provide the angle of attack data to the flight crew directly on the primary flight display.
But neither Lion Air nor Ethiopian had bought these extra features.
Hamilton defended the optional nature of those features by insisting that “all primary flight information required to safely and efficiently operate the 737 MAX is included on the baseline primary flight display.”
That is, the baseline, non-optional displays are all that are needed for safe operation of the MAX.
“There are no pilot actions or procedures during flight which require knowledge of angle of attack,” Hamilton added.
Boeing has contended since the crash that the pilots didn’t need to know what was causing the horizontal tail to swivel and push the nose down; they needed only to know that to handle any uncommanded movement of the horizontal tail — whatever the cause — they must follow a standard procedure that throws two cut-off switches to end the movement.
A light telling the Lion Air pilots that the angle of attack sensors were disagreeing, or better still a reading in the main display telling them that the two sensors differed in their measurement of the angle by a big margin of about 20 degrees, might have given them an extra clue as to what was happening.
However, since the pilots were entirely unaware of the existence of the new flight control system that the faulty angle of attack sensor activated, it’s questionable if it would have made a major difference in the crashes.
Hamilton said these features would only provide “supplementary information” to the flight crew and “additional context” for understanding what was going wrong with their airspeed and altitude readings, both of which use the angle of attack.
He said Boeing developed crew procedures and training “focused around airplane roll and pitch attitude, altitude, heading and vertical speed, all of which are integrated on the primary flight display,” and did not cite the angle of attack because this was peripheral to those main data points.
Nevertheless, sources familiar with Boeing’s plans to get the grounding of the MAX lifted said that the light that illuminates when the two angle of attack sensors disagree will become a standard feature on the MAX from now on. For airlines that request it, Boeing will retrofit this warning light at no charge on previously delivered airplanes.
In addition, airlines that choose the option to put the angle of attack data on the primary flight display will not be charged extra for that feature.