Shrouded by the darkest clouds in its history from the unprecedented pandemic-driven collapse of the airliner business, Boeing has one glimmer of a silver lining left for 2020: The 737 MAX may finally fly passengers again.
The Federal Aviation Administration (FAA) in August laid out the proposed fixes for the design flaws in the MAX’s automated flight controls, starting a clock that could see Boeing get the green light sometime next month — with U.S. airlines then scrambling to get a few MAXs flying by year end.
On the two fatal MAX flights, an erroneous signal triggered software — the Maneuvering Characteristics Augmentation System (MCAS) — that repeatedly pushed each plane’s nose downward until it crashed.
Is fixing that flight control software good enough? Will the updated 737 MAX really be safe?
Former jet-fighter pilot and aeronautical engineer Bjorn Fehrm is convinced. Though he calls the design flaws that caused the two 737 MAX crashes “absolutely unforgivable,” he believes Boeing has definitively fixed them.
Fehrm, a France-based analyst with aviation consulting firm Leeham Company, says that with the updated flight control software, scenarios similar to the Lion Air and Ethiopian Airlines crashes simply cannot recur and the aircraft is no longer dangerous.
And Mike Gerzanics, a 737 captain with a major U.S. airline, is ready to fly a MAX — despite a Boeing whistleblower’s scathing critique that even with the planned upgrade, the jet’s decades-old flight deck systems fall far short of the latest safety standards and in the two MAX crashes created confusion in the cockpit.
Gerzanics, a former Air Force and Boeing test pilot and an aviation safety expert, concedes the dated MAX flight deck is far from ideal.
“It’s basically 1960s technology with some 21st century technology grafted onto it. The overhead panels could be right out of the 707,” he said. “But I’ve been flying it since 1996. I’m used to it. It’s safe and it works.”
Boeing’s missteps this year — from leaving behind debris in the wing tanks of the grounded MAXs to the latest quality control lapses in assembly of the 787 Dreamliner — have piled up and shaken public trust in the company’s safety assurances.
The FAA’s credibility is similarly shaken. The agency’s safety protocols that largely delegate oversight to Boeing itself — a system criticized by various independent investigations into the crashes — are still in place.
And the families of the 346 people who died in the Indonesian and Ethiopian MAX crashes remain bitter over the refusal of Boeing leaders to unequivocally admit that the poor design of MCAS brought the jets down.
In a statement, the FAA said that in collaboration with three major foreign aviation safety regulators it has extensively evaluated the MAX redesign.
“The modified aircraft will be fully compliant with the applicable rules, using the most conservative means of compliance,” the FAA said.
After a grounding that’s stretched now to 18 months and counting, and the close attention of regulators from all over the world, Boeing insists the MAX will be the most scrutinized and safest airplane ever when it comes back.
Still, even though the European and Canadian air safety regulators seem set to follow the FAA in green-lighting the MAX’s return to service, both are pressing Boeing sometime afterward to make further design changes.
And Boeing concedes that the new generation of younger pilots may need more training focused on automation. The FAA still has to finalize the pilot training it will mandate before the MAX can fly again.
Ralph Nader, the longtime consumer advocate and nemesis of powerful corporations, has a personal stake in examining the MAX crashes: His niece, Samya Stumo, died in the Ethiopian crash.
Nader questions even the basic stability of the MAX airframe. He says unnamed experts have told him that the MCAS software, even in its updated form, “remains a Band-Aid” to disguise “a physical aerodynamic design flaw.”
He’s called for a complete redesign of the airframe, claiming the MAX’s bigger engines placed further forward on its wings make the jet “inherently unstable.”
Aviation experts reject that idea.
A stable jet design ensures that if the airplane pitches nose-up for any momentary reason, say a gust of wind, the balance of the airframe makes it tend to right itself and pitch down to a normal position.
An unstable design, if the nose pitches up to a higher “angle of attack,” tends to pitch up even more, heading to a possible stall and complete loss of control.
Boeing put MCAS on the plane not to make it stable in maneuvers approaching a stall but to make it handle and feel exactly the same as the earlier model 737NG.
A former senior Boeing engineer familiar with the MAX design, who asked not to be identified, said this was a key design goal because major 737 customers such as Southwest, Alaska and Ryanair will be flying both NGs and MAXs and want to use the same pilot pool for both.
If the pilots had to think about different procedures on different 737s, it could lead to dangerous confusion.
“You don’t want pilots questioning, ‘What airplane am I on?'” said the former senior engineer. “There’s an inherent safety aspect to having them feel and operate the same way.”
To prove the plane’s stability, both Boeing and the FAA test pilots have now conducted extreme flight test maneuvers close to a stall, both with MCAS on and with the system turned off.
“If MCAS is deactivated, you can still fly the aircraft and it is not unstable,” said Fehrm. “The MAX without MCAS is a perfectly flyable aircraft.”
1960s-era flight deck systems
It’s also more efficient and cheaper for an airline with a 737 fleet that the MAX retains the 737 legacy flight deck. A pilot trained on the 737NG will be comfortable with the virtually identical instrument panel on the MAX.
The systems that feed information to the pilot on a MAX — providing for example the jet’s airspeed or its angle of attack, or a warning that something is faulty — are the same basic systems as on much earlier versions of the 737.
When Boeing certified the MAX, the FAA granted it exemptions so that these older systems were approved without having to meet regulatory standards designed for later, more automated jets.
After the second crash, Boeing flight controls engineer Curtis Ewbank filed an internal ethics complaint alleging that an upgrade to the air data systems — called “synthetic airspeed,” a software system installed on Boeing’s latest jet, the 787 — might have prevented the crashes but was rejected because of the cost.
Similarly, he wrote, after the FAA granted exemptions, flight crew alerts were not upgraded to the latest regulatory standards on the MAX.
When Ewbank reiterated his concerns in a letter to a U.S. Senate committee this summer, he listed a series of specific shortcomings.
For example, the MAX crew-alerting system activates a “clacker” making a very loud clicking sound to warn pilots when the jet is flying too fast. But it lacks an upgrade Boeing introduced after the 1996 crash of a 757 in the Dominican Republic killed 189 people.
Following that crash — Birgenair Flight 301 — Boeing decided pilots needed a way to acknowledge the overspeed warning and then silence the sound “to prevent crew distraction in critical troubleshooting times.”
This capability is now standard on all Boeing models except the 737. And Ewbank pointedly noted that on the Ethiopian MAX crash flight, the clacker “was sounding continuously during the last minutes of flight.”
Cost was certainly a major consideration when airlines told Boeing they wanted the MAX to look the same to their pilots as the earlier 737NG.
Gerzanics, the U.S. airline 737 captain, said that Boeing would have installed new flight deck systems if some airline customers had wanted them. But that would have required the airline to provide more pilot training in flight simulators and to buy extra spare parts.
He said a more modern crew-alerting system — one that for example allowed you to silence that overspeed warning — would be nice from a pilot’s perspective but not necessarily from an airline’s.
“An airline may not want to incur increased costs when they have a system that works,” Gerzanics said.
And it does work, said Fehrm, the Leeham analyst, adding that over 50 years the 737 has proven it’s “fundamentally a sound design.”
“There is no better testament to the safety of an aircraft than millions of flight hours with a very low accident rate,” he said.
Boeing’s view is that, aside from fixing MCAS, it’s better not to add extra bells and whistles to an airplane that otherwise had a good safety record, not just to save costs but also to maintain safety.
Dropping a new software system such as Ewbank’s synthetic airspeed into the middle of an old system architecture is a complex task that would require significant design and test resources. The former senior Boeing engineer who worked on the MAX said it would risk unintended consequences in some unforeseen flight scenario.
“You’ve got to be very careful anytime you want to add some new feature to a very proven reliable airplane,” he said.
Peter Lemme, a former Boeing engineer specializing in automatic flight controls, agreed. He said that after Boeing’s 2011 decision to upgrade the 737 rather than design an all-new plane, it’s best not to mess too much with the old 737 systems architecture.
“It would have been better to build an all-new narrowbody design,” Lemme said. “But the die is cast. It’s best to leave it alone.”
Still, European regulator EASA as well as Transport Canada are asking for flight deck design changes to address at least some of Ewbank’s concern about multiple crew alerts that caused cockpit confusion on the two crash flights.
After the two MAX crashes, both safety agencies are dissatisfied that a faulty angle of attack sensor not only activated MCAS but also inundated the pilots with multiple confusing warnings.
EASA doesn’t believe the 737’s two angle of attack sensors are enough, since if they differ, the computer won’t know which is correct. It’s pushing for some way to add to the MAX a third angle of attack measurement.
That could be some kind of software-derived, “synthetic” measure — something perhaps like Ewbank’s synthetic airspeed.
But EASA said that isn’t an immediate risk to flight safety and so the modification can come after the MAX returns to service.
Transport Canada focused particularly on the “stick shaker,” an alert that vigorously vibrates the pilot’s control column to warn of an approaching stall.
In a statement, Transport Canada said it will require Boeing to add some way for pilots to disable the stick shaker if it goes off erroneously, “to reduce pilot workload and distraction.”
Boeing has proposed for now that the pilots could pull certain circuit breakers to stop the stick shaker, though that’s not seen as a good long-term fix. Boeing is working to develop an alternative means of stopping an erroneous stick shaker that could be added after the MAX returns to service.
In its statement, Transport Canada said that if needed it will take unilateral action to mandate “supplementary procedures and training in Canada.”
And the agency added that since the same stick shaker system is also on the 737NG, a review of whether to require the same modification on that jet “is ongoing.”
As a solution to EASA’s concerns, Boeing has continued to resist Ewbank’s idea of adding synthetic airspeed.
The Boeing senior engineer said the company hopes that with MCAS fixed, the stick shaker silenced and pilots trained with new alert checklists, that will prove enough to satisfy EASA, too.
EASA, which this week completed its own set of MAX flight tests in Vancouver, B.C., declined to comment.
Pilot skills needed
Boeing has conceded that the assumptions it made about how pilots would react to a malfunction of the MCAS system proved totally wrong.
This has led to broad questions about whether the explosive growth of the worldwide pilot cadre in the last 10 years has produced pilots less skilled at handling an airplane with older technology like the 737.
Historically, U.S. airline pilots typically came up through the military, then flew regional aircraft before promotion to mainline jets. This gave them a broad range of aircraft experience, including flying manually with minimal automation — sometimes referred to as “flying by the seat of the pants.”
On the 737, the flight surfaces are moved directly via cables, giving the pilot a tight physical feel for how the surfaces move in response to control column commands.
Later Boeing planes, the 777 and 787, are “fly-by-wire” with the control surfaces moved electrically by computer after pilot input. Even then, Boeing lets the pilot overrule the automation.
In contrast, on Airbus jets, which are also fly-by-wire, the automated flight control software won’t allow a pilot command to move a surface more than the computer permits.
Despite these divergent safety philosophies, the Airbus A320 rival to the 737 has a very similar safety record, no better.
Today, there are fewer pilots moving up the ranks by flying aircraft that require seat-of-the-pants skills.
737 captain Gerzanics said, “The pilot pool has changed and moved away from flying older technology airplanes.”
“For the 737, it’s a change for the worse,” he said.
This is not only a MAX issue. Both Airbus and Boeing will have to adapt future new airplane designs so they can be flown safely by pilots less capable of handling seat-of-the-pants flying.
For current airplanes, including the MAX, the manufacturers and the airlines will have to gear up training and skills checks and sort out pilots who are demonstrably not apt at handling an aircraft that requires more from the pilot.
“We need a broader look at the spectrum of pilots who are flying,” said the former Boeing engineer. “Boeing has recognized that.”
The FAA and foreign regulators are still working on the updated MAX flight manual checklists and the details of the mandatory flight simulator training all pilots will have to complete before they can fly the MAX.
Glitches likely ahead
One thing Boeing is gearing up for when the MAX begins scheduled flights again is intense scrutiny of anything more going wrong, however minor.
For airplanes in regular service, flight diversions happen routinely for various reasons, and planes land safely.
“We’ll have to watch the MAXs when they come back. The minute you have a MAX divert, it will cause people to become a bit nervous,” said the former Boeing engineer. “Boeing will be on top of that. We know something can happen.”
Fehrm, the former fighter pilot, barely contains his anger at Boeing over the design of MCAS. He calls “really criminal” the way the design failed to deactivate the system once the Lion Air and Ethiopian pilots first countered it.
But he’s satisfied that can never happen again. He’s ready to board a 737 MAX.