Did Boeing overplay its hand with the 737 Max?

Pilots are expecting a reaction from the plane manufacturer after the Lion Air-disaster.

Billed as the fastest-selling plane in Boeing’s history, enthusiasm about the latest version of the Boeing 737 has curbed substantially over the last two months. After the Lion Air crash, the Indonesian safety bureau pointed the finger at the plane’s design, in particular the new MCAS-feature. Now the pilots question the Boeing policy to not warn them about this new hidden protection. The company has since promised a software fix to avoid another computer crash.

A Boeing 737 Max with the characteristic winglets and CFM Leap engines

By Tom Dieusaert*

“I am outraged,” says Martín Villagra, an Aerolineas Argentinas instructor and pilot of the Boeing 737NG series and 737 Max. “I am a Boeing man, but here we have a major flaw but they camouflaged it and blame the pilots.”

Martin Villagra, pilot and 737 Max instructor at Aerolineas Argentinas

Villagra is talking about the MCAS feature that suddenly kicked in on the fatal Lion Air Flight JT610 on October 29 and triggered a series of 26 heavy nose-down inputs. The result was a loss of control as the pilots clearly didn’t understand what was happening.

Villagra shows me the Flight Crew Operations Manual (FCOM) of the Boeing Max. “There are 1,400 pages and only one mention of the infamous Maneuvering Characteristics Augmentation System (MCAS) … in the abbreviations sections. But the manual does not include an explanation of what it is…”, says Villagra.

“Before Boeing came out with that safety bulletin on the MCAS, (the pilots) thought that on the fatal Lion Air flight, there had been a series of nose-down inputs from the Elevator Feel System (EFS),” Villagra said. The EFS is a feature that helps the pilot move the control column when a there is a stick shaker stall warning (on Boeing). “But the EFS never acts by itself, so we were astounded when we heard what the real reason was.”

In the aftermath of the Lion Air disaster every Boeing 737 Max pilot in the world knows what MCAS stands for. And few are happy with that knowledge. Pilots with Southwest Airlines, the first company to place orders for the new Boeing, were livid when they heard about the system. They immediately asked Boeing for an explanation. The feeling was similar among American Airlines pilots.

More ground school, more simulators

Dennis Tajer, APA’s spokesman

“We are deeply concerned,” says Dennis Tajer, the Allied Pilots Association (APA) spokesman. “It’s a very different plane than the previous 737NG, but that was not what they told us: To qualify for flying the MAX, we just had to do some extra reading on the iPad. Quick training was all that was needed.”

American Airlines started with 20 Boeing 737 MAX in its fleet, 20 more are to arrive in the coming weeks from a total order of 100. But the company does not have a Max simulator.

“We have been asking the company for extra ground school and specific simulators,” Tajer said. “Southwest already has ordered three of them, to be delivered in 2019. We wouldn’t have been so aggressive about this, if it weren’t for what we heard after the Lion Air crash.”

Tajer criticizes Boeing for withholding crucial information about how the MCAS works. “We were appalled!” he said. “Afterwards, Boeing said “just run the (runaway horizontal trim) checklist,” but you have to imagine being in the cockpit with instruments conflicting on altitude, speed, and stick shaker (the Boeing stall prevention feature). All these distractions. Then you retract flaps and the MCAS kicks in. There is gunfire going on around you. It’s not just some sterile event that you are seeing at your desk.”

Aerolineas Argentinas instructor Villagra agrees: “I read in the Indonesian report and in Boeing communications that the other Lion Air crew (who battled the same problem a day earlier) succeeded in solving the problem by cutting off the electric trim motor. This annoys me because it suggests that the other pilots knew what was going on. They couldn’t know what was going on. Maybe they acted by instinct.”

Anti-stall system or steering aid?

There has been a lot of controversy about the MCAS system and some confusion, too. It is not an anti-stall protection as it has been erroneously labeled. Is it an Airbus-like protection? Or more of a power maneuvering aid? And if it’s an aid, how can it move by itself against the will of the pilots?

“It seems to be a mixture of both,” says Tajer. “It’s actually designed to give a pilot who is flying the Max the same feeling as if he were on a 737NG. Hence the reason we supposedly didn’t need extra training. However the 737 Max is a totally different plane.”

The big difference between the last generation B737 and the older NG’s are the powerful CFM Leap engines. These are 15% more fuel efficient — the main reason for its success — and as a result the B737’s are now flying medium range hauls of 6 hours. But the heavy turbo jets — located more forward on the wing — are one-third bigger than their forbearers, causing the machine to pitch up heavily. This is where the MCAS comes in.

“Probably Boeing added the MCAS to the new 737 model to meet certification requirements,” says Villagra. “The MCAS is an aid — like power steering in a car — to help pilots lower the nose more quickly in a situation of high angle of attack. Without the MCAS, the control column would be physically harder to handle and it would take more time and loss of altitude to recover from an upset.”

However, in some cases — as happened on Flight 610 — the MCAS moves by itself. “It’s similar to an Airbus Alfa Prot system, but a primitive Alfa Prot,” says Villagra. “Boeing has decided to put this automation feature on a mechanical plane and it just doesn’t fit. The problem is really that the 737 is a machine from the 60s and they have been continually tweaking the model. It’s like putting an iPhone chip in an old bakelite rotary phone.”

Lion Air 737–800 Max

Software fixes

The pilots are at loggerheads with Boeing and the MCAS system not only because the Seattle-based company didn’t tell them about it, but also because the feature itself seems technologically precarious.

Reuters reported that Boeing sat down with American Airlines pilots and has promised a software fix within 6 or 8 weeks. The fix could mean more redundancy, because at present the MCAS can be triggered after only one defective angle of attack sensor or a flawed data computer sends out an (incorrect) stall warning. Why the MCAS wasn’t linked to the two (independent) angle of attack systems is not clear.

Martín Villagra thinks there might be another possible solution. “Now the MCAS is inhibited when the Auto Pilot is engaged or with extended flaps. It would be much easier when there is a problem with unreliable airspeed (UAS) or speed trim fail, that the MCAS system would be inactive too,” he says. So, it ought not be too difficult to reprogram.” “In case of UAS we would fly with raw data,” the Argentinian pilot says, “but with no surprises.”

Flying with raw data means handing the responsibility back to the pilots. But airlines and aircraft manufacturers seem to have little faith in basic airmanship. In light of the recent controversy surrounding the Boeing MAX, the Argentinian company has compelled their pilots to fly the MAX exclusively on Automatic Pilot.

Senior Boeing officials have recently stated that the MCAS feature wasn’t revealed because they feared pilots would not understand the intricacies of the system. APA spokesman Tajer couldn’t disagree more.

“Boeing has no excuse for not briefing the crews: On both the NG and the MAX, when you have a runaway trim stab this can be stopped temporarily by pulling the control column in the opposite direction. But when the MCAS is activated because of a high angle of attack, this can only be stopped by cutting the electrical trim motor. And this wasn’t in the Manual.” So, no more secrecy, Tajer insists.

“We are saying: First of all: Don’t do that again,” he said. “And second, give me all the information you got, full disclosure. Then we’ll decide which information to feed the pilots. We have a right to know.”

*Tom Dieusaert (°1967) is a Buenos Aires-based journalist who writes about aviation. Last year he published “Computer Crashes: when airplane systems fail”