Editor’s Note: Boeing 737 MAX re-certification flights were completed in early July after the FAA expressed satisfaction with the OEM’s safety improvements. Pilots and test crew members from the FAA and Boeing put the aircraft through “a wide array of flight maneuvers and emergency procedures to enable the agency to assess whether the changes meet FAA certification standards.” FAA clearance of the aircraft could occur by September. This would allow pilot training to re-commence (see What’s Next for MAX Training?), leading to US carriers inserting the MAX into operations before the end of the year.


After being grounded for 15 months, Boeing 737 MAX re-certification flights may begin as early as today. Robert W. Moorman explores the turbulent history of the airplane, and Rick Adams outlines the steps to a revised training program.

This past year has been a trying one for Boeing Commercial Airplanes. The revenue-draining after-effects of back-to-back fatal accidents involving the company’s latest and last 737, the MAX, and the costly fixes to the aircraft’s software system remain a major concern for the iconic plane maker.

The timeline for the aircraft’s return to commercial airline service keeps slipping, although MAX production resumed in May 2020 at its Renton, Washington plant. Boeing stopped MAX production in January and all aircraft production in late March due to the Covid-19 pandemic. Latest reports speculate that the MAX will remain grounded until August 2020, at least.

Equally troubling for Boeing is the lack of confidence in the MAX by some airlines and passengers. Hundreds of orders have been deferred or cancelled. Airlines and leasing companies in March cancelled 150 MAX orders. In mid-April, GE Capital Aviation Services (GECAS) rescinded its order for 69 MAX aircraft, potentially worth $6.9 billion to Boeing at $100 million a copy. From January through the end of May, orders for the model dropped by 615 (though backlog was still at 3,776).

The aircraft remains a public relations eyesore for Boeing. The news media keeps the MAX story percolating. A number of trade and consumer publications questioned Boeing’s veracity on the initial MAX certification, including the Seattle Times, which wrote a series of Pulitzer Prize-winning articles on the problems with the aircraft. Boeing “misinformed FAA and airlines” about certain features of the MAX’s Maneuvering Characteristics Augmentation System (MCAS), the paper stated.

Members of the US Congress took the FAA to task as well, claiming the agency was lax in its oversight on MAX certification. At a public hearing on 17 June, lawmakers accused FAA Administrator Stephen Dickson of “stonewalling” their investigation into the original certification process – which occurred well before the former Delta Air Lines Senior VP of Flight Operations took over the beleaguered agency on 12 August 2019.

"I hear your frustration and it is not OK with me," Dickson said. "I am trying to promote a culture, both within the agency, and really with all of our stakeholders of transparency and openness."

News accounts asserted that Boeing “self-certified” the MAX initially, at least in part, and is at it again on re-certification, a claim the agency said is patently false.

“There is no such thing as self-certification,” said an FAA spokesman. “The FAA’s aircraft certification processes are well established and have consistently produced safe aircraft designs.” Initial certification of the MAX took five years and involved 110,000 hours of work by FAA personnel, including flying or supporting 297 test flights.

While FAA regulations don’t allow original equipment manufacturers (OEM) to self-certify, federal law authorizes the agency “to delegate to a qualified individual or organization the ability to conduct certain activities on behalf of the agency.” In this case, that organization was Boeing.

An October 2019 report by a panel of international air safety regulators said the FAA initially delegated 40% of the 737 MAX certification tasks to Boeing employees, and scope-creep grew over the five-year review process. The panel said that greater FAA involvement in the certification of the flight control software “would likely have resulted in design changes that would have improved safety.”

Safety advocates worry that delegating tasks to an OEM creates a blatant conflict of interest, particularly when the OEM has a plane undergoing certification. Ironically, Congress, which is known to criticize the agency following a fatal accident, may have added to the confusion on what is or isn’t self-certification.

“In recent successive Acts, Congress directed the FAA to streamline certification, including increased delegation to Organizational Designation Authorizations (ODA),” the FAA said, adding that the use of delegation has been an integral part of the FAA process since the 1920s. “Our delegation program is similar to organizational programs used in Europe and other countries, and therefore helps the United States maintain a level playing field with foreign competitors.”

Sen. Roger Wicker, Republican-Mississippi, who expressed "profound frustration" with the FAA's "lack of responsiveness" to most of his committee's requests for documents, and Sen. Maria Cantwell, Democrat-Washington, introduced bipartisan legislation – The Aircraft Safety and Certification Reform Act of 2020 – which seeks, if passed, to reform the way the FAA certifies aircraft. "Our bill will end any semblance of self-certification," Cantwell claimed.

Just prior to the hearing on the Hill, a Boeing engineer sent a letter to the US Senate Committee on Commerce, Science, and Transportation, alleging that “systemic” problems with the aircraft’s design “must be fixed before the 737 MAX is allowed to return to service.” Flight-deck systems specialist Curtis Ewbank, who had lodged an internal ethics complaint with Boeing management last year, said the MCAS is not the only serious issue, citing “numerous other flaws,” including systems which may also affect the safety of Boeing’s forthcoming 777X widebody.

Ewbank reportedly advocated, in 2014, adding a Synthetic Airspeed measurement system, which would monitor multiple sensors. He claimed his proposal was rejected by management because it would affect schedule/cost and require additional pilot training.

The engineer left Boeing in 2015 “in protest of management actions to rationalize the poor design of the 737 MAX,” returning to Boeing in 2018 to work on the 777X. After the second MAX crash, he filed his ethics complaint.

The Covid Conundrum

Adding to Boeing’s troubles has been the dramatic impact of the coronavirus pandemic on airlines, aircraft manufacturing and other facets of the air transportation business.

The International Air Transport Association (IATA) predicted in early June that half the revenue of the world’s airlines will evaporate in 2020, $419 billion, for a collective loss of $84.3 billion.

In May, Boeing furloughed 6,700 workers as a result of cancellations of commercial airliners and reduction of air travel worldwide due to the virus. The layoffs are part of a restructuring effort that calls for the reduction of 16,000 jobs. And yet production on the MAX has resumed.

Nevertheless, Boeing remains a viable, multi-faceted company, which is insulated somewhat by its various units. Boeing is organized into three core businesses: Commercial Airplanes; Defense, Space & Security; and Boeing Global Services. Boeing Commercial Airplanes has been led by Stan Deal since last October; in 2017, Deal had guided the stand-up of the services business, headquartered in Dallas, Texas, which includes commercial flight training services. BGS is now led by Ted Colbert.

The ongoing uncertainty of the MAX program weighs heavily on airline customers and plane maker alike. Richard Aboulafia, Vice President, Analysis, for aerospace consultancy The Teal Group, underscored the importance of the MAX to the aircraft manufacturer: “It’s easily Boeing’s biggest and most important program, so a return to service and production is extremely important.” He added: “The real problem is not the design itself, it’s the erosion of competitiveness for the larger variants, the MAX 9 and 10.”

Pandemic social-distancing policies have even forced teams from Boeing and the FAA to work remotely and pose challenges for test flights, which necessitate closer physical contact.

Everyone connected with the MAX program is keeping a low profile. Neither the plane maker nor US MAX operators – United, American and Southwest – are granting interviews on the airliner. Collins Aerospace, which provides large-format flight displays and other systems for the MAX, deferred all avionics-related questions to Boeing.

Nevertheless, CAT is able to update readers on the status of the MAX program through airline statements, the FAA and select MAX operators.

The FAA declined to provide a specific period when MAX can return to the skies. “The FAA has steadfastly stayed away from predicting when the aircraft will return to commercial service,” an FAA media spokesman said. “We continue to work with Boeing and will approve the aircraft when we are satisfied that it meets certification standards.”

Despite repeated delays on re-certification, the MAX’s return to commercial service is likely. Boeing told Tier 1 supplier Spirit Aerosystems in March 2020 to resume production of the MAX fuselage. Boeing’s initial contract with Spirit specified that the Wichita, Kansas-based company supply 216 fuselages. GE/Safran (CFM) is resuming production of the LEAP 1B engine, the exclusive powerplant for the MAX. The LEAP also powers Airbus’ A320neo family.

Airlines remain cautiously optimistic toward the MAX’s future. Southwest, a long-time user of 737 variants and the largest US operator of the MAX, removed the model from its published schedule through 30 October 2020, awaiting further guidance from the FAA and Boeing. Southwest CEO Gary Kelly has said he expects the MAX to return to service by the end of Q4.

Southwest’s first quarter 2020 Available Seat Miles (ASMs) figures decreased 6.7%, year-over-year, due primarily to the YOY capacity reduction of 17.1% in March 2020 related to the pandemic, as well as the MAX grounding. Southwest, which has 34 MAX aircraft in its fleet presently, has not received any additional MAX planes since February 2019. Subsequent to the MAX grounding, Boeing agreed to an arrangement where Southwest would take delivery of no more than 48 aircraft through the end of 2021, fewer than 27 MAX deliveries in 2020.

The coronavirus has taken its toll on airline revenue. As of mid-May 2020, Southwest had “350 aircraft in long-term storage or temporary parking.” Southwest and American operated the 737 MAX-8, while United flew the larger -9.

United and American have said they would not fly the MAX until September 4 and 7 April 2021, respectively. Both airlines expect to gradually phase in the MAX. American has a fleet of 24 MAX 8s, with 76 on order.

In early January, American reached a confidential agreement with Boeing for financial damages incurred in 2019 due to the MAX grounding. American’s board authorized that some of the settlement should be given to employees through the company’s 2019 profit-sharing plan, which is based on projected full-year financial damages due to the MAX grounding.

Air Canada removed the MAX in January from its schedule until 30 June, a timeframe which will need to be amended. The airline grounded its fleet of 24 MAX aircraft on 13 March 2019. Air Canada cancelled 11 MAXs this March so it could have flexibility to order other aircraft, according to CFO Michael Rousseau.

Ryanair, the Swords, Ireland-headquartered low-cost carrier, remains bullish on the MAX-8 high-density version, rebranded as the MAX-200. Ryanair ‘s MAX-8 will come with 197 seats. The airline has firm orders for the MAX-8 with options on an additional 75. As of late May 2020, Ryanair CEO Michael O’Leary indicated a desire to order more. The carrier expects to receive its first MAX sometime in Fall 2020. Some of those aircraft bound for Ryanair are built already and waiting for delivery.

O’Leary said recently he is pursuing a MAX-10 order and anticipates closing a deal after the MAX is cleared for service. “If the MAX is back flying in September, October this year, I will be very disappointed if we’re not in active negotiations with Boeing either this side of Christmas or early in the spring on an order for larger aircraft, the MAX-10s.”

The TUI Group, a multi-national travel service with five airlines in Germany, the United Kingdom, Belgium, the Netherlands and Sweden, had operated 15 MAX aircraft out of 72 ordered. The company said it remains committed to the plane but is not planning to re-enter the MAX into commercial service by August. No specific or general timeframe was announced.

In early June, TUI announced it would be compensated by Boeing for the estimated half a billion euros in losses last year and this year due to the MAX grounding.

“We are in constant contact with Boeing and EASA but don’t have a new indication when we will be able to operate the plane again,” TUI Group Corporate Communications stated. “It is a common understanding that the FAA would first approve the MAX and then EASA and others would follow.”

TUI also was asked if aircrews were undergoing revised initial and recurrent training presently. “We are awaiting the final decisions of the FAA and EASA how future training has to be set up. Latest expectations (before COVID-19) were that simulator training would be required. TUI will support all actions needed for a safe re-entry into service of the MAX,” TUI added.

Four of TUI’s five airlines were operating the plane before its grounding. All are expected to fly the plane again once it is recertified and after all modifications and training have taken place. However, future deliveries of the MAX have been pushed out.

TUI Group CEO Fritz Joussen said in mid-May that the travel giant was ready to resume travel activities. “People want to travel. Summer holidays are possible with clear rules,” he said. TUI told CAT it was developing new plans for a summer scenario. But before the planes could operate, the home country of its airlines needs to lift travel bans and mandatory quarantines and open their borders again.

Fixes & More Fixes

Boeing made numerous changes to the MAX following the grounding, not the least of which was MCAS, whose faulty software system was thought to be a factor in two highly publicized crashes.

First, 29 October 2018, the crash of Lion Air Flight 610, a MAX-8. The airliner was enroute from Soekarno Hatta International Airport in Jakarta to Depati Amir Airport in Pangkal Pinang when it crashed into the Java Sea minutes after takeoff, killing 189 passengers and crew. Five months later, a MAX-8 operated by Ethiopian Airlines, Flight 302, crashed minutes after takeoff from Addis Ababa Bole International Airport in Ethiopia, killing all 157 people onboard. The aircraft was enroute to Jomo Kenyatta International Airport in Nairobi, Kenya. Regulatory authorities worldwide grounded the MAX in March 2019, beginning with China on the 11th.

While an official cause of the Ethiopian accident has yet to be released (an interim report was issued this past March), the aircraft had recorded faulty angle of attack (AOA) readings on the flight displays during climb out, and related problems with the MCAS.

MCAS was installed on the MAX “to enhance pitch characteristics with flaps up and at elevated angles of attack.” MCAS function commands nose down stabilizer to enhance pitch characteristics during steep turns with elevated load factors, according to an Allied Pilots Association member message, which was sourced to Boeing.

On its website, Boeing details fixes and enhancements made to the MAX. Three additional layers of protection were added to the MCAS system, including software changes, additional redundancy and changes to the flight control systems. Boeing also redesigned how the airplane’s Angle of Attack Sensors (AoAS) work with MCAS. As of early May, more than 1,100-plus tests and production flights with new software had taken place.

No other 737 models have MCAS, which could be described as a modern anti-stall system. During aerodynamic tests of the MAX in 2012, engineers found that the aircraft had the tendency to pitch up during extreme maneuvers, which are required to gain certification. MCAS was the supposed solution. The problem was that the device would activate “on the inputs of a single sensor, instead of two factors considered in the initial plan,” according to the Seattle Times story, which reviewed Boeing proprietary information. Relying on a single sensor was risky because of the possibility of erroneous data. In the new Boeing scheme, both Angle of Attack sensors have to match before engaging the MCAS system. In addition to the second sensor, Boeing is including a warning light on all MAX aircraft to warn pilots of a faulty sensor.

According to Boeing, “MCAS will now only activate once and will never provide more input than the pilot can counteract using the control column alone.” Pilots will also be able to override MCAS at any time, which the Lion Air and Ethiopian pilots were not able to do in repeated attempts.

Boeing 737 MAX aircraft MCAS

Image credit: Indonesian National Transportation Safety Committee (KNKT).

However, European regulators are not satisfied; they want to add a third AoAS, similar to the Airbus A320. They may also push for a Synthetic Airspeed system, which is on Boeing 787 aircraft, but possibly not to be added until after the MAX returns to service.

Moreover, in a recent reminder to maintenance workers, the FAA urged extra care around the AoA vanes, which are on the sides of the aircraft. Since the early 1990s, at least 140 Angle of Attack Sensors units have been damaged on the ground or by birds.

The MCAS was initially intended to be limited function artificial intelligence software, using data from two sensors for wind resistance and force. However, Boeing removed the force sensor and also gave the MCAS more aggressive control over the plane.

Another concern of MAX pilots involved basic MCAS training. MAX pilot groups stated after the Lion Air accident that they were unaware of the procedures for turning off the MCAS. The Airline Pilots Association (ALPA), the Allied Pilots Association (APA) and the Southwest Airlines Pilots Association (SAPA) roundly criticized Boeing for not providing detailed information about MCAS and how to disengage the system. Even with training, pilots are reported to have failed to override the system in simulations.

In other internal changes, Boeing is creating a permanent Aerospace Safety Committee of Boeing’s Board of Directors to further strengthen the company’s safety culture.

Another issue has surfaced that could impede re-certification. Boeing could be required by the FAA to separate wire bundles on the MAX to eliminate the possibility of a short-circuit in various onboard systems. Boeing is opposed to separating wire bundles, a process that is commonplace in commercial airliners, as they would most likely need to separate the wires on all the MAXs built to date (387 delivered before grounding and another 400 or so awaiting delivery).

And yet another issue – the FAA last week finalized a directive requiring inspections of electromagnetic shielding on top of 737 MAX engines, which the agency warned “could potentially lead to a dual-engine power loss event and/or display of hazardously misleading” data and result in a “forced off-airport landing.”

Tick-Boxes for the MAX Comeback

Boeing must meet five key milestones before the MAX can return to commercial service:

1. Simulator Certification Session: A multi-day simulator evaluation with the FAA must be completed to ensure that the overall software systems perform as intended. That milestone has been completed, according to Boeing.

2. Line Pilots Crew Workload Evaluation: Multi-day simulator session with airline pilots to assess human factors and crew workload under various test conditions.

3. Certification Flight Test: Pilots will conduct certification flights of the final software update.

4. Final Submittal to the FAA: Following the FAA certification flight, Boeing will submit the final certification deliverables to support software certification.

5. Joint Operational Evaluation Board (JOEB) Training Evaluation: JOEB, a multi-regulatory body, will conduct several sessions with airline pilots and regulators to validate training requirements.

Finally, the Flight Standardization Board releases a report for a public comment period. Final approval of the training standards follows.

The FAA is well aware that Congress, safety advocates, airlines, pilot groups and others are scrutinizing its re-certification of the MAX. Nevertheless, the agency said it is following the same processes this time around. The work includes: review proposed designs and methods to ensure that they (and the overall airplane) comply with FAA standards; evaluating the airplane to determine required maintenance and operational suitability for reintroduction of the aircraft into service; and working with other regulatory agencies on their approval of the aircraft, which is based, in part, on work completed by the FAA already.

The MAX is expected one day to re-join airline fleets globally. So, the question is no longer if, but when it returns to commercial service. And how much of a competitor it will be against the Airbus A320neo.

Will passengers embrace the MAX again? In one survey, 21% of fliers said “Never,” 23% planned to wait a year or more, and only 19% said “Immediately.” If given a choice between a MAX and another aircraft type, more than half said “The Other One." 

FAA Administrator Dickson and his deputy, Dan Elwell, both former airline pilots, plan to fly the plane in an attempt to reassure the public. Dickson pledged that he would not sign off on the aircraft until he is satisfied that he would put his own family on it "without a second thought."

John Cox, a 49-year aviation veteran and CEO of Safety Operating Systems, stated: “I’m confident in the re-certification process and will personally fly on the 737 MAX when it returns to service." 


CAT Editor Rick Adams contributed to this article.