Equipped with new systems and powered by more efficient engines, the 737 MAX family is the fourth generation of the Boeing 737 series. When the MAX-8, the first member of the 737 MAX family, took to the skies for the first time on January 29, 2016, no one knew how the beginning of this story would unfold.

Entering service with the Malindo Air fleet for the first time on May 22, 2017, MAX family airplanes became the fastest-selling aircraft model in Boeing history, accumulating over 5,000 orders in a short time. However, in the continuation of the story, these statements of success and pride were replaced by tragic, painful, and dubious ones. Entering the market like a perfect storm, it looks like MAX aircraft will be at the top of the list of the most controversial aircraft models in aviation history!

Problems started with the design

Wanting to reduce the production costs and to not fall behind its European rival Airbus A320 in the single-aisle aircraft market, Boeing faced some problems in the design process of the 737 MAX aircraft. Providing 14% better fuel burn, the new generation CFM International LEAP-1B engines developed for the new aircraft were larger than the engines used on previous models. Therefore, Boeing raised the landing gears and placed the engines higher and further forward from the aircraft’s fuselage. However, these actions changed the airplane’s center of gravity and affected its flight performance especially during the climb, increasing the aircraft’s angle-of-attack (AOA) all too often.

Regarding this hazardous situation, a system called MCAS (Maneuver Characteristics Augmentation System) was installed to the aircraft for the first time in Boeing history, to prevent the aircraft from entering an abnormal state called stall wherein the angle-of-attack increases beyond a certain point such that the lift begins to decrease. Thanks to this new system, when the nose of the aircraft was pitched upwards due to the increased angle-of-attack during the climb, the airplane could automatically adjust the trim, pushing its nose down. However, it was clear that something was not going right…

Back to back 737 MAX crashes

Then the demoralizing incidents began to come one after another. On October 29, 2018, Lion Air’s 737 MAX-8 crashed 11 minutes after its take-off in Jakarta, and on March 11, 2019, Ethiopian Airlines 737 MAX-8 crashed 6 minutes after its departure from Addis Ababa. The Ethiopian Airlines airplane involved in the accident rolled out of the factory four months in advance of the incident and flew about 1,200 hours operationally, while the Lion Air aircraft rolled out of the factory 11 months prior and had flown merely 800 hours up to the accident.

Having two fatal accidents that caused 346 deaths within a short span of five months was enough to link these crashes with each other and raise questions about the safety of the newest aircraft model built by the oldest and perhaps the strongest aircraft manufacturer. Both accidents were very similar to each other, and all the evidence pointed to the MCAS system. Something went unquestionably wrong with Boeing’s newest and best-selling commercial aircraft model.

According to preliminary reports on the accidents, pilots were struggling to maintain control of the aircraft following the failures of the airspeed indicator and some other equipment during the take-off. It is believed that, because of the faulty readings from the angle-of-attack sensors, the MCAS system abruptly commanded the aircraft into a steep dive, and the pilots could not recover the aircraft from the persistence of nosediving.

Global Grounding of 737 MAX!

Following the second accident, the decision of the Civil Aviation Administration of China (CAAC) to ground all MAX airplanes was rapidly implemented by other countries. The Civil Aviation Authority of many countries banned MAX aircraft from their airspaces, as well as compelled MAX operator airlines to withdraw the airplanes from their fleets. Within about four days, the entire global fleet of 371 737 MAX jets were temporarily grounded until the manufacturer could prove the reliability of this aircraft. Boeing stock fell nearly 20% and the company experienced the most severe turbulence of its 102-year long history!

Pilots are concerned!

After the two deadly crashes, the pilots who flew Boeing aircraft also appeared to have serious problems and concerns about the aircraft. The database of the Aviation Safety Reporting System (ASRS), which was established by NASA to allow pilots to anonymously record the incidents they experienced, holds numerous aircraft-related problems reported by pilots from all over the world. When the reports are analyzed, it is clearly seen that the pilots were not entirely adapted with the aircraft, and they had some confusion about controlling the aircraft.

The audio recording of American Airlines pilots confronting Boeing experts about the MCAS system during a meeting after the Lion Air accident also received extensive media coverage. At the meeting, pilots blamed the MCAS system and claimed that the faulty system was the cause of the accident, however, Boeing Vice President Mike Sinnett stated that the investigation had not been completed yet and said “The crash investigation is still ongoing. No one has concluded that the MCAS system led to the accident.”

Was Boeing aware of the problems?

A statement by Boeing in this May revealed a timeline indicating that they were aware of a problem with the aircraft long before the Lion Air accident, but that they did not take any action on the case.

Analysts criticized Boeing’s unique software design as it was based on readings from only one angle-of-attack sensor on any given flight, leaving the aircraft vulnerable to a single point of failure in case of data inconsistency. It also claimed that Boeing did not test how the MCAS system would react if one of the angle-of-attack sensors failed.

In 2017, within several months after beginning 737 MAX deliveries, engineers at Boeing identified that the 737 MAX display system software did not correctly meet the AOA Disagree alert requirements. However, instead of fixing the problem immediately, Boeing decided to leave it to the next planned system software update.

Approximately a week after the Lion Air accident on October 29, Boeing added a line in the FAA’s Airworthiness Directive (AD), stating that the AOA Disagree alert feature is only available if the angle-of-attack indicator option is installed. It is not entirely clear whether Boeing had warned the airlines that purchased the 737 MAX jets about this issue. Many pilots alleged that the operations manual is notoriously insufficient, and they had not received any information during the training process on how to switch off the MCAS system.

All charges against Boeing also target the US Federal Aviation Agency FAA. There are allegations that the FAA overlooked the incident and did not request the necessary safety measures for the MCAS system from Boeing.

Boeing stated that, when the MAX airplanes return to service, all the aircraft will have an activated and operable AOA Disagree alert and an optional angle-of-attack indicator. All customers with previously delivered aircraft will have the ability to activate the AOA Disagree alert. Unfortunately, aviation regulations continue to be written in blood.

MCAS software updated

Although Boeing primarily focused on the deficiency of pilot training regarding the accidents, the grounding of the aircraft and other developments led the company to accept the possibility that both accidents had occurred due to a common reason. After the investigation, Boeing CEO Muilenburg apologized for the lives lost, acknowledging that the MCAS system, which pushed the aircraft’s nose towards the ground, played a key role in both accidents.

Boeing decided to release a software update for the MCAS system consisting of flight control regulations, panel indicators, operations manual and training of the cockpit crew. With the update, Boeing aims to prevent the system from activating and reacting to the wrong angle-of-attack data provided by only one sensor as in the case of previous accidents and plans to introduce a new set of cockpit warnings to alert the pilots against potentially dangerous situations.

The flight control system will now automatically crosscheck the data from both of the airplane’s angle-of-attack sensors. The MCAS system will not be activated if there is a discrepancy of 5.5 degrees or more when the aircraft flaps are closed. Also, the system will inform the pilots about the situation via an indicator in the cockpit, allowing the crew to counteract the system in the case of an emergency.

The MCAS system will no longer overrule the pilots’ commands or apply so much input to the stabilizers that the crew cannot counteract it. This will enable the pilots to deactivate MCAS at any time and to manually control the aircraft. Boeing will also provide a training program to help pilots better understand the MCAS system. No extra simulator training will be required for the pilots apart from the half-hour long PC-based online training.

Unlike its biggest competitor, Airbus, Boeing has so far considered the pilots as the sole authority in flight. MCAS software was developed as the only exception to this traditional approach. However, it didn’t take too long to realize what a fatal mistake this was.

When will the Aircraft Take-off Again?

Although Boeing previously announced that the update would be completed in 1-2 weeks and delivered to airlines and authorities, the company was able to complete the update in about 2 months. However, the aircraft are still in parking position in various regions of the world, for almost three months!

Boeing’s test pilots have flown with the updated software for more than 360 hours on 207 test flights and carried out concurrent simulator testing. The finalized reports were submitted to the FAA and aviation authorities of 8 countries by the company.

Boeing pilots completed the test flights with the new MCAS software. However, during the flight certification tests, the aircraft will be flied accompanied by FAA pilots to independently verify whether the software update complies with all safety regulations.

Boeing announced that the software could be delivered to all operators within a day following the approval of the update by the FAA and other aviation authorities, and it would take only an hour to install the update on the aircraft. Boeing also plans to organize a series of customer conferences across the globe before the 737 MAX jets start commercial flights again.

Not Suitable for Hot and High Airports?

Geographically high-altitude airports require longer runways and higher take-off speeds. Because the air is thinner at higher altitudes, the aircraft must accelerate faster to generate the required lift on the wings. The same condition also applies to airports located in hot regions, as the hot weather has similar air densities with higher altitudes.

The Addis Ababa Airport, where the Ethiopian Airlines accident took place, is in the high airport category with an altitude of 7,657 feet, while the Jakarta Airport where the Lion Air crash occurred is in the hot region airports category.

The official documents submitted to the International Trade Commission by Boeing during a lawsuit between Boeing and Bombardier in 2017, claims that 737 MAX jets are not suitable for operations at high altitude and hot airports. According to these claims, only the 737 MAX-7 can serve in such airports due to its size while the MAX-8, 9 and 10 models are not considered suitable.

Official documents submitted to the Commission indicates that at least 16 undisclosed airports in the United States are in the “the high and hot” category and not suitable for the operation of MAX-8, 9 and 10 aircraft.

All the controversy about 737 MAX accidents revolving around the MCAS software around the world, pushed aside the claims that the aircraft cannot operate at high and hot airports. No one knows if it has anything to do with the accidents, but it’s a little confusing that Boeing doesn’t make any statement on this topic and continues discussions regarding the MCAS system.

Who will compensate the airlines?

Compensating the airline companies for their financial losses due to the worldwide grounding of 737 MAX jests is another case. Insurance companies and Boeing must pay the tangible damages to the airlines.

What is certain besides the 346 people who lost their lives and the negative effects of the resulting panic, is that the operators of the aircraft are not satisfied with the current situation. Most airlines have publicly announced that they will seek compensation for their financial losses.

Southwest, Air Canada, American Airlines, China Southern, Norwegian, Air China, TUI Group, United Airlines, flydubai, SpiceJet and WestJet are still the largest operators of the aircraft. American Airlines operates a fleet of approximately 1,000 aircraft comprised of 24 737 MAX aircraft. The company used 737 MAX aircraft in 85 of its 6,700 daily flights. United Airlines, another US-based company, has fourteen 737 MAX-9 jets. The largest operator of 737 MAX aircraft with 34 jets in its fleet is Southwest and their operations with MAX airplanes correspond to 4% of their daily flights.

All the operators of the 737 MAX have taken various actions to minimize the tangible damage caused by temporary grounding. Some airlines changed their flight schedules and canceled some of their flights while others signed short-term aircraft leasing agreements.

A study by the independent aviation consulting firm IBA (International Bureau of Aviation) shows that the direct cost of 737 MAX aircraft grounding is around US$150,000 per day. For Boeing, this amounts to a US$55.6 million loss in a single day.

The calculation by the IBA is based on the airlines’ leasing or financing costs, personnel costs, parking fees, compensation payments arising from flight program changes and cancellations, rebooking passengers on other airlines and additional costs, regardless of whether the aircraft is flying or not. In addition, grounded aircraft still require maintenance and repair. Therefore, even after Boeing fixes the problems with the aircraft, the airlines will face some extra maintenance costs before the jets begin to fly.

As the occupancy rates and hence the cash income of the airlines in the Northern Hemisphere are expected to increase before the upcoming spring and summer season, every operation that the airlines could not complete in this period due to the grounding of their aircraft equates to a red alert for their revenues. This situation will cause Boeing to pay a tremendous amount of compensation!

The fact that many airlines are considering canceling their previous orders can significantly increase the loss that Boeing will suffer from.

737 MAX summaries of Turkish airline companies

Corendon Airlines became the first airline to add 737 MAX aircraft to its fleet in Turkey. Turkish Airlines has a total of 75 Boeing 737 MAX jets on order consisting of 65 MAX-8 and 10 MAX-9 models with a longer fuselage. So far, THY has received a total of 12 aircraft including 11 MAX-8 and one MAX-9. Turkish Airlines has grounded all its Boeing 737 MAX models until further notice from civil regulation authorities, and the jets are currently parked at Istanbul Airport. SunExpress was also preparing to receive its first MAX 8 aircraft in April.

MAX continues to be produced!

Boeing currently focuses on finding solutions that will allow the MAX planes to return to the skies and fly safely. Although the MAX airplanes have been grounded for nearly three months, Boeing continues to manufacture jets at its production center in Seattle without any breaks. Rolling out MAX jets from its final-assembly line at the remarkable rate of 52 aircraft per month before the incidents, Boeing temporarily throttled back the production rate to 42 aircraft per month. The rolled-out jets quietly wait for their deliveries.

The current workload of the US-based OEMs is quite hard. Boeing needs to compensate the airlines for their financial losses, convince them not to cancel their orders, win back the trust of both passengers and airlines regarding the safety of the aircraft, and solve the problems of the MAX jets as soon as possible. If Boeing doesn’t use its energy wisely and efficiently, the company will likely face quite a bit of trouble in the upcoming days. We will see what happens