The Boeing 737 MAX 8 is a new plane that had its first flight in January 2016. Despite its short time on the market, the MAX 8 has been involved in two tragedies in fewer than five months: the Ethiopian Airlines Flight 302 crash on March 10, 2019, and the Lion Air Flight JT 610 crash on Oct. 29, 2018. The 737 MAX 8 is a modified version of the 737 and is designed to be more fuel-efficient than previous models. Changes to the aircraft’s engine placement, however, resulted in engineers altering the angle of attack sensors and modifying the plane’s stall warning and recovery software. Pilots say they were not told about those changes and were not given training in the new system, putting lives at risk.
Boeing 737 MAX Facts
- It comes in three sizes and can seat between 126 and 220 passengers
- Its engines have a fan diameter of 69.4 inches, compared with 61 inches on the previous 737
- It is 14 percent more fuel-efficient than the previous 737 aircraft
- It has a quieter engine thanks to a rear outlet designed to cut back on noise
- Its control display panels are similar to those in the 787
- There are approximately 350 737 MAX planes in service around the world
Boeing MAX 8 Approval
To make the MAX 8 more fuel efficient, Boeing used larger engines, but to accommodate the larger engine size the company altered where the engines are attached to the wings. Doing so, however, created a situation in which the plane tends to pitch upward, potentially causing a dangerous stall. To counter this, Boeing added an autopilot system that would push the nose down if angle-of-attack sensors indicated the nose was too high.
The 737 MAX has two angle of attack sensors. If the sensors malfunction, the system—known as the Maneuvering Characteristics Augmentation System or MCAS—would automatically push the plane’s nose down. The problem is that pilots were not made aware of the new system in the aircraft and were not trained in using it or responding to emergencies if the system was unnecessarily triggered.
When Boeing made changes to introduce the 737 MAX it convinced the Federal Aviation Administration (FAA) that pilots did not need to be told about the change or trained in understanding the new system, arguing that the new system was fundamentally similar to previous versions. This decision left the pilots woefully unprepared to determine what was going wrong and how to address it, and put the lives of the passengers and crew in jeopardy.
Boeing 737 MAX Operators
The United States, China and Canada are among the largest users of the Boeing 737 MAX 8. As of Feb. 2019, Southwest Airlines has 34 373 MAX 8 aircraft while American Airlines has 24 and United Airlines has 14 MAX 9s.
Boeing 737 MAX 8 Crashes
On March 10, 2019, Ethiopian Airlines Flight 302, operating a Boeing 737 MAX 8, crashed approximately 6 minutes after taking off from Addis Ababa, Ethiopia, killing all 157 people onboard. Ethiopian Airlines Flight 302 reportedly had difficulty maintaining a stable climb. The pilot requested a return to the airport, but the Boeing 737 MAX 8 crashed approximately 39 miles southeast of the airport, killing all on board.
In early April, investigators released the preliminary report on the Ethiopian Airlines crash. The report noted that the pilots fought against the aircraft’s automated flight systems from moments after the plane took off. Although the pilots followed safety procedures, they could not regain control of the plane, and it crashed. Investigators noted that, shortly after the plane took off, the angle-of-attack sensor sent erroneous information to the MAX’s automated flight system, which activated the left stick shaker. The report states that the airspeed, altitude and flight director pitch bar values from the left side were lower than the right side values and remained lower until moments before the plane crashed.
Early reports suggested the plane suffered foreign object damage, which might have caused faulty angle of attack readings, but the preliminary report found no evidence that any object struck the plane.
The MAX 8 plane was delivered to Ethiopian Airlines on Nov. 15, 2018 and had 1330.3 hours at the time it crashed. Meanwhile, investigators said the crew was fully qualified to fly the plane.
The preliminary report does not place blame for the crash, rather it sets out the circumstances that led up to the tragedy. A full report is expected in approximately a year. Despite not placing blame, the preliminary report states the pilots followed all emergency procedures correctly.
On Oct. 29, 2018, Lion Air Flight JT 610 crashed approximately 13 minutes after taking off from Soekarno-Hatta International Airport in Jakarta. All 189 people onboard the plane died when it crashed into the Java Sea. Shortly after takeoff, the pilot requested to return to the airport due to “technical difficulties.” A preliminary report following the crash did not place blame for the tragedy but did note issues with the angle of attack sensor.
As more news comes in from the Lion Air crash investigation, reports have emerged that an off-duty pilot on a MAX 8 aircraft saved lives by accurately diagnosing the problem. One day before it crashed, the same Lion Air plane experienced the exact same issue with the anti-stall system. Fortunately for everyone onboard the plane, the off-duty pilot in the jump seat figured out what the problem was and told the crew how to resolve it. Unfortunately, none of the pilots aboard detailed to the airline exactly what they experienced and what they did to solve the emergency.
After the crew stopped power to the trim system’s motor, the flight carried on as normal. Indonesia’s safety committee reports the crew that managed to resolve their issue noted that the plane needed maintenance but did not specify issues with the anti-stall system.
The following day, the pilots for Ethiopian Flight 302, operating the same model 737 Max plane, experienced the same climb deviation and stall recovery system malfunction, but were unable to diagnose the problem even though they frantically looked in the operating handbook for guidance and found no help. The failure of the handbook to contain emergency procedures for the condition created by the MCAS system, and the lack of training given the pilots, is now being investigated as causes of the crash.
Reports from the cockpit recording indicate the captain asked the first officer to refer to the flight manual to determine what was going wrong with the plane. Sources who heard the recording said the pilots discussed airspeed and altitude but were not able to identify the cause of the plane’s issues.
Optional Safety Features Missing
Boeing had two safety features that might have alerted pilots to issues with the angle of attack sensors—or at least given them more information as to what they were fighting against—but those features were optional upgrades and were not standard on the 737 MAX aircraft. Neither Lion Air nor Ethiopian Airlines opted for the upgrades.
The first upgrade is an angle of attack indicator, which displays information from the angle of attack sensors and allows pilots to verify the data is correct. For example, if the sensor indicator shows the nose as being too high but the plane is relatively level, the pilot knows the sensor’s information is flawed. The second upgrade is called a disagree alert. It lights up if the plane’s two angle of attack sensors show different values, which would also show that one is erroneous.
Boeing reportedly did not consider either of the upgrades vital to ensure safety, though they could have alerted the pilots to what was going wrong with their aircrafts, possibly averting disaster. Since the tragedies, Boeing has said both upgrades will be offered on all aircraft for no charge.
Boeing Admits Flight Control System was a Factor in Crashes
Boeing issued an apology for the crashes and admitted that the automated flight control system on the two 737 MAX aircraft likely played a role in the tragedies. Following the release of the Ethiopian Airlines preliminary report, Dennis Muilenburg, Boeing CEO, said, “…it’s apparent that in both flights the Maneuvering Characteristics Augmentation System, known as MCAS, activated in response to erroneous angle of attack information.”
US 737 MAX 8 Incidents
Pilots in the US have reported at least 5 incidents in which they had difficulty controlling their Boeing 737 MAX 8 aircraft, including scenarios that are similar to the Lion Air and Ethiopian Airlines crashes. This includes a November 2018 incident in which the plane took off, autopilot was engaged and within seconds, the plane’s nose pitched down, triggering the warning system. A pilot disengaged the autopilot, even though nothing in the emergencies section of the pilot’s operating handbook covered the event, and the flight continued as normal.
In one report, the pilot complained that manufacturers, the FAA and airlines would allow pilots to fly aircraft without adequate training or documentation regarding “the highly complex systems that differentiate this aircraft from prior models.”
A Boeing 737 MAX 8 made an emergency landing in Florida on Tues. Mar. 26, 2019, cutting short a flight to California. The plane returned to Orlando International Airport after pilots reported issues with one of the engines shortly after takeoff. The MAX 8 was on its way to California, where it was to be stored while the fleet of 737 MAX aircraft are grounded. Officials have not said if the issues this plane experienced are linked to those identified in the Lion Air and Ethiopian Airlines crashes, but the Federal Aviation Administration is investigating the incident.
There were no passengers on the plane at the time of the emergency landing. Rather than going to California, the plane will be kept in Orlando for a maintenance review.
Airlines that Purchased the Boeing 737 MAX Aircraft
- Aerolineas Argentinas
- Air Canada
- Air China
- Air Europa
- Air Lease Corporation
- Air Niugini
- Air Peace
- Alaska Airlines
- American Airlines
- Arik Air
- Aviation Capital Group
- Blue Air
- BOC Aviation
- CBD Aviation
- China Eastern Airlines
- China Southern Airlines
- CIT Aerospace
- Comair Limited
- Copa Airlines
- Corendon Airlines
- Donghai Airlines
- Eastern Air Lines
- Enter Air
- Ethiopian Airlines
- Garuda Indonesia
- GE Capital Aviation Services
- GOL Airlines
- Hainan Airlines
- ICBC Leasing
- Jet Airways
- Korean Air
- LOT Polish Airlines
- Lion Air
- Malaysia Airlines
- Mauritania Airlines
- Nok Air
- Norwegian Air Shuttle
- Okay Airways
- Oman Air
- Pimera Air
- Qatar Airways
- Ruili Airlines
- Shandong Airlines
- SMBC Aviation Capital
- Southwest Airlines
- Sriwijaya Air
- Travel Service
- TUI Group
- Turkish Airlines
- United Airlines
- VietJet Aviation
- Virgin Australia
- Xiamen Airlines