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| 737 Max 8 |
This past Sunday, an Ethiopian Boeing 737 Max 8 aircraft crashed shortly after takeoff from Addis Ababa to Nairobi with 157 passengers and crew. There were no survivors. This is the second crash of a Max 8 variant of the 737 in five months after the crash of a Lion Air Max 8 last October.
An undocumented system was brought under scrutiny in the Lion Air crash and now questions are being raised as to whether this same system, known as maneuvering characteristics augmentation system (MCAS), might have played a roll in this latest crash. If that is found to be the case, the safety of the aircraft itself will be called into question.
What We Know
At the current time, the cause of both accidents is unknown as the accident investigation is still underway on the Lion Air crash and the Ethiopian Air crash investigation is just getting under way. The flight data recorders and cockpit voice recorders have been recovered from both accidents and are being analyzed.
The flight recorder data from the Lion Air crash suggests that the pilots were having control difficulty due to erroneous inputs from the aircraft's MCAS system which itself received faulty inputs from a malfunctioning angle of attack (AOA) sensor. It is this errant sensor and its maintenance history that investigators are focusing on.
Initial reports from the Ethiopian Air crash suggest that the aircraft experienced control difficulties shortly after takeoff. Data from a flight tracking and reporting system known as ADS-B show highly unstable vertical velocity and airspeed readouts which were similar to the airspeed and altitude excursions of the Lion Air mishap aircraft.
Unconfirmed reports from listeners on the frequency reported that the Ethiopian pilots stated that they had unreliable airspeed indications and were declaring an emergency.
And right now, that's it. There are similarities, but no confirmation that the same system brought down both aircraft.
Is It Safe?
Given that we know little about the cause of the first accident and nothing about the cause of the second, a grounding of this model aircraft is premature. I am qualified and current in this model aircraft and am confident that it is as safe as any aircraft flying. Airplanes sometimes crash. It is always a tragedy when they do, but barring a definitive indictment of the design, there is no reason to overreact.
Even should the MCAS system be found primarily at fault, the system can be completely deactivated by two easily reached switches on the center console of the cockpit. Why the Lion Air pilots didn't take this action is unknown, but the investigation should eventually reveal the cause. A similar malfunction occurred on a previous flight of the mishap aircraft, and those pilots took the correct action and landed uneventfully. Questions as to why the aircraft flew again without being properly repaired should be asked.
In the event of unreliable airspeed, which can happen to any aircraft independent of model, routine practice of this malfunction in the simulator should make it a non-event. I recently underwent this training myself, but the basics of pitch and power date back to Wilbur and Orville. Recognition is the toughest part, but after that, known pitch and power settings will keep the aircraft from stalling and in control.
I don't mention these questions to cast blame, but rather to answer critics who don't understand aviation or engage in magical thinking. The Max is still a 737 at heart and flies nearly identically to the other four models of the aircraft that I have flown. So yes, it is safe, and I'd gladly put my family on one and fly it myself with no reservations.
Captain Rob Graves is a veteran airline pilot and retired Air Force officer. He currently flies a Boeing 737 for a major American airline where he has over 25 years of experience. His Air Force career included instructing future USAF pilots in the T-37 primary jet trainer, aerial refueling in the KC-135 Stratotanker, and conducting worldwide logistics in the C-5 Galaxy cargo aircraft. He is the author of This is Your Captain Speaking, an aviation blog. It can be found at robertgraves.com. He also writes for Avgeekery.com.
Captain Rob Graves is a veteran airline pilot and retired Air Force officer. He currently flies a Boeing 737 for a major American airline where he has over 25 years of experience. His Air Force career included instructing future USAF pilots in the T-37 primary jet trainer, aerial refueling in the KC-135 Stratotanker, and conducting worldwide logistics in the C-5 Galaxy cargo aircraft. He is the author of This is Your Captain Speaking, an aviation blog. It can be found at robertgraves.com. He also writes for Avgeekery.com.