Six Minutes to Eternity
The Sky Harbor International Airport, Phoenix, USA. On the 1st of July, I was waiting there for a flight to New York. As there were nearly 2 hours before boarding the aircraft, I turned to Whatsapp chats. Forwarded was a Churchillian episode I had read nearly 50 years ago. It was like this: “During the second world war, the British prime minister Winston Churchill was flying in an amphibious military plane to an unknown destination. To pass time Churchill began taking some flying lessons from the pilot. Later, when the aircraft touched down in the water, the pilot thought Churchill had landed the plane, and Churchill thought the pilot did it. Then, the embarrassed pilot remarked that they were falling between two stools. But, the indomitable and quick-witted Churchill quipped it was more like a stalling between two fools.”
The word STALLING rang a bell, and my thoughts vectored to the recent crash involving 2 Boeing 737 aircraft due to the failure of the stall prevention system. Feeling a bit uneasy, I got up and walked to the large windowpane overlooking the tarmac. Down below, on the apron, were many planes at various stages of flight preparations. Most of them were Boeing 737 aircraft. Since 60s Boeing 737s are the workhorse of the domestic Airlines in the US. They have a very high safety record. But, recent crash and the subsequent grounding of new aircraft put a question mark on Boeing’s unblemished safety record.
Beyond the apron was a group of aircraft parked, apparently, for a longer period. As an aircraft engineer, my curiosity was aroused. On enquiry, I was told those aircraft belonged to Southwest Airlines and that they were grounded for the past five months by the US regulator, the FAA (Federal Aviation Administration). Then I realized that they were part of the brand new Boeing 737 Max 8 aircraft fleet grounded globally after two successive crash - one in Indonesia and the other in Ethiopia. Boeing 737 Max 8 was the latest addition to the Boeing 737 family.
On October 29th last year a Boeing 737 Max 8 of the Indonesian carrier Lion Air crashed into the Java Sea 10 minutes after takeoff, killing all 189 people on board. A similar fate awaited the Ethiopian carrier on the 30th of March, this year. 6 minutes after takeoff Boeing 737 Max 8 of the Ethiopian Airlines lost control and crashed into the countryside killing all 157 people on board. One of the rescue workers rushed to the crash spot exclaimed that the earth had swallowed the plane. There were no survivors, no bodies: only human remains. The out of control plane diving at transonic speed turned into a virtual missile. It tunnelled into the ground creating a crater 100 feet in diameter and 30 feet deep, pulverising all onboard. The depth of this gruesome tragedy was brought into sharp focus by the grieving, fuming relatives of the victims, parading the streets of Addis Ababa, carrying coffins. They were on their way to the local cemetery to perform the burial. And the coffins were all empty.
These crashes occurred within 18 months of introducing the new variant called Boeing 737 Max 8. After the very first crash, doubts were raised in aviation circles about the airworthiness of the aircraft. But Boeing maintained that their aircraft were safe. After the second crash, which was similar to the first crash, the FAA and Boeing were forced to ground the Boeing 737 Max 8 fleet globally. If Boeing had put safety before commercial interest, the second crash could have been avoided. Investigation revealed that the culprit in both the accidents was a software fix called M-CAS (pronounced as EMKYAS) that Boeing developed to counter the nose-up tendency exhibited by the aircraft at certain stages of flight.
What culminated in these two horrendous crash was the commercial interest and the trade rivalry between the two aerospace giants - Boeing Company and Airbus Industries. These tragic events had its genesis in the Airbus Industry’s announcement of their brand new aircraft, Airbus A320 NEO (New Engine Option), back in 2010. The delivery of the new plane was slated for 2016. What Airbus did was to fit a bigger, high-bypass, turbofan engine which increased the fuel-efficiency by 6%. The announcement came at a time when the airlines were reeling under rising fuel prices. As even 1% savings in fuel price would make a huge difference to the operating cost, airlines world over made a beeline to the Airbus to place orders. Even American Airlines, which usually rooted for Boeing, deserted them.
This caught the Boeing flat-footed. As the order book at the Airbus started filling up, there was panic in the Boeing camp. To catch up with Airbus they had to roll out a new aeroplane in about 6 years. Hence they could not afford the 10-year development cycle required for a newly designed aeroplane. So, they hastily decided to fit a bigger, fuel-efficient engine to the 50-year-old, thrice modified Boeing 737. A year later they announced the new Boeing 737 Max 8 aircraft, which would be delivered in 2017 with 8% more fuel efficiency. Also, as an incentive, they added that costly pilot training would not be required as the Aircraft Type Certification would not change. Later events would prove them wrong. They should have built a new aircraft instead of modifying a 50-year-old model.
However, this belated move paid off, and orders started pouring in boosting the profitability of Boeing and the shareholders. And the executives at Boeing received millions in bonus. But, during the design stage, a vexing problem surfaced. There was no sufficient ground clearance to fit a large engine under the wing of the Boeing 737. So the engine had to be raised and moved forward. That changed the aerodynamic characteristics causing the aircraft nose to go up especially during low-speed manual flying as in a takeoff. This would increase the Angle of Attack (AoA) to the point of stalling the plane. AoA is the angle between the aircraft wing and the relative airflow. If this angle increases above 15 degrees, the airflow over the wings becomes turbulent resulting in a stall. Unless the pilot takes timely recovery action, aircraft loses all lift and falls off the sky. Usually, the AoA will be around 15 degrees during takeoff.
To counteract this anomaly, Boeing designed a system that would automatically correct the nose-up tendency. They put a single AoA sensor outside the cockpit, which would send a signal to an onboard computer. The computer will command the electric horizontal stabiliser trim at the Tailplane, which controls the up and down movement (pitch) of the aircraft, to move the nose down. Simply put, the lift on the tailplane is increased to bring the nose down. Since this takes place automatically, the anomaly is corrected even before the pilot senses it. Here Boeing violated one of the sacrosanct doctrines in aircraft system design - Fail-Safe. This paradoxical term mandates that even if a critical system fails, the aircraft should still be safe. This is achieved by built-in redundancy - duplicating the critical systems. Here there was no redundancy; only one AoA sensor was installed.
And Boeing gave this hidden system a name which was completely shrouded in technical jargon - Manoeuvre Characteristics Augmentation System (M-CAS). It is nothing more than a simple Pitch Correction System over which the pilot has no control. In the case of autopilot, the pilot is in command. He flips a switch to operate it. Whereas MCAS is autonomous and the pilot is not in command. There is no switch to control it. However, there is a way to deactivate it - by switching off the electric horizontal stabiliser trim. But this was not known to the pilots or the airlines as the MCAS itself was kept in the dark. If the pilots were made aware of it, those 346 victims would be alive today.
Just after the takeoff phase of the flight, Boeing 737 Max 8 of the Lion Air was at 4000 feet. It was still climbing, when a faulty angle of attack signal made the MCAS operate the electric horizontal stabiliser trim to put the nose down. This uncommanded manoeuvre surprised the pilots. They reacted by operating the same trim to put the nose up. But the MCAS kicked in again to put the nose down. Again the pilots trimmed the nose up. This went on for more than 20 times The bewildered pilots did not know what was happening. They were wrestling with an unknown force to take back control of their aircraft. The aircraft was going into a nosedive, rapidly losing height and increasing speed. Now, the aerodynamic forces were so high that the aircraft stopped responding to pilots’ efforts to pull it out of the dive. Barely 10 minutes after takeoff, the aircraft dived at near supersonic speed into the Java sea. And the second crash in Ethiopia was a tragic copycat of the first crash, except that it only took 6 minutes to eternity.
Only after the second crash did Boeing admit to the existence of MCAS. To meet the delivery deadlines Boeing cut many corners and the regulator, the FAA, remained a mute spectator. Boeing pushed the certification procedure through the FAA using its enormous clout. Faced with a shortage of personnel and funding, FAA was happy to delegate most of the certification process to Boeing. And this suited perfectly well for Boeing. It enabled them to avoid the Aircraft Type Certification and to fulfil their promise to the Airlines to do away with costly pilot training. It was a serious mistake to entrust the very manufacturer with evaluating and certifying the safety of the aircraft they made.
Had the regulators been doing their job, they would have classified MCAS as a critical system which would call for redundancy - fitting multiple AoA sensors to enable the system to sanitize the input data to arrive at the correct decision. If notified, the existence of MCAS would betray the changed aerodynamic characteristics of 737 Max 8, warranting a change to the Aircraft Type Certification. This would result in production delays and necessitate pilot training. Inevitably, there would be a breach of promise Boeing made to the Airlines as a selling point. Thus Boeing was forced to commit the cardinal sin of hiding the MCAS. And it almost got away with it, because the regulator and the regulated were on the same page. So much for the much-flaunted infallibility of the American systems.
The crisis has the Boeing besieged from all sides. The very fact that the Boeing 737 Max remains grounded even after 13 months, shows there were serious safety aspects that were either hidden from the FAA or overlooked by them. Reeling under International criticism, the FAA launched a full evaluation of the aircraft. In June they found, among other things, a problem with the Flight control systems which has further delayed the aircraft's return to service. The Boeing has stopped the delivery of the new aircraft, and the Max 8 production line is stalled. The stock value of Boeing has plummeted by 25%. In the meantime, the relatives of the crash victims, the cash-strapped Airlines and the part suppliers are demanding compensation running into nearly $50 billion. If the Boeing Company were to make a brand new plane using the full development cycle of 10 years, it would not have cost them more than 6% of this. In the heat of the race to beat the Airbus, the company compromised the safety of the passengers and crew flying kilometres up in the air. For that unpardonable crime, they are now paying a very heavy price.
TailWind
A century ago William E. Boeing founded a company now known as the Boeing Company, which is an aerospace giant, manufacturing aeroplanes, helicopters, fighter jets, satellites and space vehicles. Enola Gay, which dropped the atom bomb, Little Boy, that vaporized Hiroshima in 1945, was a Boeing B-29 Superfortress bomber. It is on display at the Smithsonian National Air and Space Museum in Washington DC.
Sugathan R P
A Life Member of the Aeronautical Society of India, I was an aircraft engineer with the Naval Aviation and had served on board the Aircraft Carrier I N S Vikrant. Some of my articles were published in periodicals like CSI Communications and Meatball -a Naval Aviation Periodicals
