Two deadly crashes in a span of less than five months involving one of the most modern aircraft in the market, the Boeing 737 MAX 8, have prompted aviation authorities and airlines to draw similarities between the two incidents. On October 29 last year, shortly after takeoff from Jakarta, a MAX 8 operated by Lion Air went down into the Java Sea after loss of control. On Sunday, a Nairobi-bound jet of the same make operated by Ethiopian Airlines crashed minutes after it had become airborne in Addis Ababa. A total of 346 people were killed in the two accidents.
Why has there been a global panic reaction to the Ethiopian Airlines crash?
While even a preliminary cause for the plane going down in Addis Ababa is yet to be ascertained, the events preceding the crash of another aircraft of the same model have raised the red flag. To begin with, both airliners went down minutes after takeoff. In both cases, the pilots are reported to have requested a return to the airport after takeoff, suggesting problems with control. Even as both accidents are being investigated, these similarities have made airlines and regulators cautious. Authorities in China and Indonesia have asked local airlines there to ground Boeing 737 MAX 8 aircraft as a precaution and to ensure their airworthiness. The aircraft, the latest in line of Boeing’s 737 family, is being considered by major 737 operators as a replacement model for the hundreds of 737 NG that are in operation today. Boeing has delivered 350 737 MAX aircraft so far, according to information on its website.
What is the problem with Boeing 737 MAX?
The latest Boeing 737 model, it is equipped with a manoeuvring characteristics augmentation system (MCAS), which is responsible for pushing the aircraft’s nose down when it senses a high angle of attack that may lead to an aircraft stall. If an aircraft’s nose is too high, the plane loses speed and is likely to enter a stall — a state in which it loses flight and can fall from the sky like a stone. The MCAS was designed to prevent such an eventuality. However, in the case of the Lion Air aircraft, the flight preceding the one that crashed experienced certain problems in the angle-of-attack sensor installed on the aircraft, which led to the MCAS falsely believing that the plane was about to enter a stall. A report issued by Indonesia’s air accident investigator documented that the maintenance logs for the accident aircraft recorded problems related to airspeed and altitude on each of the four flights that occurred over the three days prior to the fatal flight. On those flights, the pilot was able to recover. However, the next flight on that aircraft could not be recovered.
The Ethiopian plane had flown for only 1,400 hours before it crashed, and Ethiopian Airlines is believed to have a good safety record. In both the Lion Air and Ethiopian Airlines cases, the pilots tried to return to the airport a few minutes after takeoff but were not able to make it back. And both flights experienced drastic fluctuations in vertical speed during ascent. As per aviation safety experts, an aircraft should not record negative vertical speeds during the initial ascent. It is only when the aircraft is about to reach its destination and departs from cruising altitude that negative vertical speeds are meant to be recorded. Both the Lion Air and Ethiopian Airlines planes recorded unstable vertical speeds, according to data sourced from Flightradar24.
In India, two airlines, SpiceJet and Jet Airways, operate a total of 17 737 MAX planes. After the Lion Air incident, the Directorate General of Civil Aviation (DGCA) instituted a daily reporting mechanism from both airlines, and “no significant concern” was observed. After the latest crash, while India has not grounded the aircraft, the DGCA issued additional safety instructions Monday to both airlines for operations of these aircraft. As per the DGCA, engineers and maintenance personnel looking after the aircraft have been instructed to factor in additional checks, particularly those pertaining to the jet’s autopilot and stall management systems. The airlines must also ensure that crew members operating the 737 MAX have undergone training as per updated guidelines issued by DGCA on December 3, following the Lion Air accident. It has also said that the pilot commanding the aircraft should have at least 1,000 hours of flying experience on the Boeing 737 NG aircraft type, and the co-pilot at least 500 hours.
Has there been a blanket grounding of a fleet worldwide when there were problems with any aircraft model?
In cases where there are incidents that highlight safety concerns with an aircraft, the manufacturer and the regulatory authority of the country that approved production of the aircraft model take a call on grounding of the planes. In case of the US, its regulator Federal Aviation Administration (FAA) had, in 2013, announced grounding of Boeing 787 Dreamliner aircraft – launched that year – following heating problems with lithium ion batteries in the plane that caused the battery to catch fire. The FAA grounding had followed voluntary groundings by Japan’s All Nippon Airways and Japan Airlines, which were among the early buyers of the model. Following the crash in Addis Ababa, Ethiopian Airlines, too, voluntarily grounded its entire fleet of 737 MAX aircraft, and the move was followed by Cayman Air and Morocco’s Royal Air Maroc.