The fatal crash of an Ethiopian Airlines aircraft leaving Addis Ababa on Sunday (Mar 10), with the loss of 157 lives, follows a downing of a Lion Air flight off Indonesia in October, with 189 lives lost.
Boeing's advanced version of their successful 737 series variant, 737 Max, is one of the top charter and a big rival for Airbus's A320 Neo. 737 Max 8 is widely used by many airlines around the world, and Jet Airways being the first airline to launch 737 Max8 in India, followed by Spice Jet. Recently, India's DGCA had ordered both SpiceJet and Jet Airways to ground their 737Max fleet with immediate effect. Many countries including China , European Union, UK had also asked their airlines to ground or temporarily suspend all 737Max8 fleet operation.
But Boeing assures that the matter is being investigated and US FAA asked Boeing to take necessary steps and corrective measures; also assured that the 737 max family is still airworthy and doesn't need to be grounded. On this view, American operators are still using their 737max fleet for operation.
Press release from Boeing :-
A pitch augmentation control law (MCAS) was implemented on the 737 MAX to improve aircraft handling characteristics and decrease pitch-up tendency at elevated angles of attack. It was put through flight testing as part of the certification process prior to the airplane entering service. MCAS does not control the airplane in normal flight; it improves the behavior of the airplane in a non-normal part of the operating envelope.
Boeing’s 737 MAX Flight Crew Operations Manual (FCOM) already outlines an existing procedure to safely handle the unlikely event of erroneous data coming from an angle of attack (AOA) sensor. The pilot will always be able to override the flight control law using electric trim or manual trim. In addition, it can be controlled through the use of the existing runaway stabilizer procedure as reinforced in the Operations Manual Bulletin (OMB) issued on Nov. 6, 2018.
The first fatal accident involving Boeing's 737max8 series was the crash of Lion Air flight 610 which was enroute to Pangkal Pinang from Jakarta on October 29, 2018 killing all the passengers and crew onboard. From preliminary reports, Boeing warned all 737max8 operators to avoid causing an abrubt dive. Boeing , the airframe manufacturer, GE Aviation the engine manufacturer, along with US FAA and NTSB joined investigation team for support. Australian Transport Safety Bureau also joined for decoding FDRs.
Priliminary investigation revealed both Lion Air and Ethiopian Airlines flights experienced similarly erratic steep climbs and descents and fluctuating airspeeds before crashing shortly after takeoff. Report of aircrafts last flight before the fatal flight 610 revealed that the aircraft had suffered serious incident. Loss of altitude was noted and air traffic control recordings revealed that the pilot had called a "PAN-PAN", which is second highest alert level below "MAYDAY" call. Aircrafts maintenance logbook revealed, during that flight , the flight had suffered an unspecified navigation failure on captain's side but no such errors on First-Officers side. Then the engineering team had made inspection and cleared for the fatal flight 610. Since both the flights reported to have steep climb and descents with varying or fluctuating airspeed, shortly after takeoff, there can be a common cause for both accidents.
Talking about the 737 max series, they are powered by Fly-By-Wire system, which is an advanced technology where the computer plays a major role in supporting flight crew. This can help the crew to maneuver the plane easily and can alert the crew well in advance.According to FAA, Autopilot system is used for 90% of the journey starting from shortly after takeoff till landing procedure. But everything has some drawbacks. In this case, a faulty sensor can even put a whole plane down. The faulty sensors onboard Lion Air made a confusion to onboard system which made it think that flight is going to stall, but actually it wasn't. Angle of attack sensors on the aircraft tell the MCAS to automatically point the nose of the plane down if it is in danger of going into a stall. Boeing is working to find the exact cause for this malfunction and will soon be rolling out software updates to ensure safe flights.
Going back to the question... Is B737 max series safe to fly? Answer can be complicated and will be revealed after the investigations of Lion and Ethiopian Air Crashes. Hundreds of B737 max series aircrafts are flying around the globe without major incidents, but two fatal crashes with a short gap of 05 months had raised the question of its airworthiness. Investigations will reveal the exact reasons for crashes.
FAA : Federal Aviation Administration
NTSB : National Transport Safety Board
DGCA : Directorate General of Civil Aviation
OMB : Operations Manual Bulletin
FCOM : Flight Crew Operation Manual
MCAS : Maneuvering Characteristics Augmentation System
FDR : Flight Data Recorder
AOA : Angle of Attack
Images : Google , jetphotos
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