A strange resemblance unites the recent crash of the Boeing 737 Max of Ethiopian airlines in Addis Ababa, and the incident, again of a 737 Max, of the Lion airlines, which occurred in October in Indonesia.
A New York Times report tries to clarify the causes and find a pattern that unites both tragedies. US and Canadian experts have recently revealed data on the two incidents, which occurred according to similar dynamics and thus questioning the real safety of these aircraft.
AUTOMATIC SYSTEM MALFUNCTION
The NYT reports the statements of Marc Garneau, Canadian Transport Minister, according to whom the records indicated “vertical variations” in the Ethiopian flight very similar to those already documented in the Lion Airlines crash.
Despite not having been made public, the data of the last incident and, consequently, not having been identified what caused it, some aviation experts, reports the NYT, say that based on the available documents it is probable cause of accident in both flights were the newly installed automatic system known as MCAS, whose function is to prevent the aircraft from stalling.
CHANGES IN ALTITUDE
In fact, it would seem that a malfunction of the sensors of this automatic system has caused in both cases the sudden lowering of the aircraft’s height, which the pilots tried to counter by taking manual control. In both flights, as evidenced by the data published by the NYT, from time to time there is a drop in altitude of 10-15 seconds, until the inevitable crash.
“The oscillation of about 15 to 20 seconds is a tell-tale signal suggesting the involvement of the MCAS system,” said R. John Hansman Jr., a professor of aeronautics and astronautics at the Massachusetts Institute of Technology.
In fact, planes such as the 737 oscillate naturally, for example due to a simple turbulence, but those particular oscillations, so regular, would signal the failure of that specific system which must, or should, prevent the aircraft from stalling and the consequent loss of altitude.
“From the available data there are similarities between the Lion Air case and the latter regarding the 15-second periodicity of those oscillations.”
That is, from time to time the plane stalled, and then down, for 15 seconds. Obviously, the expert concludes, we will know more when the data in the black box will be available. An obligatory prudence in the absence of more certain data.
CONSEQUENCES OF A FAILED INSPECTION
Don Thoma, CEO of Aireon, the company that provided the accident data, said the data “showed with certainty that there was something wrong with the plane, something they should have taken a look at”.
Apparently, this was not done. Thus, in just over five months, these aircraft on which so many questions are arising and now banned from the heavens by all the nations of the world, have caused more than 300 deaths. Pending answers, the perplexities for the previous inertia remain.