At least two US pilots had reported unexpected loss of height on the aircraft Boeing 737 Max – 13/03/2019

US airline pilots reported on at least two flights, an automatic system apparently rocked his Boeing 737 Max.

Captains stated that the incident had occurred shortly after turning on the autopilot and that the planes recovered quickly upon disconnection.

However, according to the pilots' description, the problem did not seem to be related to the new automatic anti-lock system, which was suspected to be one of the causes of the fatal crash in Indonesia in October.

More than 40 countries worldwide have banned the flight of the Boeing 737 Max 8 after a second fatal fall, this time in Ethiopia, less than five months after the first. However, US airlines and the US Federal Aviation Administration (FAA) did not adhere to the ban.

American Airlines and Southwest Airlines they operate the 737 Max 8, and United Airlines a slightly larger version, the Max 9. The three reacted for Max's safety Wednesday.

Pilot reports they were archived last year in a database of NASA. These are voluntary safety reports that do not publicly identify pilots, airlines or the location of incidents.

It is not clear whether the FAA or the airlines have taken action.

In a report, the captain stated that as soon as he had put the aircraft into autopilot, the co – pilot had exclaimed: "Descent". And then the cabin audio warned: "Do not go down, do not go down".

The captain disconnected the autopilot and resumed the climb.

"Concerned by the lowering of MAX 8 Horn, we both thought it wise to inform them about this," writes the captain. "My best guess is the fluctuation in airspeed due to a brief climate system to which the automatic systems of the aircraft could not respond."

On another flight, the co-pilot stated that a few seconds after turning on the autopilot, the trunk leaned forward abruptly and the plane began to descend at 365-460 meters per minute. As in the other flight, the audio system issued a warning. The pilot disconnected the autopilot and the aircraft resumed the ascent.

The pilots badyzed the situation later, "but I can not think of a reason for the nose of the plane to lean so aggressively"said the co-pilot.

Preliminary reports emanating from Indonesian researchers indicate that they are studying Max's new automatic anti-lock system as a possible factor in the crash of the plane. Lion Air shortly after taking off from Jakarta in October. The data indicates that the pilots they had problems with repeated orders from the plane to lower the trunk before falling into the Java Sea. In the accident, 189 people died.

But the anti-lock system – known by the acronym MCAS – is only activated if the autopilot is turned off, according to Boeing documents sent to the airlines and the FAA.

"I do not want to say that it's not a problem," said driver Dennis Tajer, of American Airlines, on incidents reported to NASA. "But it's not the MCAS, the autopilot has to be disconnected for the MCAS to be activated."

Another driver complains that Boeing had not explained the changes made to the automatic systems.

"I wonder what else I do not know?" Writes the pilot. "The flight manual is inadequate, almost criminal."

Source: AP.

LGP