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Boeing jet’s autopilot appeared to cause aircraft to tilt down suddenly: pilot reports

Click to play video: 'Global fears grow over Boeing’s 737 MAX 8 planes'
Global fears grow over Boeing’s 737 MAX 8 planes
WATCH: Global fears grow over Boeing’s 737 MAX 8 planes – Mar 12, 2019

Airline pilots on at least two flights have reported that an automated system seemed to cause their Boeing planes to tilt down suddenly, the same problem suspected of contributing to a deadly crash in Indonesia.

The pilots said that soon after engaging the autopilot on Boeing 737 MAX 8 planes, the nose tilted down sharply. In both cases, they recovered quickly after disconnecting the autopilot.

The MAX 8 is the same plane at the center of a growing global ban by more than 40 countries following a second fatal crash, this time in Ethiopia, in less than five months. In the U.S., however, the Federal Aviation Administration and airlines continued to permit the planes to fly.

READ MORE: Air Canada flight attendants’ union says crew don’t want to be forced to fly on Boeing 737 MAX 8

American Airlines and Southwest Airlines operate the 737 MAX 8, and United Airlines flies a slightly larger version, the MAX 9. All three carriers vouched for the safety of MAX aircraft on Wednesday

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The pilot reports were filed last year in a data base compiled by NASA. They are voluntary safety reports and do not publicly reveal the names of pilots, the airlines or the location of the incidents.

It was unclear whether the accounts led to any actions by the FAA or the pilots’ airlines.

WATCH: Marc Garneau says Canada prepared to ground MAX 8 if need be

Click to play video: 'Marc Garneau: Canada prepared to ground MAX 8 if need be'
Marc Garneau: Canada prepared to ground MAX 8 if need be

In one report, an airline captain said that immediately after putting the plane on autopilot, the co-pilot called out “Descending,” followed by an audio cockpit warning, “Don’t sink, don’t sink!”

The captain immediately disconnected the autopilot and resumed climbing.

“With the concerns with the MAX 8 nose down stuff, we both thought it appropriate to bring it to your attention,” the captain wrote. “Best guess from me is airspeed fluctuation” due to a brief weather system overwhelming the plane’s automation.

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READ MORE: Boeing 737 MAX 8 bans — What Canadian travellers should know

On another flight, the co-pilot said that seconds after engaging the autopilot, the nose pitched downward and the plane began descending at 1,200 to 1,500 feet per minute. As in the other flight, the plane’s low-altitude-warning system issued an audio warning. The captain disconnected autopilot, and the plane began to climb.

The pilots talked it over later, “but can’t think of any reason the aircraft would pitch nose down so aggressively,” the co-pilot recounted.

WATCH: Pressure mounting for Boeing after deadly Ethiopian airlines crash

Click to play video: 'Pressure mounting for Boeing after deadly Ethiopian airlines crash'
Pressure mounting for Boeing after deadly Ethiopian airlines crash

Preliminary information released by Indonesian investigators suggests they are looking at the possible role of the MAX’s new automated anti-stall technology as a factor in a Lion Air crash in October shortly after takeoff from Jakarta. Data indicates that the pilots struggled with repeated nose-down commands from the plane before it crashed into the Java Sea and killed 189 people.

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READ MORE: Trump speaks with Boeing CEO, tweets that airplanes becoming ‘too complex to fly’

Concern about the MAX’s safety seemed to be abating but returned on Sunday when an Ethiopian Airlines MAX 8 crashed shortly after takeoff from Addis Ababa, killing all 157 people on board. Again, preliminary data appears to capture a brief and erratic flight. Investigators will analyze information from the planes so-called black boxes in hopes of understanding what caused the accident.

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