Pilots have reported issues in US with new Boeing jet

Pilots have reported issues in US with new Boeing jet
In this photo taken Monday, March 11, 2019, a Boeing 737 MAX 8 airplane being built for TUI Group sits parked in the background at right at Boeing Co.'s Renton Assembly Plant in Renton, Wash. Britain, France and Germany on Tuesday joined a rapidly growing number of countries grounding the new Boeing plane involved in the Ethiopian Airlines disaster or turning it back from their airspace, while investigators in Ethiopia looked for parallels with a similar crash just five months ago. (AP Photo/Ted S. Warren)

Airline pilots on at least two U.S. flights have reported that an automated system seemed to cause their Boeing 737 Max planes to tilt down suddenly.  

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.

As described by the pilots, however, the problem did not appear related to a new automated anti-stall system that is suspected of contributing to a deadly October crash in Indonesia.

The Max 8 is 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.

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

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.

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.

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 (365 to 460 meters) 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.

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.

However, that anti-stall system—called MCAS for its acronym—only activates if the autopilot is turned off, according to documents Boeing has shared with airlines and the FAA.

"That's not to say it's not a problem," American Airlines pilot Dennis Tajer said of the incidents reported to NASA, "but it is not the MCAS. The has to be off for MCAS to kick in."

A third pilot complained that Boeing had not explained changes to the 's automation to pilots.

"I am left to wonder: what else don't I know?" the wrote. "The Flight Manual is inadequate and almost criminally insufficient."

The FAA declined to comment on the incidents that pilots reported, but said it was not aware of any verified reports of MCAS-related issues in the U.S.

American Airlines spokesman Ross Feinstein said the airline has received no reports from pilots about problems with the anti-stall technology. Southwest has said the same thing.

Leaders of the union representing United Airlines pilots, some of whom have flown the airline's 14 Boeing 737 Max 9 jets since last May, said the airline has tracked 23,000 hours of flights and found no performance or mechanical problems.

The group, part of the Air Line Pilots Association, added, "It is imperative that pilots refrain from interacting with the media and adding to the sensationalism surrounding these incidents."

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.

Explore further

Ethiopian Airlines crash: What is the MCAS system on the Boeing 737 Max 8?

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Mar 13, 2019
This looks like the avionics software and instrumentation people will need to be called in to make sense of the black box data on the downed flights.
It all seems to be related to the pitch of the aircraft: The pitch moment/torque of the unusual forward-offset-mounted engines and the correcting tweaks to both the autopilot and MCAS systems??
The relative rarity of issues suggests an unanticipated faulty instrument input is the trigger of a badly coded automation response. Or it could be something as simple as a badly designed 'improved' angle-of-attack sensor on the new planes.

Mar 13, 2019

So the Americans are going to learn the hard way
having the auto pilot unable to properly distinguish an aeroplane
near its stall speed and stall angle on take off
a recipe for disaster
only feet from the runway with no wiggle room
but for these quick thinking pilots
they switched the autopilot off
these pilots
thank their lucky stars
has not got round to taking that critical decision out of these pilots hands
otherwise, America has to our knowledge
had three incidents
of the autopilot
thinking the plane was stalling on take of
The mind boggles when Boeing goes completely Auto!

In memory of these lost souls
Nancy Sinatra in You Only Live Twice

Mar 13, 2019
The issue of the behavior of the Boeing 737 invokes a crucial question no one seems to ask.
How do the manufacturers know their planes are safe?
For most manufacturing, safety is determined by actual, real time, physical tests. Do the manufacturers of commercial jets have a place they use to test the behavior of their planes? Is there some kind of proving ground where tests are performed to see how they act? It seems, if there were,it would be profiled regularly in magazines, on news programs. The sight of huge jets being put through paces would be something a lot of people would be interested in seeing.
Since they never show this, it is reasonable to assume none of the companies has such a program. They apparently send all the jets out without any real testing and let the people be Guinea pigs.

Mar 13, 2019
I'm sure the manufacturers flight test their new planes; to the extent they are legally required to. Including the extremes of the flight envelope on an A1 condition test plane at safe altitudes with one engine shut down.
I'm sure they also do some further testing to avoid expensive mass recalls.
Its then cheaper to hire lawyers than undergo extensive fault condition testing.
I've not heard of any test flying with faulty flight sensors, or predictable plane-specific pilot errors; see lawyers if you claim the planes are not airworthy.
The accountants and lawyers have full confidence in the safety of their planes.
(The statistics do agree they are mostly safe. Anyone volunteering to be a statistic?)

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