Countries Restricting 737 MAX Flights After Second Crash

[Chance]

From Dallas Morning News:

The United States will issue an 'emergency order' grounding all Boeing 737 Max 8 and Max 9 aircraft following the Ethiopian Airlines crash that killed 157 people.

At the White House, President Donald Trump said the planes will be grounded "until further notice... The safety of the American people, of all people, is our paramount concern."

Any plane currently in the air will go to its destination and then be grounded, the president said.

The president's announcement stands in stark contrast to statements from top federal regulators this week who, along with airlines, have said they are confident in the aircraft's safety and airworthiness.

The FAA said the decision came as a result of its data gathering process and new evidence collected at the site of the crash and analyzed Wednesday.

[hufnagel]

Not sure if...
knee jerk
over-reaction
someone connected shorted a shitload of Boeing stock recently

[Stephanie B]

Not sure if...
knee jerk
over-reaction
someone connected shorted a shitload of Boeing stock recently

Knee jerk from the Biggest Jerk.

IMNSHO

[Rex G]

Well, the historian side of me recalls what happened to De Havilland, after the incidents with the Comet, in the Fifties. In the end, if there are one or two more crashes, and/or if enough folks will simply not fly on 737 MAX planes, there could be an extinction event.

To be clear, this post is not a direct response to any specific post in this thread.

[GJM]

If this new model 737 can only be safely flown by highly skilled US flight crews, with many logbooks full of stick and rudder skills, when previous generations of the 737 could be reasonably safely flown by most third world flight crews, with only the typical CFIT, runway overrun and loss of control accidents in monsoon conditions, something is wrong with Boeing’s new design. No doubt it will be fixed soon.

[Drang]

Knee jerk from the Biggest Jerk.

IMNSHO

Thank you for the very helpful contribution to the technical discussion.

According to CNN:

Trump said the decision to ground the Max 8 and Max 9 was made in light of new information about last week's crash, which killed 157 people. The Federal Aviation Administration said new evidence had been collected at the sight of the crash on Wednesday, and that information -- along with new satellite data -- led to the grounding decision.

[MistWolf]

Two days ago the FAA issued a Continued Airworthiness Notification for the 737 MAX. Yesterday, they stated the MAX was still good-

3/12/19 6:10pm Update

Statement from Acting FAA Administrator Daniel K. Elwell

The FAA continues to review extensively all available data and aggregate safety performance from operators and pilots of the Boeing 737 MAX. Thus far, our review shows no systemic performance issues and provides no basis to order grounding the aircraft. Nor have other civil aviation authorities provided data to us that would warrant action. In the course of our urgent review of data on the Ethiopian Airlines Flight 302 crash, if any issues affecting the continued airworthiness of the aircraft are identified, the FAA will take immediate and appropriate action.

That seems to have changed today-

3/13/19 3:00pm Update

Statement from the FAA on Ethiopian Airlines

The FAA is ordering the temporary grounding of Boeing 737 MAX aircraft (PDF) operated by U.S. airlines or in U.S. territory. The agency made this decision as a result of the data gathering process and new evidence collected at the site and analyzed today. This evidence, together with newly refined satellite data available to FAA this morning, led to this decision.

The grounding will remain in effect pending further investigation, including examination of information from the aircraft’s flight data recorders and cockpit voice recorders. An FAA team is in Ethiopia assisting the NTSB as parties to the investigation of the Flight 302 accident. The agency will continue to investigate.

Link to the Emergency Order of Prohibition (pdf)- https://www.faa.gov/news/updates/med...ency_Order.pdf

[Suvorov]

Really interesting stuff to read from the airline guys here.

Question for you commercial guys.....I only ever flew single engine props. In a 152 or Cherokee, you could be near unconscious and you'd still get enough feedback from the platform to wake you up prior to stalling.

With these big busses, what is the significance of the built in stall protection? Why is this so important? Is there simply not enough feedback with an airliner to detect an impending stall?

Ray already handled it pretty well - and his experience is seat of the pants while mine is only theoretical (and I'll be happy if it remains so). I have flown two different transport category airplane types (airliners) in my career - the Embraer 145 and the 737. I have been able to do "Extended Envelope" training on both which mean taking the simulator to a full stall. For many years simulators were not able to replicated the actual flight dynamics of the airplanes stalls and the violent movement would place extra wear and tear on the sim - so this was not trained. After the Colgan and Air France crashes the FAA mandated improved stall training for airline pilots. Where as before the stalls maneuvers would be taken only to initial indications (buffet or shaker) - in the Extended Envelope training the stalls are taken to full stall. The FAA also redesigned the stall profiles to make the training much more relevant. While EET was not mandated while I was flying the Embraer, I received it when I was chosen to be a flight instructor on the jet.

As Ray mentioned there is a pronounced buffet in the 737 prior to the stall and that is quickly accompanied by the "stick shaker" that causes the yoke to vibrate. This would be the normal indications for the pilot to recover from the stall by pushing the nose forward and adding power as needed (however in an airplane like the 737 this can actually aggravate stall recovery - more on that with MCAS). Failure to recover will cause the airplane to quite literally drop out of the sky. It will take hundreds to thousands of feet (dependent on altitude and how well executed the recovery was) before the airplane gets flying again.

With big airplanes (including "little Regional aircraft") there are a couple things making stalls a bigger deal than in your Cessna 172. First is that they have much more mass - that means that once they get falling, they need more time to stop falling. Second is that their jet engines have slower "spool up" times than a piston aircraft meaning that the thrust to "power out" of a stall may not be available for 5 or more seconds (or may not be available at all at higher altitudes). Third is that these aircraft usually have swept back wings which tends to cause one wing to loose lift before the other one resulting in the airplane rolling violently to one side and making stall recovery more difficult. Forth is that transport category aircraft are only built to handle load-factors (G's) of 2.5. This means that they are easier to over-stress during recovery than a Normal Category Cessna (3.8G) or Utility Category Cessna (4.4G). During recovery great care must be taken to not over-stress the airframe and that means slower recovery. Fifth is that these airplanes usually fly in the flight levels where the air is thin, and the engines are producing a fraction of the thrust they do at sea level. While a full stall at 5000 feet can be recovered from fairly quickly a full stall at 38000 feet may take 5000 feet or more to recover from. Lastly of course is the fact that you have passengers and crew who may be up and about in the cabin that will get thrown about and hurt.

As for the ERJ - it has a "T" tail and as a result it's tail does not experience much of the turbulent air flowing off the wings prior to a stall that creates the "Buffet." It also has a very reliable habit of dropping a wing and rolling off in a stall. As a result that airplane is built with not only a "stick shaker" but also a "stick pusher" which shoves the nose of the airplane down just prior to full stall. Probably shouldn't say this but I know of at least one incident at my former employer where the crew and passengers were quite possibly saved by the pusher.

Finally a bit about MCAS and this ties into adding power during stall recovery in an airplane like the 737. Airplanes like the 737, 757, A320, 777 all have powerful "low slung" engines. When power is added there is a nose up moment that causes the airplane to want to pitch up. While this can be helpful it can also place the airplane in a dangerously nose high situation that could induce a stall. This has been a contributing factor to many accidents and near accidents, especially during missed approaches and go-arounds. This To counter this all 737 airplanes have a "Speed Trim" system that will command nose down trim for certain thrust/airspeed/pitch parameters so that the yoke has closer to a normal feel and control is easier to maintain. Because the Max has even bigger and lower mounted engines the Boeing Engineers decided they needed to add a second system to protect the airplane in high pitch/low airspeed/high thrust situations - thus they developed the Maneuver Characteristics Augmentation System. MCAS works very much like the "Speed Trim" system but has slightly tighter parameters and receives input from some different sources (Angle of Attack vanes). All Pitch Trim systems can be deactivated though a pair of switch on the Throttle Stand. In the Lion Air accident the crew never did deactivate the trim through these switches.

One last bit is the fact that Boeing did not exactly advertise the existence of the MCAS system. None of my original manuals or training I received before flying the Max mentioned it. Boeing has been criticized for this but to my knowledge has taken the position that a) the information was in the tech manuals and was the fault of the airlines for not telling the crews about it and b) that regardless, an MCAS malfunction is no different than any other pitch trim malfunction and there is already a standardized procedure for handling such situations. I personally disagree with them on the first point but concede the second point.

Sorry kind of got long winded here.

[the Schwartz]

Knee jerk from the Biggest Jerk.

IMNSHO

Thank you for the very helpful contribution to the technical discussion.

According to CNN:Trump said the decision to ground the Max 8 and Max 9 was made in light of new information about last week's crash, which killed 157 people. The Federal Aviation Administration said new evidence had been collected at the sight of the crash on Wednesday, and that information -- along with new satellite data -- led to the grounding decision.

Even when President Trump takes preventative/cautionary measures to ground an aircraft that might, just possibly, fail and result in the death of those aboard, he's a jerk. What a ''big meanie''. Perhaps the Democrats can launch a probe of that, too.

I, for one, am grateful that President Trump did so since I have some air travel in my immediate future (an 'out-of-town' consultation for a wonderful client) and would just as soon have the software issues (if they exist) sorted out before someone, including 'yours truly', gets hurt or dies. It might also be a training issue (or pilot error), but this action (also taken by other countries leaders whom I assume, must also be jerks) is the most prudent one; human life is precious and I would not want to see anymore tragedy visited upon others if it can be avoided.

[the Schwartz]

Airplanes like the 737, 757, A320, 777 all have powerful "low slung" engines. When power is added there is a nose up moment that causes the airplane to want to pitch up. While this can be helpful it can also place the airplane in a dangerously nose high situation that could induce a stall.

Is it that resultant upward attitude (pitch) that causes the empennage to encounter the exhaust effluent (and its turbulent effects) causing loss of rear surface control?