WHAT EXACTLY HAPPENED IN MAX-8 CRASHES - A Scenario

Updated April 6
In stunning news, the pilots of the Ethiopian Max DID shut off the MCAS.. and it didn't work - either the MCAS system software had priority over the other software that controlled the actual manual adjustments of the stabilizer, or the damned things weren't integrated and fought against each other. The MCAS only activated for 9 seconds, moving the stabilizer supposedly 2 1/2 degrees but I think it took many activations to move it the total amount, which was much more than the 5 degree maximum they claimed. The so-called manual trim wheel is a fine adjustment they would have had to spin it like mad to have an effect and it might not have been fast enough for them to realize it was working in their panic.
I hate these all computer control flight systems. I think there should always be a manual wire cable or hydraulic system that can be activated and the computer shut-off completely! Quite a few fly-by-wire F16s crashed before they were able to improve the software or systems but I'm not sure they ever figured out exactly why.


Mar 20:  The profile of the spanking new Max8 that crashed in Ethiopia (157 fatalities) is identical to the new Max8 Lion Air Indonesian crash (189 fatalities), a desperate fight for control with a killer computer right after takeoff.   LION AIR Max8-
Boeing's horrible new MCAS flight correction system created to compensate for the forward-moved heavier LEAP engines apparently can speciously decide you are about to stall and send the plane into a vertical dive! Without Trump packing the FAA with his hacks- FAA Acting Head Dan Elwell, an industry lobbyest, perhaps they would have grounded this new deadly model immediately. Instead, HE gets to be the hero, grounding the Max8's and Max9's, though that was really necessitated by Europe and esp Canada grounding them.  
      Ethiopian Max8 CrashSite                                                                                                

I've done a little private flying and ridden back seat at Embry Riddle (world's top aeronautical school in Daytona Beach) while hooded students practiced instrument stalls and extreme attitude recovery in little Cessna's: the correct procedure is point the nose down and increase power; the stall ends immediately (though they do it on the alarm). A stall comes from too slow a speed and too high angle of attack (too fast a climb)... the airflow is disrupted over the wing with complete loss of lift, an alarm goes off just before, and the plane just falls out of the sky!! On landing or low takeoff it is usually fatal. Even at altitude, if pilots don't respond properly, the plane continues to fall tail-first and can enter a deadly tailspin, very hard to recover from. But some pilots, losing altitude and attitude, instinctively pull the nose UP in a terminal mistake (not meaning they get to the terminal faster). It can also be caused by vicious turbulence or tailwinds or wind shear. But to a pilot there is simply nothing more terrifying than an automated system that is trying to fly the plane into the ground.

The root cause was the larger (1 ft dia) more powerful, heavier + efficient MAX LEAP1b engine needed increased ground clearance to avoid sucking up debris so they needed to extend the wheel struts, which they did with the nose wheel- 8". Apparently the middle wheels were more problematic- no space for longer ones (although maybe they could have gone with telescoping) so their FIX was moving the engines around (the heavier bigger engine already would change flight characteristics left in the same place), slightly forward and upward, which could pitch the nose up under certain conditions (because engines were higher + forward of midline?). There is nothing more crucial for any plane than the balance, and engine position is always a serious change, hence the lousy "band-aid" of MCAS, which they tragically then tried to keep quiet.

At a tense meeting with Boeing executives, pilots were furious at being kept on the dark:
"No, this plane is aerodynamically unstable as designed and MCAS is a bandaid meant to mitigate that fact. Boeing was too cheap to design a plane from scratch and so slapped these larger engines on an old design and fudged software to make it “ safe” to fly. Sorry, but this airframe was NOT designed to handle these engines, hence the tendency to pitch up."

Now the original short haul 737, the most popular by many-fold in the world, was SO improved that it's actually an Intercontinental jet with over 200 passengers and a 3800 mile range!  But it could pitch the nose up in some conditions, so the Maneuver Characteristics augmentation System (MCAS) was created to detect too steep a climb or extreme turn approaching a stall in manual flight and help the pilots by pushing the nose down, but Boeing apparently neglected to inform the pilots or put it in their Flight Crew Operations Manual, FCOM, to avoid “inundating average pilots with too much information"!
                             737 Max horizontal stabilizer in a pitch nose down config
The Elevator is the large horizontal flap that makes the plane climb or dive, the Trim Tab is a smaller fixed flap on the Elevator on a little plane, but apparently on the 737s the Trim adjusted the entire horizontal stabilizer (the whole horizontal tail) controlled by a large wheel in the middle of the console to make the plane fly straight and level. The actual Elevator flaps are smaller than the rest of the Horizontal Stabilizer surface!! 

 The MCAS system could apparently be triggered by only one of 2 angle of attack (AoA-Excellent piece!!) indicators on either side of the nose, one had just been replaced after the previous flight!! The 4 ft long jackscrew actually moving the Hor-Stab was found cranked to the end (nose down) in the Ethiopian wreckage!! Tragically, pilots could have disabled the errant MCAS system by shutting off the automatic trim system (fine elevator pitch adjustment) system... just by flipping a toggle switch- in all honesty, they obviously SHOULD have done this, confronted with such wild control overrides, especially the Ethiopians, after reading about the first crash and the Boeing adviso!

Adjusting trim by any of 3 means would shut down the 9.3 second MCAS adjustments, but it would reactivate in 5 seconds if it still was detecting a near stall. Horrifically the 9 second MCAS trim adjustments were cumulative, 2.5 degrees each*, more and more, till by the end the aircraft was uncontrollable; in the LION AIR crash it was activated 21 times- 4 minutes of pushing the nose down more and more! The pilots desperately ran through checklists to try to regain control... and a flight crew the day before did the same thing- an extra deadheading pilot saved them in shutting off the auto-trim system, so did the 2 previous flights!!!   What, no aircraft LOG- of course they notified the airline, who criminally failed to notify the NEXT CREW!!!  The Jan Boeing ordered software update was allegedly delayed by 35 days due to the Trump Wall Government shutdown, but that is dubious since it's still slated for April.
* 4 times more than the 0.6 degrees in Boeing certification documents; SeaTimes claims 2 activations- 5 degrees is the Max, but there is evidence to the  contrary
- TRIM Controls on the Boeing 737 Max 9 (fine elevator pitch adjustment)

WIRED -"The problem with the Lion Air flight was the MCAS went to work when it shouldn’t have. The 737 MAX was climbing normally, but due to a faulty sensor the digital flight data recorder detected a hard-to-believe 20-degree difference in the angle of attack between the left and right sides  (MH- even on the ground!, meaning plane was in a steep turn or weird tilt, another risk for a stall). Over the next 10 minutes, the pilots repeatedly tried to pull the plane’s nose back up, but the MCAS kept forcing the yoke forward, pushing the plane down. Ultimately, the plane crashed into the Java Sea, killing everyone aboard."

But there were other problems with the flight control system, pilots bitterly complained 5 times in recent months, the Auto-Pilot was squirrely and undependable, sometimes pitching the nose down till it was disengaged, and the Autothrottle would throttle back unexpectedly (that could cause a stall or stall warning too!). NOTE, the MCAS was engaged ONLY in MANUAL flight (not AutoPilot), so these are 3 distinct serious problems in 3 different systems, 4 with the problem below!!

AHA, the competition to beat the Airbus320 Neo!! That's where this nightmare stems from: Boeing simply wanted to speed up the process so they EGREGIOUSLY LIED in saying the completely redesigned MAX plane with spanking new repositioned bigger, quieter, more efficient engines; split winglets, longer nosegear, extended cabin, redesigned computer flight control systems, and significantly altered handling characteristics... was substantially THE SAME as the older version, so expensive pilot simulator retraining was not necessary, just a documents refresher. NO IT WASN'T + Yes it was!  
 
Imagine this scenario, which may not be far from the reality, since the Lion Air Max 8 had problems with the airspeed indicator on 4 previous flights! (confused with AoA problems?)

A. Bam, a starling slams into the pitot tube, the air speed indicator tube, partially blocking it.

B. Real airspeed is now 350 mph 6 min after takeoff, but plane is still in a relatively steep climb at 2 miles alt to make it to thin air cruising altitude at 30-36K ft [planes climb much too steeply on takeoff because of airport noise constraints]; but INSTRUMENT airspeed is only 150 mph and computer freaks out... to it the plane is seconds from a full stall (and a powered one is more violent)

C. Helpful MCAS system, which they didn't inform pilots of, pushes the nose down. Pilot has no idea what's going on, everything is fine, maybe he hasn't noticed whacked airspeed, fights the system, pulling nose up. Computer sees attempted angle of attack INCREASING, goes into next stage of emergency, pushes nose down more. Pilot, freaking out, in the dark, pulls nose up again harder.   Ethiopian Max8 before

D. Stall alarm goes off, based on incorrect airspeed as mashed bird blocks pitot more, but plane has accelerated, barreling towards the ground (only ~5000 ft below) at 450 mph, or now 15 seconds away at 45 degrees down!! Pilot is now desperately hauling up on the stick (wheel), but computer is smoothly compensating to save the stupid human from his reckless panic.

E. Plane smashes into the ground at 550 mph near vertically, atomizing everything, even the microorganisms.

Indeed, all the Ethiopian Gov could give to victim relatives was handfuls of charred earth!
                                  Lion Max8 After

All that said, Boeing is one of the Great Companies of the World- their 747-787 assembly building in Everett is awesome, biggest in the world, 2.5x the size of NASA's Vehicle Assembly Bldg, with 3-4 of the immense planes under construction at once! The International Airport in central Seattle (after they built SeaTac south of the city) became Boeing Field for their sporadic tests, and a paradise playground for private pilots, with the best Flying Club in the country. The Everett/Boeing Air Show is probably the best in the country, I would go up and camp there for 2-3 days viewing every imaginable aircraft (like the Stealth bomber), In one Press flight at Boeing Field I got to waddle an all-glass Scout helicopter over I5, my mental visualizations of controlling a dragonfly tail by rudder pedals after reading a helicopter flight manual worked!

 Currently 376 MAX 8 + 9 models (also have 7 + 10) have been delivered, but Boeing has over 5000 orders of the hot new plane, which has made hundreds of thousands of successful flights and is normally a joy to fly. Ironically, properly warned with the way to disable the MCAS system, that threat is past!! (Addendum: But not the other dangerous computer glitches). I hope this stupid and inexcusable screw-up doesn't permanently damage the company, which is the single greatest US Exporter by far, and the world's largest aircraft manufacturer,

- Boeing 737 Max8 Plant- Renton WA