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24 June 2019


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Bill H

My wife flies Southwest routinely. If the flight she is on shows up to be a 737MAX, she will not get on it, and if Southwest gives her a hard time about that they will lose a regular customer. Neither of us cares what claims Southwest or Boeing makes for a badly designed airplane which is flyable only due to fast track designed computer software.

ex-PFC Chuck

In response to word that Boeing may consider renaming the 737MAX some wag on Twitter came up with a suggestion that is compatible with the company's branding policy: 737 FlatLiner.


The IAG order seems to be for deliveries of the 737 MAX 8 and 9 in 2023 and beyond so a reasonable period to get it sorted.

Also no doubt brilliant negotiating by Willie Walsh hitting Boeing at a most vulnerable time when it really needed a vote of confidence like that. As you suggest I suspect the price was eye watering for Boeing but it got them the biggest order of the Show.


The IAG has so far been an Airbus customer. Airbus was not asked for a bid but will surely make a counter offer. Boeing only has a MoU so far. We'll see if that converts to fixed orders.

The FlatLiner will most likely take until December to be allowed back into the air.

There is still the problem with the manual trim wheel which does not work in some situations where it is needed. At least some regulators are bitching about that. All Boeing NG have by the way the same problem. If regulators would go by the letter those thousands of 737NG would all be grounded.

As the Wall Street Journal reported last week: Boeing’s Latest 737 MAX Concern: Pilots’ Physical Strength
Turning manual crank during emergency procedure may be too difficult for some people

I explained the history of that problem and the technical details several weeks earlier: Boeing 737 MAX Crash Reveals Severe Problem With Older Boeing 737 NGs

The 777x also has an additional problem with its foldable wingtips. The FAA recently demanded additions to their status signals in the cockpit.


IAG will have got those B737 max at an absolute bargain price.


I wonder if Airbus were glad Boeing got that large commitment - no point being part of a duopoly if your partner crashes and burns.


One large point is service after sale. Boeing is making a dedicated, sustained push to expand its MRO business. They also have an enormously efficient production process. They may make far money on sustaining the jets than producing them.


If I have this correctly, the manual trim wheel is a left over from the 1967 design process. The actual trim system, the one MCAS took over, is the powerful electric motor/screwjack system that moves both horizontal stabilizers in order to set pitch. In manual mode the pilots control that system with a thumb switch on the yoke.

In an A320, there is a similar primary trim system, but no back up manual trim system because, unlike the boosted cable controls of the 737, it is fly by wire. So the 737 can be considered to have an extra margin of safety that its Airbus counterparts do not have.


You have got that a bit wrong.

In the event of a MCAS incident or a "runaway stabilizer" the procedure calls for cutting all electricity to the single stabilizer motor. After that there is no longer a thumb switch available.

The pilots then need to trim with the manual wheel which is evidently impossible in some speed and stabilizer position ranges. (On why that is so read my piece.)

The manual trim wheel is not a "left over" but its function is a critical regulation requirement for all 737.

The A-320 has 4 times redundancy for moving critical flight surfaces. The extra margin of safety is clearly on its side.

SAC Brat

Airbus Single Aisle aircraft (A318/319/320/321s) have manual trim wheels on the pedestal next to the throttle levers. These can be used for manually setting trim position or stopping run-away trim.


Starting with the 777 Boeing added flight envelope protection to its aircraft that trimmed nose down. After years of Boeing fans complaining about Airbus design philosophy it was fun to point out the same concept becoming standard on Boeings. Most of these implementations could be overpowered by the pilot while primary or standby trim was being switched off.

SAC Brat

It would be nice if Boeing remembered they were trying to improve customer service and product support. They have slipped into the Comcast/AT+T/Honeywell model. It also doesn't help that many American companies like to change org charts every thirty days and the operators have to teach the company reps the history of their product.


The 737 has steel cables which connect the trim wheels to the stabilizer jackscrew. Airbus are fly-by-wire and do not have these.

Those wheels in the A320 are as much "manual" as a light switch. They are moved by a motor in normal mode. In "direct law" mode (after normal and alternative law mode failed) the pilot moves them which gives signals to an electric/hydraulic system to move the stabilizer.

SAC Brat

I am a working girl not an anorak. Try doing some reading on A320 family control cables. May I suggest:


If you can't research a defined subject like an aircraft what is the quality of your other research?


Does anyone know if the MAX8 had a MCAS circuit breaker or even an isolator to enable it to be depowered in the event of a runaway ? It would appear that a runaway occurred the day prior to one of the accidents, but was stopped by a supernumerary pilot in the jump seat, and this would suggest it was possible to trip the thing off line.
Runaway electric trims have been around as long as electric trims. Either through company Phase One training (of immediate memory actions) or bitter experience, pilots learn to locate and depower the breaker, be it Trims, AP or Yaw Damper, in the blink of an eye.
Well, most pilots do; perhaps not so in the cases of the two accident flights.

It is a common thing for both a manufacturer's and company checklist to not contain critical lines, which are then not trained for, leaving the crew to rely on past experience or systems knowledge to find a solution for which time may not allow.


As MCAS is software, I don't believe there is a way to switch it off. The option is to turn the electric motor off on the screwjack mechanism in the stabilizer system. Then you have to trim the horizontal stabilizer by hand using the manual trim system.


Thanks BF, it would be good to see a copy of the relevant aircraft Quick Reference Checklist, either OEM or company's, and a pic of the panel. Yes, manually retrim while opposing the uncommanded pitch with stick force, and the FAR design requirements dictate that it all be physically possible to do for the average pilot.

I sincerely hope that a c/b or isolator is fitted if not already present.

Runaway Flap is another story...


The recent House Aviation Subcommittee hearing was informative and less than reassuring. This included representatives of pilots, attendants, FAA, and Sullenberger.


Carey,representing pilots, and Nelson, for crews, make telling points and raise critical questions.

Sullenberger emphasized flaws in the aircraft design, certification, and training process that compromise safety, beyond just the flaws of the MCAS in the MAX. He, also, raises a different safety issue on the MAX, related to landing gear. I had the impression that Sullenberger doesn't like much about the MAX.

Among process flaws, both Sullenberger and Babbit (FAA) cite inadequate pilot training and information about equipment. Sullenberger also mentions the difficulty of FAA oversight of overseas maintenance. Sullenberger emphasizes that software design must consider the "human interface," and what a pilot can reasonably manage. Ultimately, he indicates governance as the key prerequisite for safety, advocating that engineers and a pilot be included at the highest level on the decision making board of manufacturers.


Have flown nothing but Cessna but but I am with him!

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