ET crash ADD NBO

[Boac]

Boeing offered no comment when contacted by Boeing.

Says it all, really....

Seriously, I would not want a 'We're gonna die, Frank' light in my cockpit. Much rather have a reliable correctly made system.

[Boac]

Doubtless M O'Ls team are putting together a hard bargain to snap up the unwanted 'frames at knockdown prices

Indeed, I suspect there will be some 'bargains' to be had, and probably some way of charging pax to do something about it.

[G-CPTN]

Have we any way of knowing how many 737 Max aircraft are currently in build and not yet delivered? - including parts in manufacture.

I guess that, as suggested, the 'fixed' aircraft will be discounted and taken by LoCos.

This will cost Boeing $$$$ - what about loss of use during current suspension?

[G-CPTN]

Will the CAA now insist on full certification? along with the associated retraining for pilots?

[ian16th]

Do the airlines have any 'Consumer Protection' rights?

Can they sue Boeing for selling a/c that do not operate as advertised?

[ian16th]

Hot off the press podcast.

[Boac]

Even they have got it wrong! MCAS is not there to 'lower the nose to prevent a stall'. It is there to correct an incorrect stick force/alpha relationship at high AoA.

[boing]

This is pure semantics. How can you have a "disagree" light in a single-channel system?

Having a light that indicates a parameter in the system is outside of acceptable limits is a "fail" light, it is not a "disagree" light.

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[llondel]

To me, the 'disagree' warning should have been standard from the start. Any time you've got multiple instruments feeding data into the system, the pilots should be made aware of the issue if they're not tracking each other. If nothing else it's an added clue when things start to go pear-shaped, at best they can take action to decide which of the instruments to believe (and change that choice if they realise they picked the wrong one).

[llondel]

This is pure semantics. How can you have a "disagree" light in a single-channel system?

Having a light that indicates a parameter in the system is outside of acceptable limits is a "fail" light, it is not a "disagree" light.

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My understanding is that there are two instruments, but it was only using the input from one at any given time, not comparing the two. Of course, with two, how do you know which one to believe?

[Undried Plum]

It is 'single-channel' in that only one is used at a time.

There are two, which operate one at a time, alternately with each power-up cycle.

The $65k optional extra mod shows a warning if the two disagree and also shows the alpha in degrees for each of the units and shows which one is in use.

That's my understanding, anyway. (I've never flown a Boeing, but I've read a wee bit about this Max oddity since the Lion Air thing happened.)

[Undried Plum]

how do you know which one to believe?

If you've got a massive bust, such as 20°, then it should very fairly obvious which one wildly differs from what you'd expect from the A+P=Perf equation.

[Boac]

I don't think the 'Disagree' light is going to cost £65k? I was under the impression that was the cost of the 'GT' mod which had displays on EFIS and all sorts of other gismos. A simple light which compares AoA1 v AoA2 should be a lot cheaper (basically FREE!). You do not need to know which is right either - since you never use AoA to fly a 737"! You just need to know things are not sweet and be prepare for a possible MCAS malfunction.

At even greater cost would be to feed both AoAs into a comparator before feeding to MCAS.

[boing]

In 27 years of flying airliners with AOA vanes I do not remember a failure.

Why two failures in close time proximity on two brand new aircraft of the same type? Are we sure it is the actual sensor causing the problem? Is Boeing getting its vanes from the lowest cost supplier?

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[Undried Plum]

Are they, perhaps, positioned slightly differently from the NG?

Are they getting whacked by jetways or some such vehicle?

[Boac]

Are they getting whacked by jetways or some such vehicle?

- that thought has been bothering me for a while, since I THINK it is the P1 vane that has defaulted each time.

[boing]

Now you have bought up the idea of damage one possibility I can think of is that the fuelers would sometimes pass the final fuel sheet up to a cockpit window on a sort of long cleft stick which could hit the vanes. Chances of it happening twice remote.

It could be that a batch of bad probes was delivered and they were used in consecutive aircraft which would mean it was a good idea to ground the aircraft.

Talked to a friend who is an ex-Boeing employee who worked in the Flight Test Engineering Department. He confirmed what we all know by now. Re-certification of an aircraft is very expensive and time consuming. He firmly believes that the company employee "FAA designated inspector" program has got out of hand and his big question is how Boeing and the FAA managed to "lose" the information on the change to the stabilizer trim range.


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[barkingmad]

Putting on my corporate "can we do it cheaper" hat, IF it is found to be erroneous inputs from the only AOA sensor in the village, howzabout one each separately fed BIG white needle analogue AoA indicator high up in either the coaming or instrument panel easily seen & understood by PF & PNF and any extra qualified pilot who happens to be watching?

I understood during my 10 years on the 'NG' that the single probe and wiring were on every 'frame and it was only a chargeable extra to the customer airlines which rejected an indicator on the flight deck.

The industry has had far too many LOC accidents where the crew misunderstood what was happening to the Bernoullis and following on from AF447 and others there were calls for such a display to be made available, along with suitable training, but those who think they know better elected not to specify this option on cost grounds.

I do not suggest for a moment that poling an airliner around the SIDS, airways and STARs using the AoA to extract maximum performance out of the craft to keep the beancounters happy should become SOP. BUT, when the chips are down it appears to be a cheap fix and standard fit compared with the squillions of dollars which this latest blooper will cost Mr B and may have cost Mr A in the past.

Especially when a system such as MCAS was installed without any redundancy capability, then the addition of an extra AoA probe and indicator should have been included on standard ex-factory 'frames to avoid single sensor defects contributing to hull losses and the appalling and tragic human costs.

Again I wonder where was the grumpy old high-hours pilot(s) at the meetings where such a system was discussed and approved??

But now they're looking at a SOFTWARE FIX?! Anyone who's used a computer in the last few decades must be shaking their heads in disbelief and wondering how comfortable they'd be at letting themselves or family to climb aboard such an assembly.

And of course the factory geeks will recoil in horror at the thought of a ghastly analogue indicator, so even if they were persuaded to fit a duplex sensor and indication mod, doubtless they would try and squeeze such indication into the already crowded primary EFIS instead of a standalone indicator which screams information.

Somewhat similar to BA specifying BIG FAT WHITE NEEDLE non-EFIS engine instruments, after the Kegworth disaster, for its fleet of CFM powered 737s. And therein hides another 2 instances of failures by the relevant AAs to stand up to industry cutting corners.

[Boac]

Not sure, bm, whether the 'average' pilot would even notice! Let's face it, la creme du Air France couldn't even understand a basic attitude indicator in AF447, so confusing them with another dial....?

[Fox3WheresMyBanana]

This AoA gauge exists, as you describe - it is also an "optional extra".

Software fix is the OK language. If they say "hardware fix", the whole fake certification story unravels, and they are still trying desperately to avoid admitting this for legal reasons. It is possible that Boeing could go bankrupt over this.