Vocal Voices

The company is suspending production of the 737 MAX, which is the type of plane that was involved in two fatal crashes.

It has got 400 of them in storage worth around $40tn, and a further 500 are grounded around the globe costing airlines $millions every day.

If the company does not get clearance to fly them very soon and / or airlines make a class action to recover costs it could finish Boeing as a business.

Once approved, a retro-fit of the system operating the horizontal stabilisers (rear wings) is going to cost a fortune and take ages - it is not simply a software parch. SELL!

Whistleblowers seem to be intimating that Boeing were cavalier not only in their development and production processes, but also in the airworthiness certification of the plane. Apparently the FAA delegated much of this work back to Boeing itself, equivalent of marking your own homework …..

SELL! is right. There's already a huge amount of litigation under way and its only going to increase.

Hype aside, my understanding is that the crashes were a combination of 3 things.

The software working on the basis of only one, malfunctioning sensor

It being far too difficult to override the software (one crash was avoided by a pilot hitching a lift who had just been on the training course)

Boeing (and by implication the FAA), allowing the third air speed sensor to be optional.

All Fly By Wire systems work on a voting system where two, or more, inputs out vote the bad data. In this case there were only two sensors and the software defaulted to the sensor showing the lowest airspeed. Regardless of the fact that the failure of these sensors almost always results in a reduced airspeed reading.

It is no surprise that the planes which crashed were operated by airlines that bought the cheapest models and then carried out the least maintenance and training.

The fix is also multi faceted.

The software has to be fully reviewed and updated. Planes have to be updated with a full array of sensors and every pilot has to be trained; before the planes can fly again.

Probably Sell but I doubt they will go under. The government and NASA can't afford them to.

To clear up a few things.

The cost of the aircraft is fixed by Boeing due to its variant type - fuselage size, engines, range, number of passengers etc: MAX 7: $99.7Mn to MAX 10: $134.9Mn. The 'cheapest' variant was the 737 MAX 7, but all 32 of them were built to the same tech specs. However. Lion Air and Ethiopian were operating the much more expensive MAX 8 at $121.8Mn.

Conversion training for the MAX variants was by two self-administered courses from 1 hour to 3 hours, but with no simulator time involved as it was not considered to be a 'new' aircraft from the older 737 series. ALL pilots had to do it.

All aircraft have to undergo 'least' maintenance, both preventative and operational: every one. These checks are done based on 1. flight hours and 2. time: 6/8/12 months. They start as service checks and become more detailed as time passes. All operators have to have in place a Continuous Airworthiness Maintenance Program (CAMP) in order to fly.

After the Indonesian crash the FAA ordered Boeing to rewrite its pilot training manuals to include ways to mitigate a malfunctioning stabiliser system MACS. So, (part of) the problem was known about before the Ethiopian crash, unfortunately the system was not malfunctioning it was working as designed, yet if a pilot suspected that it was causing problems and wanted to take manual control it was difficult to switch off.

The rewrite gave instructions on how to do this which were not in the originals.

There was a programme on TV the other week showing pilots in a simulator trying to override MACS and get the stabilisers in a neutral position, It was so long-winded and physically exerting that they concluded that the Ethiopian crash was inevitable.

All true WM, but there are some fine points.

The MAX 8 is more expensive because it is bigger and carries more passengers. But Base Price is BASE. As we both know the base model comes in multiple variants and the number of sensors, layout of the cabin, seat types, etc, are custom specific orders.

Planes which operate under the FAA and CAA rules have to live up to different standards. For instance if you have two sensors and one is not functioning, you have to get it fixed or the plane can't fly. But they'll let it fly with 2 for a limited period of time. Other areas in the world have different standards to that. So planes in the FAA/CAA areas tend to have 3 sensors. It makes sense as it keeps them in the air longer.

Lion Air had 10 of the planes, Ethiopian had 4. Yet hundreds had been sold around the world, mainly in the US and China. Yet the airlines with less planes saw the issue. This goes against the law of averages. Except when you factor in airworthiness standards and the specs of the model bought.

As for the training. The "recommended" training is the base. Most airlines have their own training programmes. Ask any air accident investigator and they will tell you that the number of accidents (without manufacturer issues), is almost 1:1 with the level of training and simulator time that the airline gives the pilots.

Granted Boeing screwed up big time with the software, the way it operated, the training requirements and the laborious method of disabling the MACS module. But, then again, we cannot ignore that fact that an off duty pilot, hitching a ride, was able to talk the flight crew through disabling MACS. It might be bloody difficult but it is not impossible.

Yes, you say it was operating as designed. It's useful to know where this design comes from and why. I follow up air crashes to see what the final report was, especially where the route is one I take. Take for instance the Air France flight that went down in the Atlantic. The plane flew into weather which exceeded the FBW capabilities and the plane handed back full control to the #1 pilot. Unfortunately the captain had gone to bed to sleep, the #2 pilot had decided to stay where he was and the #3 pilot was in the captains chair.

The #3 pilot tried to fly the plane over the storm and exceeded the ceiling of the plane. At which point, at over 500 knots it stalled. Over about 15 minutes, the plane continued to stall, the #2 pilot tried to override but the plane was designed to give the #1 pilot overall control and kept the nose up and the tail down.

The plane stalled into the sea at about 500mph tail first. All lives were lost.

So when you say "operating as designed", yes it was. One of the air speed sensors told the software that the plane was stalling. It ignored the sensor which was working and put the nose down. Exactly what you do in a stall. Except the plane was not stalling and the pilots hadn't had enough training or knowledge transfer to disable the MACS system and it was bloody difficult to do.

This situation is slightly different from what we are reading in the press. The FAA are in full CYA mode and will not allow the plane back into the air until all feelings of guilt are assuaged. Just like NASA did with the SpaceX crew dragon when it blew up. SpaceX knew, within a few weeks, exactly what was wrong. NASA went into spiral control mode and SpaceX just got on with building their Starship until NASA grew a spine again.

I guess this will go on until the FAA are assured that Boeing have learned their lesson, the FAA has control back and the politicians on the hill can't blame them for letting the MAX back in the air.

Until then.... Money is being lost. Bucketloads. But at least people are not dying. Which is a good thing.

Base means 'Base', just that. It is the level at which a type or variant gets it Certificate of Airworthiness. There is not a lower level to make things cheaper. Yes the customer has some choice over passenger cabin design and facilities - seats, overhead storage etc, but even these have to meet a 'Base' spec. You cannot just bung in any old seats, toilets, kitchens and lockers.

The 737 MAX MCAS systems, all of them, work on one of two AoA sensors, not as many as the customer wants, and that creates a single point of failure which goes against the grain of an aircraft having in-built system redundancy. There is a general 'disagree' light indicator in the cockpit and customers can have an upgraded display built into the cockpit controls, but it has no 'system' control as it is informative. MCAS can be switched off, but as mentioned earlier it is no easy task. One problem that was highlighted in the simulator is that unlike the 737 NG (older standard) the MCAS turns off the electric motors to the stabilisers. This made the manual adjustment almost physically impossible. Try holding a car door open in a strong wind gust then multiply up the area and wind speed by factors of ten or to see how hard it would be to move a stabiliser.

Aircraft maintenance is highly regulated and must meet international standards. Maintenance bases and their staff must be licensed for the tasks they carry out. The standards are set and policed by the International Civil Aviation Organisation (ICAO). The ICAO standards have to be implemented by local airworthiness board in order for them to be allowed to issue airworthiness certificates. There are no "Backstreet Bobs" under the arches doing it cash-in-hand. If you are flying in a plane it has an internationally recognised and in-date certificate.

Where things do differ, and as a former aircraft worker of 18 years I do agree, it is with turnaround crews. They are a mixed bag and some countries, and even airports, do not have the best reputations. However, their performance was not a factor in either of the Boeing crashes.

I did say the third sensor was optional. Which means it is not in the base build.

Also whilst the ICAO standards have to be adhered to, certain countries operate a higher standard for planes registered in their own airspace. As can be seen in the FAA Gen 1.7 differences from ICAO standard that runs to hundreds (if not 1,000 or more, hard to tell), lines.

I agree about relying on a single sensor though, it is insane. Especially as they all have GPS today on which they can call for corroborating data. Having said that I doubt the software will disagree when it is 2:1. Only when it is a 50:50 choice.

My point is that whilst Boeing are culpable of not taking enough care with passengers lives and that the FAA was complicit in that fact; the crashes happened in airlines with very low numbers of the planes and in countries with lower standards of training and less diligence to the standards.

Something, as a very high rate air traveller, is important to me.

There is no third AoA sensor option, but I was wrong about the 'disagree' light and the angle of attack indicator display. They are options, but Boeing has now decided that the disagree light will be standard on all models - I mistakenly thought it already as. However, both are only informative but do act as visible early warning signals allowing the pilots to (possibly) act sooner.

When it comes to servicing there is no such thing as a lower standard. The standards at which airworthiness certificates can be issued are set - and policed. It is true that some, such as the FAA and CAA, ask for more, but there is no way to undercut the base. However, it cannot be denied that human error sometimes occurs, but that can happen anywhere.

But human error is reduced by extensive simulator training.

I'm sure I read that there was a third air speed sensor and it was optional. However it appears there were two but the software only read one.

Which is absolutely stupid. Apparently they are going to use both sensors now. I assume this is where the disagree light comes from which warns the pilots that the system has detected a disparity in speed readings.

The thing is they know what the fault was. Steps have been taken to rectify it. Nobody will be unaware of the situation and it is highly unlikely that it will occur again, given the software changes.

Still I expect the FAA to drag this out for at least another 6 months to a year so that everything can be considered fully resolved.

I do still stand by my assertion that the planes with better support services did not crash.

Plenty of issues with AOA sensors. Plenty of opportunity for pressure of work or mistakes to cause a disaster.

Airworthiness standards are exactly that, standards. Remember when the engines fell off the plane leaving Schiphol and it turned out that they had been using forklifts to remove and fit the engines instead of the correct jacks? Causing too much stress on the retaining bolts.

Flying-by-wire (FBW) confuses a lot of people. Many think that a plane FBW is being flown by computers for the whole of a journey. It is not.

At its very basic level FBW replaced the old electro/mechanical or hydraulic control surface actuators with all their very heavy pulleys, cables or pipes, with electric motor operated actuators. It's an old system and the pilot still flew the plane.

Auto-pilot also gets things confused. For the most part it keeps a plane on a heading, at a controlled height and speed giving the pilots a bit of a rest during long flights - it is not flying the plane. Later versions included take-off and landing in certain circumstances and at suitably equipped airports. It has been around in a workable form since the 1920s.

Then came flight management systems (FMS) and the introduction of some level of computer control over the flight plan. And so things went on, all the way up to aircraft flight control systems (AFCS).

It is these modern systems, using triplex or quadruplex redundant computer systems, constantly being fed sensor information to control ailerons, flaps, stabilisers, throttles, altitude, air temp, pressure and a whole lot more in real time, that utilise the FBW system to 'fly' the aircraft.

It is possible that one day planes will fly without pilots, but you will no more get me up in one than you will get me in a 'driverless' car.

Sorry Suff, but I also cannot let your apparent dissing of fellow aircraft workers just because they come from poorer countries to go unchallenged. Some of those I have worked with, and trained, are the equal of us superior beings. Live with it.