737 Max

[stevehnz]

10 hours ago, Jure Miljevic said:

reading it must be quite a task, especially in emergency situation. Cheers

very much my thoughts too @Jure Miljevic but I'm not in the industry though I have done some flying (Pa-28s) & try to keep up with developments in a layman type fashion. The lack of analogue back up in these aircraft, including the A320 family as I understand it, leaves them vulnerable to stuff the fly by wire developers didn't think of, witness the AirNZ A320 crash off the south of France & the Air France A330 crash in the Atlantic. As I understand this, reliance on digital instruments with faulty/compromised sensors led to both of these. I'm prepared to be put right if I'm mistaken on this.

Steve.

[busnproplinerfan]

Could this be the sign of the future? Where we over engineer to much? See that in everything now, just more things to go wrong.

[Jure Miljevic]

Hello Steve

I am in a similar position regarding a professional involvement in aviation. Yes, ever increasing role of computer in aviation concerns me, too. However, where to draw a line? In an interview decades ago one retired DC-9 trained Adria airline pilot called MD-80 series aircraft, puzzling as it may sound today, flying computers. Still, she must have looked like an ungrateful spoiled brat to her older colleges, who had previously piloted DC-6 propliners. In turn, these guys, who had had navigator, flight engineer and all sort of fancy radio equipment at their disposal, must have been regarded in more or less the same manner by pre-war airline pilots. Going back to airliners in which pilots gauged engine power by its sound, determined planes' airspeed by a pitch of whistling wires, maintain correct flying attitude by a feel of an air stream on their faces and judging load factors with a seats of their pants is probably impractical. Cheers

Jure

 

P.S.: I do not know about later series, but early production A320s certainly have analog back-up instruments. But, as you said, they are not much of help in case of faulty sensors.

[PZL104]

Flying an airliner with only the standby instruments is surprisingly simple. It doesn't matter if the backup instruments are mechanical or not. The point is that they need to have their pitot and static source.

But if the standby pitot and/or static port are damaged as well, then you don't have any reliable airspeed and altitude readout.

But you are still not doomed. In this case you still have the flight with unreliable airspeed tables which provide all necessary pitch and power settings so that you can safely fly without any speed indication.

Don't forget that in the ET case they did basically everything wrong long before MCAS kicked in.

[colin]

Until we know the facts from this crash I think it's unfair to say the crew did everything wrong before the MCAS kicked in

[PZL104]

Well, there are already sufficient facts known to safely state that they unfortunately did everything wrong right after takeoff.

Until a few years ago I was an airline pilot myself and I'm always very reluctant to blame the crew, but their actions were unfortunately well below any acceptable standard.

 

Edited April 23, 2019 by PZL104

[stalal]

Its end of the line for Boeing 737. Its easy to criticize flight crew after crash but it has been found that the aircraft is difficult to operate. Too much compromise in 737 MAX to make old infrastructure in the aircraft design to support modern engines and avionics.

 

https://www.nytimes.com/2019/04/08/business/boeing-737-max-.html

Edited April 23, 2019 by stalal

[bzn20]

7 hours ago, stevehnz said:

Air France A330 crash in the Atlantic

That was Iced up Pitots amongst other things . The Pitot heaters weren't switched on. One pulling the side stick, the other pushing. No mechanical linkage  which goes to what you were talking about . The Captain coming back from his sleep break to a disaster unfolding in the cockpit . He thought he had taken control but the other Pilot  still had control. The sticks move independently from each other.

[VMA131Marine]

2 minutes ago, bzn20 said:

That was Iced up Pitots amongst other things . The Pitot heaters weren't switched on. One pulling the side stick, the other pushing. No mechanical linkage  which goes to what you were talking about . The Captain coming back from his sleep break to a disaster unfolding in the cockpit . He thought he had taken control but the other Pilot  still had control. The sticks move independently from each other.

There was something else that contributed to this accident. In normal law, an A330 can't be stalled no matter how much the pilot pulls back on the stick. But, when the airspeed became unreliable, the aircraft went into alternate law where aerodynamic stalls are possible. Even more confusing, the stall warning is inhibited if the airspeed drops too low so even when the airspeed became reliable again the stall warning would be intermittent even though the aircraft was fully stalled for a large part of the event.

With all that, the accident should never have happened. The crew had reliable AOA data and should have been able to fly the plane on pitch and power until the pitots cleared and the airspeed became reliable again.

[bzn20]

Yes , it wasn't just a couple of things but a collection of them . I remember watching the Crash investigation programme on TV . Looked like a nightmare and getting worse with every passing second . I was wondering at the time why one of them didn't once look at the other's instruments to see if they had the same readings or look at the standby set , Do they have them on these ?

Here is a summary of the Final Report

temporary inconsistency between the measured speeds, likely as a result of the obstruction of the pitot tubes by ice crystals, causing autopilot disconnection and reconfiguration to alternate law

the crew made inappropriate control inputs that destabilized the flight path;

the crew failed to follow appropriate procedure for loss of displayed airspeed information;

the crew were late in identifying and correcting the deviation from the flight path;

the crew lacked understanding of the approach to stall;

the crew failed to recognize the aircraft had stalled and consequently did not make inputs that would have made it possible to recover from the stall.

 

These events resulted from the following major factors in combination.

feedback mechanisms on the part of those involved made it impossible to identify and remedy the repeated non-application of the procedure for inconsistent airspeed, and to ensure that crews were trained in icing of the pitot probes and its consequences;

the crew lacked practical training in manually handling the aircraft both at high altitude and in the event of anomalies of speed indication;

the two co-pilots' task sharing was weakened both by incomprehension of the situation at the time of autopilot disconnection, and by poor management of the "startle effect", leaving them in an emotionally charged situation;

the cockpit lacked a clear display of the inconsistencies in airspeed readings identified by the flight computers;

the crew did not respond to the stall warning, whether due to a failure to identify the aural warning, to the transience of the stall warnings that could have been considered spurious, to the absence of any visual information that could confirm that the aircraft was approaching stall after losing the characteristic speeds, to confusing stall-related buffet for overspeed-related buffet, to the indications by the Flight Director that might have confirmed the crew's mistaken view of their actions, or to difficulty in identifying and understanding the implications of the switch to alternate law, which does not protect the angle of attack.

[PZL104]

32 minutes ago, bzn20 said:

1. The Pitot heaters weren't switched on.

2.One pulling the side stick, the other pushing. No mechanical linkage  which goes to what you were talking about . The Captain coming back from his sleep break to a disaster unfolding in the cockpit . He thought he had taken control but the other Pilot  still had control. The sticks move independently from each other.

1. That's definitely wrong since you can't turn them off in any Airbus. You can only switch them from AUTO (normal state) to ON. There's no OFF position.

 

2. In case both pilots are moving the sidestick at the same time you get a very loud DUAL INPUT voice warning. Furthermore there's only one button on the sidestick, which is the takeover button.

If you push it (which you automatically do when taking over the controls from the other pilot) you get another loud aural warning. PRIORITY LEFT/RIGHT, plus and green/red colored arrow right in front of your nose which points to the side which has actual control. 

Last but not least you can see the hand of the other pilot on his sidestick.

[bzn20]

2 minutes ago, PZL104 said:

Last but not least you can see the hand of the other pilot on his sidestick

In 2010 Airbus issued a Bulletin that they must be fitted with Pitot Heaters with warning lights that the heating has failed.. It wasn't off ,there wasn't one. then ?

Side stick confusion on the day

The flight controls are not mechanically linked between the two pilot seats, and Robert, the left-seat pilot who believed he had taken over control of the aircraft, was not aware that Bonin continued to hold the stick back, which overrode Robert's own control (until just before hitting the Sea)

I think some of what you said came from recommendations of the Final Report, other bits were missed by the Captain as regards side stick in use and the right seat overriding . Where was  the dual input warning ? Not there ,ignored/cancelled or fitted after ? I get the impression the crew missed or didn't know quite a lot of what they were dealing with .

A320 series jet's Pitots were replaced ,they were having problems with the ones fitted . A330/340s changed from Goodrich units to  updated Goodrich or Thales tubes

 

[Alan P]

On Boeing FBW types, the flight controls are physically moved by servos like traditional mechanical ones. There's no ambiguity. You can tell what the control input is by analogue feedback (just put your hands and feet on the controls!) Also, and crucially, the pilot can override the FBW envelope protection (although it will make you work for it in muscle power!)

 

MCAS is an Airbus-like alpha floor protection that wasn't configured for the Boeing control model (there is no analogue feedback or pilot control override, unlike the FBW controls.) It was a hasty add-on and the full implications of operation were not adequately described.

 

Loss of control is the leading cause of flight accidents and I concede it's not just automation that's to blame. However, I'd recommend waiting until the final report before passing judgement on the pilots.

 

I* wrote this article a while back which looks at some of the misperceptions of automation.

http://www.jobsinaviation.com/aviation/careers-advice/how-much-does-autopilot-govern-flying-aircraft/

 

*Pen name 😎

Edited May 1, 2019 by Alan P

[baldwin8]

On 4/23/2019 at 3:35 AM, stevehnz said:

 the AirNZ A320 crash off the south of France

 

This event was a maintenance practice cause. After 40+ years in the aviation maintenance, digital or analog makes no difference. I've seen cases of control cables for engine/flight controls not installed/adjusted correctly, etc etc..

[busnproplinerfan]

Maybe it's been said already. Can Boeing abandon the new engines and reengine them with something else? I guess basically go back to the regular -800. What about the -900 series, never see many of those around. One more question, is there a military version of the Max? If so were they grounded to?

[Alan P]

Best article on the whole sorry mess I've found so far. Well worth a thirty-minute read.

 

https://www.theverge.com/platform/amp/2019/5/2/18518176/boeing-737-max-crash-problems-human-error-mcas-faa

Edited May 2, 2019 by Alan P

[bzn20]

1 hour ago, Alan P said:

Well worth a thirty-minute read

That was well worth reading and quite a bit has already been said by a few on here . Going back to a  design started in 1964 and tweaking it beyond 1967  (First Flight April 1967, entered Lufthansa service early 1968) 737 type certification . Oh and don't tell them anything until  they need the QRH in hurry .

Thanks very much for that link .

[colin]

A very good read shedding light on a tragedy that should never really have happened

[stevehnz]

It makes me wonder why this took so long to come to light & were there previous incidents with better outcomes?

Steve.

[busnproplinerfan]

If Boeing is found at fault, will they ever fess up to the problem? I kinda doubt it. To bad because they do make a pretty good plane. This will be one for the aircraft books a few years from now.

[Alan P]

27 minutes ago, busnproplinerfan said:

If Boeing is found at fault, will they ever fess up to the problem? I kinda doubt it. To bad because they do make a pretty good plane. This will be one for the aircraft books a few years from now.

More likely it'll be one for the lawyers. It might take a huge settlement to keep it out of court, but that's one price I think the manufacturer will be willing to pay given the likely effect on their order sheet.

 

The real thing to watch will be whether the  US regulatory culture towards Airbus/EADS will change following the public washing of all this dirty laundry. I don't think we've really seen how far the current administration is willing to go in the name of protectionism, especially when the company concerned is a giant defence contractor whose CEO is on personal terms with the President.

 

Watch this space.

Edited May 2, 2019 by Alan P

[busnproplinerfan]

22 minutes ago, Alan P said:

More likely it'll be one for the lawyers. It might take a huge settlement to keep it out of court, but that's one price I think the manufacturer will be willing to pay given the likely effect on their order sheet.

 

The real thing to watch will be whether the  US regulatory culture towards Airbus/EADS will change following the public washing of all this dirty laundry. I don't think we've really seen how far the current administration is willing to go in the name of protectionism, especially when the company concerned is a giant defence contractor whose CEO is on personal terms with the President.

 

Watch this space.

You said what I was thinking but couldn't formulate it. Trump and the CEO are buddies. Companies don't compete for contracts, now it's who pads the political party the most. Same thing with the F-35 in Canada, but that's another song.

[Max Headroom]

Wasn’t there something similar with a rudder problem on the 737 a few years ago? What happened there?

 

Trevor

 

[VMA131Marine]

16 minutes ago, Max Headroom said:

Wasn’t there something similar with a rudder problem on the 737 a few years ago? What happened there?

 

Trevor

 

That was a completely different type of problem, and I believe it only affected the -300 and -400 series aircraft. 

 

The problem was mechanical in nature in that, under certain rare conditions, the hydraulic rudder actuation servo could reverse operation so that, for example, a command for right rudder would produce a left rudder movement. The inevitable result was a rudder hard-over that caused loss of control. It was suspected to be the cause in two fatal accidents and only detected after a third aircraft experienced the problem but was able to land safely.

 

One element of that problem that is similar to the MAX's MCAS is that the rudder servo was a potential single point of failure and did not have any functional redundancy or a fail-safe mode.

[Alan P]

8 hours ago, VMA131Marine said:

That was a completely different type of problem, and I believe it only affected the -300 and -400 series aircraft. 

 

The problem was mechanical in nature in that, under certain rare conditions, the hydraulic rudder actuation servo could reverse operation so that, for example, a command for right rudder would produce a left rudder movement. The inevitable result was a rudder hard-over that caused loss of control. It was suspected to be the cause in two fatal accidents and only detected after a third aircraft experienced the problem but was able to land safely.

 

One element of that problem that is similar to the MAX's MCAS is that the rudder servo was a potential single point of failure and did not have any functional redundancy or a fail-safe mode.

Very good summary. I was flying the 737 (300/700 series) at the time this issue was investigated and although there was no admission of liability by the manufacturer, all operators were required to train crews in dealing with this problem. One problem was that the simulators couldn't fully replicate the issue (we could simulate the rudder hard over but not the control reversal) and of course we knew the failure was coming when we trained it, which made the handling and successful outcome easier. The unsuspecting line crews who experienced it weren't so fortunate.

 

One outcome that became standard practice (even after the faulty hydraulic valve was replaced across the type) was the addition of 10kts to all flap placard speeds to aid control authority in the event of a control malfunction. But again, it never went to court, no liability was assigned, so there was no adverse effect on the aircraft's sales or reputation. I expect a similar resolution with the Max.

Edited May 3, 2019 by Alan P