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KLM's 737 Fleet Also Has Altimeter Problems  
User currently offlineJonjonnl From UK - England, joined Dec 2007, 135 posts, RR: 0
Posted (5 years 7 months 3 weeks 4 days 7 hours ago) and read 10072 times:

In this morning's news both in the Volkskrant and in luchtvaartnieuws.nl.

KLM has had in the past 6 months seventeen reported problems with the altimeters of their 737 fleet. In the document (that remains confidential) it is also stated that there may have been further incidents/problems that were not reported.

KLM stated that at this moment there are no problems and that they'll not confirm the news but that if there were any problems in the past, these have now been solved.

Links to the websites (Dutch only):

http://www.volkskrant.nl/binnenland/...t_problemen_hoogtemeter?source=rss

http://www.luchtvaartnieuws.nl/news/?ID=29881


joão in ncl
41 replies: All unread, showing first 25:
 
User currently onlineDALCE From Netherlands, joined Feb 2007, 1706 posts, RR: 7
Reply 1, posted (5 years 7 months 3 weeks 4 days 6 hours ago) and read 10046 times:

Then there should be more airlines if this really is a big issue?
Are there any other airlines reporting ( or trying to hide ) such problems?
If this is the case, Boeing could make some reservations in court I guess!



flown: F50,F70,CR1,CR2,CR9,E75,143,AR8,AR1,733,735,736,73G,738,753,744,77W,319,320,321,333,AB6.
User currently offlineSevernaya From Russia, joined Jan 2009, 1419 posts, RR: 1
Reply 2, posted (5 years 7 months 3 weeks 4 days 6 hours ago) and read 10025 times:



Quoting DALCE (Reply 1):
Then there should be more airlines if this really is a big issue?

Exactly my thought! It can't be the case that only TK and KL have this "problem" with the altimeter.



Всяк глядит, да не всяк видит.
User currently offlineTristarSteve From Sweden, joined Nov 2005, 4037 posts, RR: 33
Reply 3, posted (5 years 7 months 3 weeks 4 days 6 hours ago) and read 10003 times:

I am astounded that this is news!

This sounds quite normal to me. Rad Alts go wrong now and then, especially because the antenna are so sensitive to water.

I would expect any airline to be about the same.


User currently onlineN14AZ From Germany, joined Feb 2007, 2763 posts, RR: 25
Reply 4, posted (5 years 7 months 3 weeks 4 days 6 hours ago) and read 9959 times:

The question that comes to my mind is another one:

Surely, all over the world problems with the altimeters occur.
Why could this be the reason for the TK crash whereas in the other cases nothing serious happened?

And yes, I couldn't read all the other nine threads about the TK crash in AMS.


User currently offlinePHKLM From Northern Mariana Islands, joined Dec 2005, 1198 posts, RR: 2
Reply 5, posted (5 years 7 months 3 weeks 4 days 6 hours ago) and read 9907 times:



Quoting N14AZ (Reply 4):
And yes, I couldn't read all the other nine threads about the TK crash in AMS.

If you would, you'd see it is VERY normal for a altimeter to go haywire, deflection of radio signals differs from surface to surface. Indeed, this is no news and a usual media blow-up of things.


User currently offlineKappel From Suriname, joined Jul 2005, 3533 posts, RR: 17
Reply 6, posted (5 years 7 months 3 weeks 4 days 6 hours ago) and read 9885 times:



Quoting PHKLM (Reply 5):
you'd see it is VERY normal for a altimeter to go haywire

I don't know if this has been answered, but if it's so normal for the altimeter to go haywire, why is the autothrottle (on the 737) only linked to one altimeter?



L1011,733,734,73G,738,743,744,752,763,772,77W,DC855,DC863,DC930,DC950,MD11,MD88,306,319,320,321,343,346,ARJ85,CR7,E195
User currently offline76er From Netherlands, joined Mar 2007, 557 posts, RR: 1
Reply 7, posted (5 years 7 months 3 weeks 4 days 6 hours ago) and read 9852 times:



Quoting Kappel (Reply 6):
if it's so normal for the altimeter to go haywire, why is the autothrottle (on the 737) only linked to one altimeter?

Because the solution for an A/T not doing what it's supposed to do is so simple: just disconnect it and continue manually. It is considered such basic airmanship, there's not even a checklist for it.


User currently offlineLarshjort From Denmark, joined Dec 2007, 1487 posts, RR: 0
Reply 8, posted (5 years 7 months 3 weeks 4 days 5 hours ago) and read 9851 times:



Quoting TristarSteve (Reply 3):
I am astounded that this is news!

Agreed

Quoting Kappel (Reply 6):
I don't know if this has been answered, but if it's so normal for the altimeter to go haywire, why is the autothrottle (on the 737) only linked to one altimeter?

Because the autothrottle is not deemed a critical system, if autothrottle isn't working thepilots can adjust throttles themselves.

/Lars



139, 306, 319, 320, 321, 332, 34A, AN2, AT4, AT5, AT7, 733, 735, 73G, 738, 739, 146, AR1, BH2, CN1, CR2, DH1, DH3, DH4,
User currently offlineLarSPL From Netherlands, joined Apr 2002, 473 posts, RR: 0
Reply 9, posted (5 years 7 months 3 weeks 4 days 5 hours ago) and read 9773 times:

Let's cut this crap;

Boeing issued a bulletin a while a go to check these radio altimeters.

KLM checked their aircraft and replaced a few.

Some Desk jockey or mechanic found out they replaced a few and thought: hey! we can make some interesting news out of it.

parts on aircraft brake down all the time.



facebook.com/ddaclassicairlines
User currently onlinePW100 From Netherlands, joined Jan 2002, 2518 posts, RR: 12
Reply 10, posted (5 years 7 months 3 weeks 4 days 5 hours ago) and read 9750 times:



Quoting 76er (Reply 7):
Because the solution for an A/T not doing what it's supposed to do is so simple: just disconnect it and continue manually. It is considered such basic airmanship, there's not even a checklist for it.

Absolutely agreed.

A/T is definately not considered to be a flight critical system as there is only one available. If it would be considered flight critical in any way, certification bodies would have made sure that at least two or three A/T systems would be required.

When the A/T system fails to perform its expected task properly, the crew are upfront to disconnect and take control. The PF [Pilot Flying] is the first back-up, the PM [Pilot Monitoring / PNF] is the second back-up. Together they form dual redundancy.
BTW, the crew are not expected to monitor the functionality of the A/T system, just its expected output [=airspeed]. Indeed the very basics of airmanship.

Failure of the A/T system is such a basic non-event, that it does not compromise the airworthiness status of the aircraft in any meaningful way. The only negative thing that will happen is that aircraft will not be able to perform poor visability approaches and autolands, as the A/T must be serviceable to do that. That is a dispatch reliability problem, not airworthiness.

From airworthiness point of view it is totally irrelavant what causes failure of the A/T system; either it be a software logic problem, hardware malfunctioning, or radio altimeter going haywire. Off course monitoring airspeed [or maybe better: energy management] is very important. Which is why this is the very first thing you learn as a pilot, whether you're flying a glider, Cessna 150, B737, F-16 or A380 . . .

Regards,
PW100



Immigration officer: "What's the purpose of your visit to the USA?" Spotter: "Shooting airliners with my Canon!"
User currently offlineShankly From United Kingdom, joined Jan 2000, 1547 posts, RR: 1
Reply 11, posted (5 years 7 months 3 weeks 4 days 5 hours ago) and read 9720 times:



Quoting PW100 (Reply 10):
From airworthiness point of view it is totally irrelavant what causes failure of the A/T system; either it be a software logic problem, hardware malfunctioning, or radio altimeter going haywire. Off course monitoring airspeed [or maybe better: energy management] is very important. Which is why this is the very first thing you learn as a pilot, whether you're flying a glider, Cessna 150, B737, F-16 or A380 . . .

Agreed. Aviate, navigate, communicate



L1011 - P F M
User currently offlineJonjonnl From UK - England, joined Dec 2007, 135 posts, RR: 0
Reply 12, posted (5 years 7 months 3 weeks 4 days 5 hours ago) and read 9698 times:



Quoting PW100 (Reply 10):
The only negative thing that will happen is that aircraft will not be able to perform poor visability approaches and autolands, as the A/T must be serviceable to do that. That is a dispatch reliability problem, not airworthiness.

In the unlikely event that this should happen and under these circumstances you have just described, what consequences could this have?



joão in ncl
User currently offlineRheinwaldner From Switzerland, joined Jan 2008, 2245 posts, RR: 5
Reply 13, posted (5 years 7 months 3 weeks 4 days 5 hours ago) and read 9674 times:



Quoting PW100 (Reply 10):
If it would be considered flight critical in any way, certification bodies would have made sure that at least two or three A/T systems would be required.

I think you will see this change. Quite certainly it will be required by certification bodies in the future. Let's wait and see.


User currently offlineKappel From Suriname, joined Jul 2005, 3533 posts, RR: 17
Reply 14, posted (5 years 7 months 3 weeks 4 days 5 hours ago) and read 9674 times:



Quoting 76er (Reply 7):
Because the solution for an A/T not doing what it's supposed to do is so simple: just disconnect it and continue manually. It is considered such basic airmanship, there's not even a checklist for it.



Quoting Larshjort (Reply 8):



Quoting PW100 (Reply 10):

Thanks for the info guys

Quoting PW100 (Reply 10):
that aircraft will not be able to perform poor visability approaches and autolands,

And that was exactly what the TK flight was doing, right?



L1011,733,734,73G,738,743,744,752,763,772,77W,DC855,DC863,DC930,DC950,MD11,MD88,306,319,320,321,343,346,ARJ85,CR7,E195
User currently onlinePW100 From Netherlands, joined Jan 2002, 2518 posts, RR: 12
Reply 15, posted (5 years 7 months 3 weeks 4 days 4 hours ago) and read 9604 times:



Quoting Jonjonnl (Reply 12):
In the unlikely event that this should happen and under these circumstances you have just described, what consequences could this have?

Well, first of all it is not very unlikely.

If the radio altimeter or A/Y system is unserviceable prior to departure, and weather at destination airport is below minima, then obviously the flight would be delayed or cancelled. If weather is at or around minima, then additional fuel could be uploaded to allow extra holding time, or to include an additional diversion destination.

If the problem occurred while inflight, depending on fuel status, the crew could elect to enter a holding and wait for the weather to clear up to Cat.1, where autoland functionality is not required and a manual landing could be performed. Alternatively the flight could divert to the nearest suitable airport, or any alternate airport available. Also return to departure airport could be an option depending on how far the flight has proceeded to desitantion.

This all is part of dispatch considerations in airline flight planning departments prior to departure, and continuing in real time in-flight as flights progress and circumstances change.

Plenty of options available that should not jeapordize flight safety in any way.

Regards,
PW100



Immigration officer: "What's the purpose of your visit to the USA?" Spotter: "Shooting airliners with my Canon!"
User currently onlinePW100 From Netherlands, joined Jan 2002, 2518 posts, RR: 12
Reply 16, posted (5 years 7 months 3 weeks 4 days 4 hours ago) and read 9559 times:

Quoting Kappel (Reply 14):
And that was exactly what the TK flight was doing, right?

No. Wheather minima was well above what would be considered poor visability, at least from a point of view requiring autoland capability. Conditions were perfectly acceptable for maunal approach, therefore radio altimeter, or A/T serviceability was not a requirement for this landing.

Quoting Rheinwaldner (Reply 13):
I think you will see this change. Quite certainly it will be required by certification bodies in the future. Let's wait and see.

Not sure if I agree. Beyond monitoring aircraft energy state during one of the most critical phases of flight, there are a lot of other tasks to be carried by the crew that are not or partially controlled by automation. Do certification specifications also take those tasks sufficiently into consideration? If all of those tasks are covered to the third redundancy by automation, and all thinkable and unthinkable failures can be handled by automation, who needs a crew upfront . . . ?

Having said that I see where you´re coming from, and I think I agree that the certification authorities probably will reconsider how we allow single-channel automation to manipulate flight critical settings [such as throttle setting] in critical phases of flight - also considering TAM 320 where automation did not help a speedy cutting of power on a long landing.

Regards,
PW100

[Edited 2009-03-11 05:01:09]


Immigration officer: "What's the purpose of your visit to the USA?" Spotter: "Shooting airliners with my Canon!"
User currently offlineKappel From Suriname, joined Jul 2005, 3533 posts, RR: 17
Reply 17, posted (5 years 7 months 3 weeks 4 days 4 hours ago) and read 9432 times:



Quoting PW100 (Reply 16):
No. Wheather minima was well above what would be considered poor visability, at least from a point of view requiring autoland capability. Conditions were perfectly acceptable for maunal approach, therefore radio altimeter, or A/T serviceability was not a requirement for this landing.

I realize that a manual approach/landing was possible, but they, as far as I understand at least, were performing an autoland. That's what I meant.



L1011,733,734,73G,738,743,744,752,763,772,77W,DC855,DC863,DC930,DC950,MD11,MD88,306,319,320,321,343,346,ARJ85,CR7,E195
User currently onlinePW100 From Netherlands, joined Jan 2002, 2518 posts, RR: 12
Reply 18, posted (5 years 7 months 3 weeks 4 days 2 hours ago) and read 9269 times:



Quoting Kappel (Reply 17):
I realize that a manual approach/landing was possible, but they, as far as I understand at least, were performing an autoland. That's what I meant

OK, I see what you mean. No, they were not going to autoland. Well, let me put it this way: single autopilot autoland is not an approved procedure.

According the Dutch Safety Board [DSB], the Flight Data Recorder revealed that Autopilot B was activated, as the [single channel] Auto Throttle. Autopilot A was not engaged.

Autoland requires both autopilot channels to be engaged, as well as the autothrottle. This suggests that they were not in autoland procedure, but that they were merely using the autopliot as a tool to reduce workload during the initial stages of approach. At some altitude they would have been required to disengage the autopliot system, and finish the apporach manually.

Some airlines require their crew when they do not auroland, to disengage the autopliot [and autothrottle?] between 1000 and 2000 ft. The exact numbers differ from airline to airline, but the general idea is that you are allowed to use the autopilot to start the approach and intercept the ILS, but that the remainder of the apporach and landing itself must be performed manually, unless fully in autoland mode -so to speak. I do not know if the autopliot will disengage itself, or that crew action is required to do so.

It is my understanding that the B737-800 will do autoland using a single autopliot, but that this is not a published procedure in the aircraft Flight Manual; crew are not expected to use this [hidden] funtionality, and most crew weren't even aware of this before this tragic crash.

Regards,
PW100



Immigration officer: "What's the purpose of your visit to the USA?" Spotter: "Shooting airliners with my Canon!"
User currently offlineJRadier From Netherlands, joined Sep 2004, 4707 posts, RR: 50
Reply 19, posted (5 years 7 months 3 weeks 4 days 2 hours ago) and read 9251 times:



Quoting Kappel (Reply 17):
I realize that a manual approach/landing was possible, but they, as far as I understand at least, were performing an autoland. That's what I meant.

That doesn't really matter. As soon as your radalt goes u/s and takes the a/t with it, you either do a missed approach or continue while flying manually. Both would be legal.



For once you have tasted flight you will walk the earth with your eyes turned skywards, for there you have been and ther
User currently offlineOsiris30 From Barbados, joined Sep 2006, 3192 posts, RR: 25
Reply 20, posted (5 years 7 months 3 weeks 4 days 2 hours ago) and read 9251 times:



Quoting TristarSteve (Reply 3):
This sounds quite normal to me. Rad Alts go wrong now and then, especially because the antenna are so sensitive to water.

I would expect any airline to be about the same.

Thank you very much for pointing out early in this thread that this is *not* an uncommon thing. RAs are flaky at times, based on the very nature of what they do.

Quoting 76er (Reply 7):
Because the solution for an A/T not doing what it's supposed to do is so simple: just disconnect it and continue manually. It is considered such basic airmanship, there's not even a checklist for it.

Yep.

Quoting Rheinwaldner (Reply 13):
I think you will see this change. Quite certainly it will be required by certification bodies in the future. Let's wait and see.

Why? CAT III isn't required of any airframe (at least to my knowledge). It's a feature for airlines not the cert boards. A/T is a convenience feature not a safety feature. There are lots of aircraft flying around everyday without A/T.

Quoting Kappel (Reply 14):
And that was exactly what the TK flight was doing, right?

No. The TK flight wasn't planning an autoland. You can't do an autoland with inop RA, but you can still fly IFR/ILS.

Quoting Kappel (Reply 17):
I realize that a manual approach/landing was possible, but they, as far as I understand at least, were performing an autoland. That's what I meant.

See above. They didn't have the AP configured appropriately if they were planning an autoland from what I've read and I'm pretty sure they were planning a manual landing.



I don't care what you think of my opinion. It's my opinion, so have a nice day :)
User currently offlineRheinwaldner From Switzerland, joined Jan 2008, 2245 posts, RR: 5
Reply 21, posted (5 years 7 months 3 weeks 4 days 1 hour ago) and read 9054 times:



Quoting PW100 (Reply 16):
Not sure if I agree. Beyond monitoring aircraft energy state during one of the most critical phases of flight, there are a lot of other tasks to be carried by the crew that are not or partially controlled by automation.

Yes, but I think the automation which is implemented must fulfill stringent quality aspects. It must manage properly all reasonable and potentially dangerous failure modes.

Quoting Osiris30 (Reply 20):
Quoting Rheinwaldner (Reply 13):
I think you will see this change. Quite certainly it will be required by certification bodies in the future. Let's wait and see. Especially if that automation implements a potential dangerous feature like a retard mode. That retard mode must never go "on" at wrong occasions. And it is easy to validate the criterias before going retard.

Why? CAT III isn't required of any airframe (at least to my knowledge). It's a feature for airlines not the cert boards. A/T is a convenience feature not a safety feature. There are lots of aircraft flying around everyday without A/T.

But if that A/T has a retard mode there are several safety aspects. E.g. if the retard mode kicks in by error at say only 200ft above ground the timespan that would allow manual recovering may only be as small as 1..3 seconds. Such an error must be prevented at all circumstances. The automation must be designed to cope even with such extreme failure conditions (at 200ft with A/T on it would be a autolanding).

For RA's driving an A/T-retard-mode the built-in safety should be bullet proof.


User currently offline76er From Netherlands, joined Mar 2007, 557 posts, RR: 1
Reply 22, posted (5 years 7 months 3 weeks 4 days ago) and read 9014 times:



Quoting PW100 (Reply 18):
Autoland requires both autopilot channels to be engaged, as well as the autothrottle.

Guess that depends on the type. On my 744 I'm even allowed to conduct Cat IIIA autolands with the A/T inop. Otoh 2 independant RA sources are required.

Dunno what the 73NG book says about that.


User currently offlineAAR90 From United States of America, joined Jan 2000, 3477 posts, RR: 46
Reply 23, posted (5 years 7 months 3 weeks 3 days 23 hours ago) and read 8336 times:



Quoting PW100 (Reply 10):
The only negative thing that will happen is that aircraft will not be able to perform poor visability approaches and autolands, as the A/T must be serviceable to do that.

Except when using HUD. Then the A/P and A/T must be OFF for the final approach/landing.  Big grin

Quoting Rheinwaldner (Reply 21):
But if that A/T has a retard mode there are several safety aspects. E.g. if the retard mode kicks in by error at say only 200ft above ground the timespan that would allow manual recovering may only be as small as 1..3 seconds. Such an error must be prevented at all circumstances. The automation must be designed to cope even with such extreme failure conditions (at 200ft with A/T on it would be a autolanding).

For RA's driving an A/T-retard-mode the built-in safety should be bullet proof.

I think you are far too locked into the "automation" to see the obvious. FLYING an airplane is not about WATCHING the automation, but rather physically flying the plane. The 737 was originally designed in the 1960's... when pilots physically flew their aircraft. It still works well today. There is no need to "turn off" the A/T in the 738... just manually move the throttles and you'll get the thrust you want. If the A/T retards early it takes much less than one second to correct. And if you want a "smooth landing" in the 738, you either disconnect the A/T or override the retard command. The 737 is designed to be FLOWN by a pilot. This mishap was all about "pilots" not FLYING their airplane. Nothing more, nothing less.



*NO CARRIER* -- A Naval Aviator's worst nightmare!
User currently offlineAogdesk From United States of America, joined Jun 2004, 935 posts, RR: 3
Reply 24, posted (5 years 7 months 3 weeks 3 days 22 hours ago) and read 7839 times:

This is about as newsworthy as "Reports surface that aircraft tires and brakes are being replaced at an alarming rate.....how could that happen when they're in the air most of the time?? Undercover reporters smell a conspiracy"

Look beyond the sensational aspect of these "breaking news" reports. Sheesh.


25 Spitfire : How many times must we repeat and repeat and repeat ... always the same sentences ???? Do you think there is some brains at the top of their bodies ?
26 Spitfire : Let's say it simply : - when A/T is U/S (or if there is no) : WE are the A/T -when A/P is U/S : WE are the A/P So simple ......
27 Smeg : Or to put it another possibly simpler way. When the autopilot/autothrottle is turned off, there is a pilot flying and a pilot monitoring. (various te
28 EMA747 : I have to agree with this, although I don't have any real world flying experience so I am not speaking with authority. The way I see it [in relation
29 Smeg : Trouble is though, that the ferry doors opening are a catastrophic event that is not easily recoverable from. I prefer to compare it to driving on a
30 EMA747 : My analogy wasn't a very good one I admit. I understand what you are saying about the loss of speed etc. I was more refering to the throttles being s
31 Pylon101 : I am wondering. How this can be considered "normal", or OK??? Thousands of 737NG have been making autoland in CAT III airports all around the world. M
32 TristarSteve : I believe that, with a serviceable system, the A/P would not disconnect, until crew action. Most (90pc?) of airliner approaches are flown with a sing
33 Post contains links FatmirJusufi : " target=_blank>http://www.luchtvaartnieuws.nl/news/...29881 English source http://www.digitaljournal.com/article/268970 Fatmir
34 ComeAndGo : But that's not what happened. The RA did not fail, it showed an erroneous number. It did not display an error flag. The pilots assumed it irrelevant.
35 G-CIVP : TristarSteve, I'm always impressed with your technical knowledge and appreciate the balanced contributions on the forum. Tim.
36 AFGMEL : I can only speak as a private pilot when I say that in landing, particularly in final approach, your attention is on speed all the time. Particularly
37 Smeg : I agree with you that the RA did not fail. I was referring to the symptoms of that incorrect reading - Namely the decaying airspeed. They were appare
38 Birdbrainz : Well put. Someone needs to be flying the airplane. I never quite understood how people get the impression that the pilots are merely "along for the r
39 Spitfire : Yes there was a warning, altough not directly link to the A/T, BUT, when you are about to intercept an ILS at something like 2000 feet and you receiv
40 JRadier : Because we have pilots that monitor the vital signs and correct it... at least, up until now...
41 Planefxr : It will not due a full autoland, you will be missing Flare. A 737NG only has two autopilots meaning both are needed to do an autoland. This system is
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