B737 No Uptrim during Cat III
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If the AP was preparing for a GA, would it not trim Nose down to counter the pitch up when power was applied?? Next time you are in a sim, get to CAT I minima on 1 AP and press TOGA and don't touch the controls. The nose passes 20 degrees in about 3 seconds. Plus when the gear is selected up, that is a futher nose up trim change.
safetypee. Thanks for your post. Now that we have established you think we are lesser "pilots claiming to be professionals" its back to the original post.
What is your opinion???? If the AP disengages just after the decision to land, what would you do?? The thinking here is that runway contact is almost certain if a GA is executed. The result we are after is an A/C safely on the deck.
And do you continue if the Up Trim does not happen?? It could be a syptom of a latent problem about to manifest itself in the flare at <50ft in a RVR of 200m.......
A final note. There are now two threads which are designed to "set strait" the other posters on this thread. Why???? You don't even know who we really are, or what experience/positions we hold. I like to be able to discus the unusual, it often raises other questions. It is not as if we are going to try this in a real a/c. Discussion and debate is healthy, ie tech log on Pprune. So keep the posts sweet....
Mr L.
safetypee. Thanks for your post. Now that we have established you think we are lesser "pilots claiming to be professionals" its back to the original post.
What is your opinion???? If the AP disengages just after the decision to land, what would you do?? The thinking here is that runway contact is almost certain if a GA is executed. The result we are after is an A/C safely on the deck.
And do you continue if the Up Trim does not happen?? It could be a syptom of a latent problem about to manifest itself in the flare at <50ft in a RVR of 200m.......
A final note. There are now two threads which are designed to "set strait" the other posters on this thread. Why???? You don't even know who we really are, or what experience/positions we hold. I like to be able to discus the unusual, it often raises other questions. It is not as if we are going to try this in a real a/c. Discussion and debate is healthy, ie tech log on Pprune. So keep the posts sweet....
Mr L.
If the auto trimming does not occur, does the Red Autopilot P/RST light not come on steady (disagreement between autopilot command and actual position). Thus an immediate go-around!
I remember taking the autopilot out at 60 ft on a practice autoland due to aircraft trying to snap left due intereference. The pressure required to land the aircraft in a safe attitude was surprising. Not something I would care to do in real Cat 3 wx.
I remember taking the autopilot out at 60 ft on a practice autoland due to aircraft trying to snap left due intereference. The pressure required to land the aircraft in a safe attitude was surprising. Not something I would care to do in real Cat 3 wx.
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safetypee, thank you for your comments. My thoughts exactly.
Mr. Levitator, discussing the unusual is quite something else then boasting about one`s abilities to take the aircraft outside the limits, as mr. LEM is advocating:
He even goes as far as to say it is rewarding!
I seriously hope he will not go looking for more rewarding experiences.
Mr. Levitator, discussing the unusual is quite something else then boasting about one`s abilities to take the aircraft outside the limits, as mr. LEM is advocating:
Jokes apart, I'm half serious when I say that: the secret for landing without adequate visual cues (like in heavy rain with s*** wipers) is doing nothing. Just maintain constant parameters, disregarding your desire for visual certeinties, as following your senses will only screw up everything.
I seriously hope he will not go looking for more rewarding experiences.
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If you are that concerned, PM LEM.
What are your thoughts regarding the trim????
B737 No Uptrim during Cat III is the thread title, what are your opinions on it????
For a bunch of pilots, there is not a lot of RTFQ here?!?!?!?!
Use PM or another thead for b##ching. I am sure if you PM LEM he will explain his point more clearly to you, and as his quote says, LEM was actually suggesting that making unnecessary control input are exactly what takes the a/c out of limmits!! Its kind of like flying a raw data ILS, the closer to decision, the smaller and more gentle the loc and g/s corrections have to be.
So a futher question. Why nose up trim?? If it were for a G/A, would it not be nose down, for the pitch power couple and the gear retraction??
Mr L
What are your thoughts regarding the trim????
B737 No Uptrim during Cat III is the thread title, what are your opinions on it????
For a bunch of pilots, there is not a lot of RTFQ here?!?!?!?!
Use PM or another thead for b##ching. I am sure if you PM LEM he will explain his point more clearly to you, and as his quote says, LEM was actually suggesting that making unnecessary control input are exactly what takes the a/c out of limmits!! Its kind of like flying a raw data ILS, the closer to decision, the smaller and more gentle the loc and g/s corrections have to be.
So a futher question. Why nose up trim?? If it were for a G/A, would it not be nose down, for the pitch power couple and the gear retraction??
Mr L
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Mr. L - Yes that of course makes more sense. Have scanned through the manuals and can't really find any good explanation to this phenomenon 
Suspect that the engineers didn't really realize what a curious, kneed-to-know-every-little-detail, kind of people we are 
On the other hand, how could one make the right decision if put in LEM's situation, without knowing its function and more importantly what to expect when it's not functioning? Both AP's still engaged, FLARE armed and everything seems fine. One could always see this as a non-normal operation of the AP system and do a G/A. Or, one could say that if this was a G/A situation shouldn’t the logic of the AP disconnect or give a warning?
When it comes to the steady red AP light below 800 feet RA and during app, it will come on if the Stab is out of trim. And in this case it was more in trim than had the normal 400 feet RA nose-up trim taken place.
Found one little note on the subject though that refer to the automatic G/A.
"The pitch mode cannot be changed from TOGA until sufficient nose-down trim has been input to allow single channel AP operation. This nose-down trim is automatically added by the AP to reset the trim input made by the AP at 400 feet RA and at 50 feet RA during the approach."
The AP is actually trimming the airplane out of the single channel operational range, which makes even less sense as to my previous post about preparing for G/A. On the other hand, flying around with a nose heavy airplane close to the ground seems to be risky business should the AP suddenly disconnect.
So the question remains why the AP trim the airplane in this way so close to the ground. Doesn't seem to be any obvious logic to it. I mean doesn’t this trim go against the fail-passive definition? During fail-passive operations should the autopilot disconnect the airplane should be in trim which it clearly isn't below 400 feet RA?
The fact is that anything more nose heavy than in trim at this particular stage would in my opinion be an accident waiting to happen. So maybe that’s the answer? We heard that on the 757 there is a distinction between LAND2 and LAND3 (fail-passive and fail-operational). Maybe this is a safety precaution when getting close to the ground? Scenario; AP disconnects just before minima and you have insufficient visual cues. Time for a GA, right!? Well in this case the nose or the control column pressure will tell you exactly where to go: UP not down. The natural response will be to TOGA and to get that GA thrust in there… and then you got some trimming to do but at least then there will be no doubt about where you’re going... or supposed to be going.
During a dual channel app you are expected to let the AP do the landing, if a non-normal scenario presents it self the airplane will in a pretty obvious way suggest what it thinks you should do. During a single channel app this is not the case since you are expected to disconnect at the appropriate time.
Suspect that the engineers didn't really realize what a curious, kneed-to-know-every-little-detail, kind of people we are On the other hand, how could one make the right decision if put in LEM's situation, without knowing its function and more importantly what to expect when it's not functioning? Both AP's still engaged, FLARE armed and everything seems fine. One could always see this as a non-normal operation of the AP system and do a G/A. Or, one could say that if this was a G/A situation shouldn’t the logic of the AP disconnect or give a warning?
When it comes to the steady red AP light below 800 feet RA and during app, it will come on if the Stab is out of trim. And in this case it was more in trim than had the normal 400 feet RA nose-up trim taken place.
Found one little note on the subject though that refer to the automatic G/A.
"The pitch mode cannot be changed from TOGA until sufficient nose-down trim has been input to allow single channel AP operation. This nose-down trim is automatically added by the AP to reset the trim input made by the AP at 400 feet RA and at 50 feet RA during the approach."
The AP is actually trimming the airplane out of the single channel operational range, which makes even less sense as to my previous post about preparing for G/A. On the other hand, flying around with a nose heavy airplane close to the ground seems to be risky business should the AP suddenly disconnect.
So the question remains why the AP trim the airplane in this way so close to the ground. Doesn't seem to be any obvious logic to it. I mean doesn’t this trim go against the fail-passive definition? During fail-passive operations should the autopilot disconnect the airplane should be in trim which it clearly isn't below 400 feet RA?
The fact is that anything more nose heavy than in trim at this particular stage would in my opinion be an accident waiting to happen. So maybe that’s the answer? We heard that on the 757 there is a distinction between LAND2 and LAND3 (fail-passive and fail-operational). Maybe this is a safety precaution when getting close to the ground? Scenario; AP disconnects just before minima and you have insufficient visual cues. Time for a GA, right!? Well in this case the nose or the control column pressure will tell you exactly where to go: UP not down. The natural response will be to TOGA and to get that GA thrust in there… and then you got some trimming to do but at least then there will be no doubt about where you’re going... or supposed to be going.
During a dual channel app you are expected to let the AP do the landing, if a non-normal scenario presents it self the airplane will in a pretty obvious way suggest what it thinks you should do. During a single channel app this is not the case since you are expected to disconnect at the appropriate time.
Last edited by CrossBars; 16th Jan 2005 at 16:05.
MrL RTFQ??? Why nose up trim? Please read some of the possible reasons posted previously.
CrossBars your comment “the airplane should be in trim which it clearly isn't below 400 feet RA”, is an often quoted misunderstanding; see:
JAR–OPS 1.435 Terminology.
“Fail-Passive flight control system. A flight control system is fail-passive if, in the event of a failure, there is no significant out-of-trim condition or deviation of flight path or attitude but the landing is not completed automatically. For a fail-passive automatic flight control system the pilot assumes control of the aeroplane after a failure.”
Also see: JAR-AWO 109 Out-of-trim forces at disengagement
“It must be possible to disengage the automatic landing system at any time without the pilot being faced with out-of-trim forces that might lead to an unacceptable flight path disturbance.”
Therefore, it may be assumed that Boeing has demonstrated that the out of trim forces in the 737 are acceptable.
Re MrL your comment “What is your opinion???? If the AP disengages just after the decision to land, what would you do?? The thinking here is that runway contact is almost certain if a GA is executed. The result we are after is an A/C safely on the deck.”
There is another widely held misconception relating to completing a manual landing after an autopilot failure, see:
“IEM to Appendix 1 to JAR-OPS 1.430, paragraph (e)(5)
Crew actions in case of autopilot failure at or below decision height in fail-passive Category III operations.
For operations to actual RVR values less than 300m, a go-around is assumed in the event of an autopilot failure at or below DH. This means that a go-around is the normal action. However the wording recognises that there may be circumstances where the safest action is to continue the landing. Such circumstances include the height at which the failure occurs, the actual visual references, and other malfunctions. This would typically apply to the late stages of the flare. In conclusion it is not forbidden to continue the approach and complete the landing when the commander or the pilot to whom the conduct of the flight has been delegated, determines that this is the safest course of action. Operational instructions should reflect the information given in this IEM and the operators policy.”
Thus, I would interpret the above as a GA should always be flown, unless unsafe to do so. Any alternative interpretation, without obvious problems e.g. engine failure, generator trip, etc, would require an understanding of why a continued manual landing is safer than a GA. I would further suggest that crews do not have the expertise to judge why a manual landing would be safer in limiting visibility conditions. N.B touching the runway during a GA is not inherently unsafe, whereas landing on grass is.
Could someone give an operators interpretation of this (ops policy) as suggested by the IEM?
CrossBars your comment “the airplane should be in trim which it clearly isn't below 400 feet RA”, is an often quoted misunderstanding; see:
JAR–OPS 1.435 Terminology.
“Fail-Passive flight control system. A flight control system is fail-passive if, in the event of a failure, there is no significant out-of-trim condition or deviation of flight path or attitude but the landing is not completed automatically. For a fail-passive automatic flight control system the pilot assumes control of the aeroplane after a failure.”
Also see: JAR-AWO 109 Out-of-trim forces at disengagement
“It must be possible to disengage the automatic landing system at any time without the pilot being faced with out-of-trim forces that might lead to an unacceptable flight path disturbance.”
Therefore, it may be assumed that Boeing has demonstrated that the out of trim forces in the 737 are acceptable.
Re MrL your comment “What is your opinion???? If the AP disengages just after the decision to land, what would you do?? The thinking here is that runway contact is almost certain if a GA is executed. The result we are after is an A/C safely on the deck.”
There is another widely held misconception relating to completing a manual landing after an autopilot failure, see:
“IEM to Appendix 1 to JAR-OPS 1.430, paragraph (e)(5)
Crew actions in case of autopilot failure at or below decision height in fail-passive Category III operations.
For operations to actual RVR values less than 300m, a go-around is assumed in the event of an autopilot failure at or below DH. This means that a go-around is the normal action. However the wording recognises that there may be circumstances where the safest action is to continue the landing. Such circumstances include the height at which the failure occurs, the actual visual references, and other malfunctions. This would typically apply to the late stages of the flare. In conclusion it is not forbidden to continue the approach and complete the landing when the commander or the pilot to whom the conduct of the flight has been delegated, determines that this is the safest course of action. Operational instructions should reflect the information given in this IEM and the operators policy.”
Thus, I would interpret the above as a GA should always be flown, unless unsafe to do so. Any alternative interpretation, without obvious problems e.g. engine failure, generator trip, etc, would require an understanding of why a continued manual landing is safer than a GA. I would further suggest that crews do not have the expertise to judge why a manual landing would be safer in limiting visibility conditions. N.B touching the runway during a GA is not inherently unsafe, whereas landing on grass is.
Could someone give an operators interpretation of this (ops policy) as suggested by the IEM?
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LEM,
You say: But somebody is of a different opinion...
Looks like trouble for you.
Two questions arise. I don't know the 737 - as I'm just an ATR driver, so:
First: What does the AFM say about any alarms on a CAT III approach and the subsequent procedure to apply?
(Does it maybe say something like - GO AROUND?)
Second: What does your companies operation manual or procedure manual say about "ANY" alarm on an armed CAT III approach?
Ours says: GO AROUND! Simply because you cannot tell the system implication within - lets say (300 ft) = 20 sec? !!!
error_401
You say: But somebody is of a different opinion...
Looks like trouble for you.
Two questions arise. I don't know the 737 - as I'm just an ATR driver, so:
First: What does the AFM say about any alarms on a CAT III approach and the subsequent procedure to apply?
(Does it maybe say something like - GO AROUND?)
Second: What does your companies operation manual or procedure manual say about "ANY" alarm on an armed CAT III approach?
Ours says: GO AROUND! Simply because you cannot tell the system implication within - lets say (300 ft) = 20 sec? !!!
error_401
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error 401,
The issue is that there was no OFFICIAL alarm. There was no up trim at 400ft, which is no OFFICIAL check item either. LEM wants to know why there is no OFFICIAL check (call) in his company OM, neither in the B737 FCOM.
Although LEM was not very fortunate in his sentence build up. I think he deserves a bit more credit from some of you. He just wants to share an experience with us.
The issue is that there was no OFFICIAL alarm. There was no up trim at 400ft, which is no OFFICIAL check item either. LEM wants to know why there is no OFFICIAL check (call) in his company OM, neither in the B737 FCOM.
Although LEM was not very fortunate in his sentence build up. I think he deserves a bit more credit from some of you. He just wants to share an experience with us.
Last edited by Alaskan Timber; 17th Jan 2005 at 10:23.
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LEM, Alaskan,
Sorry for the misinterpretation.
Just a thought:
Even if there is no official alarm, obviously the system has a means of telling you that something screwed up. If it where a really minor thing than it may never show on the flight deck but would be limited to a read out for maintenance somewhere hidden in the gizmos behind your backs. So someone thought of it being at least so important to notify the pilots.
If unsure of a systems behaviour and at 400 feet (which I'd consider rather a safe altitude) would a go-around not be the safest way to cope with this "non-alarm" situation.
Not being 100 % sure about a systems behaviour when one parameter is missing i'd rather choose that option.
Maybe a continuation could be considered when absolutely sure that it won't affect the landing and you may even have played with that failure in the sim once or twice.
As for the OM or AFM - It's not the bible - so sometimes they do not think about every failure. The wording in LEM's OM might be interesting. Does it say something about "any" failure on a CAT III approach should lead to a go-around ... or is it fully specific with details on the various occurrences?
Sorry for the misinterpretation.
Just a thought:
Even if there is no official alarm, obviously the system has a means of telling you that something screwed up. If it where a really minor thing than it may never show on the flight deck but would be limited to a read out for maintenance somewhere hidden in the gizmos behind your backs. So someone thought of it being at least so important to notify the pilots.
If unsure of a systems behaviour and at 400 feet (which I'd consider rather a safe altitude) would a go-around not be the safest way to cope with this "non-alarm" situation.
Not being 100 % sure about a systems behaviour when one parameter is missing i'd rather choose that option.
Maybe a continuation could be considered when absolutely sure that it won't affect the landing and you may even have played with that failure in the sim once or twice.
As for the OM or AFM - It's not the bible - so sometimes they do not think about every failure. The wording in LEM's OM might be interesting. Does it say something about "any" failure on a CAT III approach should lead to a go-around ... or is it fully specific with details on the various occurrences?
Last edited by error_401; 17th Jan 2005 at 09:40.
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Alaskan - I do not know enough about the detail of the 737 system, but IF this failure were to produce a 'Stab out of trim' warning, the QRH calls for a go-round. IF it does not, then LEM's question needs to be addressed. Can anyone say if it would produce the warning?
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Hey error 401,
The credit thing was not meant for you.
I agree a lot of failures during a CAT III require a go-around and if unsure about something 99.9% I would make a go-around (the .1% is a double flame out).
My books are 200 NM seperated from me, so I cannot check it. The questions stays : Is the 400ft trim a requirement or not ? Does the aircraft always trim at 400ft whatever the IN TRIM or OUT OF TRIM (no STAB OUT OF TRIM light) situation is ? Or can it anticipate on this ?
What I know is that the 400ft uptrim is a preparation for the flare. If you notice that on the FMA the FLARE doesn't engage (green) then in a normal situation you are allowed to land manually. After A/P disconnect the aircraft is already in the postion to land (due to the trim at 400ft). It is even mentioned not to pull the stick anymore as you might start ballooning.
A.T.
Hey BOAC,
Our posts crossed each other. I understood from LEM's post that he didn't get a STAB OUT OF TRIM warning. Otherwise it is 100% a go-around.
The credit thing was not meant for you.
I agree a lot of failures during a CAT III require a go-around and if unsure about something 99.9% I would make a go-around (the .1% is a double flame out).
My books are 200 NM seperated from me, so I cannot check it. The questions stays : Is the 400ft trim a requirement or not ? Does the aircraft always trim at 400ft whatever the IN TRIM or OUT OF TRIM (no STAB OUT OF TRIM light) situation is ? Or can it anticipate on this ?
What I know is that the 400ft uptrim is a preparation for the flare. If you notice that on the FMA the FLARE doesn't engage (green) then in a normal situation you are allowed to land manually. After A/P disconnect the aircraft is already in the postion to land (due to the trim at 400ft). It is even mentioned not to pull the stick anymore as you might start ballooning.
A.T.
Hey BOAC,
Our posts crossed each other. I understood from LEM's post that he didn't get a STAB OUT OF TRIM warning. Otherwise it is 100% a go-around.
Last edited by Alaskan Timber; 17th Jan 2005 at 10:23.
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Alaskan,
Thanks for clarification on the credability issue.
Can you come back on the post once you are again united with your books?
I'd really like to know what company and manufacturer say about "any" failure or malfunction (or indication thereof) on an established CAT III.
TO ALL:
Any chance that someone knows someone at Boeing to get some insight on the tech side from the source?
Thanks for clarification on the credability issue.
Can you come back on the post once you are again united with your books?
I'd really like to know what company and manufacturer say about "any" failure or malfunction (or indication thereof) on an established CAT III.
TO ALL:
Any chance that someone knows someone at Boeing to get some insight on the tech side from the source?
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I understood from LEM's post that he didn't get a STAB OUT OF TRIM warning. Otherwise it is 100% a go-around.
I have always 'verbalised' the trim, even on a Cat I approach, as I consider it to be part of airmanship, but there is NO QRH action if it does not happen. I believe I was once told that the landing would be firmer but not unacceptable, but I have no documentation for that.
Someone said earlier that the 737 classic would autoland with single a/p? I really doubt that as there would be no flare function armed. Can anyone substantiate that?
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I can confirm the 737CL sim behavior on single AP. In fact, during a sim session with a 25,000h something instructor which had flown everything from the -200 to the various NG:s, specifically showed us this feature as a nice to know in case everything else goes out the window. We actually did it SE if I remember correctly.
The reason why the FLARE mode wouldn't be armed seems quite obvious since this is not a certified procedure. Just because the graphic isn't there on the screen doesn't mean the AP isn't prepared for it.
On the question on trim req for flare or not, I think that the behavior of the AP system on the 757 gives a good clue. LAND2 - trim. LAND3 - no trim. This seems to be a question about the fact that this is a fail-passive procedure.
I'll try to get hold of a former 737 technical pilot I know, who by my knowledge never been presented with a question about the 737 he's been unable to answer. 
The reason why the FLARE mode wouldn't be armed seems quite obvious since this is not a certified procedure. Just because the graphic isn't there on the screen doesn't mean the AP isn't prepared for it.
On the question on trim req for flare or not, I think that the behavior of the AP system on the 757 gives a good clue. LAND2 - trim. LAND3 - no trim. This seems to be a question about the fact that this is a fail-passive procedure.
Any chance that someone knows someone at Boeing to get some insight on the tech side from the source?
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Yes, as Alaskan Timber rightly says, my sentence build up is often unfortunate, my English being quite poor.
But... who cares!!
I'm a pilot, not a politician, nor a demagogue, as somebody on this forum.
When I mean bread I mean bread, when I mean wine I mean wine.
So, enough blah blah and back on stage!
XXXX
I'll start by quoting my LOW VISIBILITY OPERATIONS MANUAL:
"If, during a CAT III approach, a system failure occurs which requires intervention by the pilot, a go around will be performed, unless the aircraft is below DH and the Captain has adequate visual reference to complete a manual landing."
Also: "If a system malfunction or engine failure occurs below DH, the Captain may, provided adequate visual references exist, continue the approach and land manually."
(Italic is mine).
Some posters have expressed their concernment about manually landing in poor visibility, accusing me of machismo, disconcerting attitude, pushing the airplane beyond its limitations and rubbish like that.
I thought that legally meant safely, in aviation.
Have you ever realized we are allowed lo legally land with a 15mtrs visual segment, although displaced due to the slant visual range?
Yes, FIFTEEN METRES!
Disconcerting, isn't it?
How come 15 mtrs?
My book says: if after passing the OM or equivalent position the RVR decreases to below minimums, the pilot is allowed to continue down to the radio minima, and land if he is satisfied with the visual cues.
Now, once again, adequate visual cues means THREE longitudinal lights, i.e. THREE runway centreline lights, which can be spaced as close as seven and a half metres!
That gives a segment of 15 metres!
And, just to add to the fun, all this is perfectly valid in CAT II, with the addition of one lateral element, being one TDZ barrette.
Correct me if I'm wrong with all this math, but CAT II means manual landing !
Now, I understand some decades ago the idea of an airplane landing by itself was unbelievable to the general public, so I understand how people involved with the certification process have tended to cover their *** as much as they could.
So, as a last resort, if everything goes to worms and our pilots are sleeping, let's give us a last chance adding this uptrim which will prevent making a big hole into the runway.
Fine.
So now I've got at least two questions: why isn't there a warning if uptrim doesn't occur?
Why don't we have a callout for that? And why in the long and detailed list of all the required working components - and downgradable ones - there is no mention at all about uptrim?
In my manuals I cant't find anything about "... verify uptrim has occurred at 400 ft...", and I'm convinced some people won't even notice the lack of it.
And now the pilots aspect: how much do we want to trust them?
Why do two pilots need an uptrim if two autopilots, two red disconnect lights, an aural warning, a stab out of trim, and their ability to pull up manually are not enough to avoid making a large hole into the runway, when the same pilots are legally allowed to manually land an airplane after a CAT II approach with a visual segment available as low as fifteen metres?
XXXX
One important clarification: I said my decision was to land after the no uptrim event, not that I actually landed.
In fact, after the ramark of the boss, I did go around at more or less 250 ft.
There still was no STAB OUT OF TRIM light.
And I've got the impression that it doesn't come on, if the uptrim doesn't take place.
So, of course, if the light actually comes on, maybe at a later stage, this whole thread is invalid, although quite interesting and stimulating...
But if it doesn't, I think my points deserve some attention...
XXXX
Regarding the "rewarding" question, I just laugh at people considering it machismo.
I do confirm, yes, I'm rewarded when I safely land in "difficult" conditions.
Landing in CAT II or III is more difficult than landing in good weather. That's why not everybody can do it. One need to be qualified. It goes by itself.
So that's rewarding for everybody.
But in openly saying that, I make the other narcissist guys feel uncomfortable, as they think only they can secretly be rewarded.
Narcissism wears all sort of masks and garnments, including the humility one.
Know the little joke of the old man about to pass over, all his relatives and friends around his bed enumerating his virtues?
Eventually, he raises and says: " You have forgotten my humility!"
But... who cares!!
I'm a pilot, not a politician, nor a demagogue, as somebody on this forum.
When I mean bread I mean bread, when I mean wine I mean wine.
So, enough blah blah and back on stage!
XXXX
I'll start by quoting my LOW VISIBILITY OPERATIONS MANUAL:
"If, during a CAT III approach, a system failure occurs which requires intervention by the pilot, a go around will be performed, unless the aircraft is below DH and the Captain has adequate visual reference to complete a manual landing."
Also: "If a system malfunction or engine failure occurs below DH, the Captain may, provided adequate visual references exist, continue the approach and land manually."
(Italic is mine).
Some posters have expressed their concernment about manually landing in poor visibility, accusing me of machismo, disconcerting attitude, pushing the airplane beyond its limitations and rubbish like that.
I thought that legally meant safely, in aviation.
Have you ever realized we are allowed lo legally land with a 15mtrs visual segment, although displaced due to the slant visual range?
Yes, FIFTEEN METRES!
Disconcerting, isn't it?
How come 15 mtrs?
My book says: if after passing the OM or equivalent position the RVR decreases to below minimums, the pilot is allowed to continue down to the radio minima, and land if he is satisfied with the visual cues.
Now, once again, adequate visual cues means THREE longitudinal lights, i.e. THREE runway centreline lights, which can be spaced as close as seven and a half metres!
That gives a segment of 15 metres!
And, just to add to the fun, all this is perfectly valid in CAT II, with the addition of one lateral element, being one TDZ barrette.
Correct me if I'm wrong with all this math, but CAT II means manual landing !
Now, I understand some decades ago the idea of an airplane landing by itself was unbelievable to the general public, so I understand how people involved with the certification process have tended to cover their *** as much as they could.
So, as a last resort, if everything goes to worms and our pilots are sleeping, let's give us a last chance adding this uptrim which will prevent making a big hole into the runway.
Fine.
So now I've got at least two questions: why isn't there a warning if uptrim doesn't occur?
Why don't we have a callout for that? And why in the long and detailed list of all the required working components - and downgradable ones - there is no mention at all about uptrim?
In my manuals I cant't find anything about "... verify uptrim has occurred at 400 ft...", and I'm convinced some people won't even notice the lack of it.
And now the pilots aspect: how much do we want to trust them?
Why do two pilots need an uptrim if two autopilots, two red disconnect lights, an aural warning, a stab out of trim, and their ability to pull up manually are not enough to avoid making a large hole into the runway, when the same pilots are legally allowed to manually land an airplane after a CAT II approach with a visual segment available as low as fifteen metres?
XXXX
One important clarification: I said my decision was to land after the no uptrim event, not that I actually landed.
In fact, after the ramark of the boss, I did go around at more or less 250 ft.
There still was no STAB OUT OF TRIM light.
And I've got the impression that it doesn't come on, if the uptrim doesn't take place.
So, of course, if the light actually comes on, maybe at a later stage, this whole thread is invalid, although quite interesting and stimulating...
But if it doesn't, I think my points deserve some attention...
XXXX
Regarding the "rewarding" question, I just laugh at people considering it machismo.
I do confirm, yes, I'm rewarded when I safely land in "difficult" conditions.
Landing in CAT II or III is more difficult than landing in good weather. That's why not everybody can do it. One need to be qualified. It goes by itself.
So that's rewarding for everybody.
But in openly saying that, I make the other narcissist guys feel uncomfortable, as they think only they can secretly be rewarded.
Narcissism wears all sort of masks and garnments, including the humility one.
Know the little joke of the old man about to pass over, all his relatives and friends around his bed enumerating his virtues?
Eventually, he raises and says: " You have forgotten my humility!"
Some observations on LEM’s post.
From my experience there is very little in aviation that is legally sound; the best course of action is “to do, and be seen to do” the correct thing for the circumstance i.e. take the safest option. With this in mind, it would be preferable for an operator to have SOPs for those abnormal circumstances where the captain has to satisfy himself with the visual cues e.g RVR below minima after OM.
Specific policy/procedures should define less restrictive visual cues in the event of a system failure; e.g to aid the crew in aligning or correcting a deviation resulting from an engine failure. In the event of an incident, it is more difficult for an individual to show that the required level of expertise existed or that correct judgement was made in the circumstances, as opposed to using a careful pre considered SOP to cover such situations – a task for management.
The visual segment maths are fine, providing all runways have closely spaced lighting. In addition, I think that you have identified a weakness in the JAR-OPS wording which was drafted before the wider use of closely spaced ‘Cat 3b’ lighting. The initial draft of subpart E required use of minimum visual segments as determined by experimental flight trials (ECAC Doc 17). I recall that for Cat 2 manual landing, this was 250 m, but as the old 400m RVR limit has been reduced to 350/300m RVR, the vis seg may now be 225 – 180 m depending on aircraft type. The first point of contact and duration with the visual references are important aspects in assessing the aircraft flight path and alignment.
Cat 3 autoland required a smaller visual segment at 50 ft (90 m), approx 3 consecutive sets of ‘lights’. However, as the smaller ‘autoland’ visual segment would not give an equivalent level of safety for a manual landing (without guidance, HUD, etc), JAR-OPS Interpretive and Explanatory Material (IEM) suggests a GA for any failure above DH in RVR less that 300 m, but the wording is loose enough to allow manual landing below DH.
A good explanation of the relationship between RVR, visual segment, and slant visual range is given in the Airbus document Getting to grips with Category II and III Operations.
Re RVR falling below the approach ban limitations. In stable fog conditions, typical of Cat 3, any change in RVR with time is normally very small. However, for blowing snow or dust then the change could be large and indicate weather conditions to avoid.
In Cat 2, the RVR is more variable due to fog forming or clearing. Even a ‘normal’ Cat 2 decision can turn out to be wrong if cloud or fog banks blow across the runway, thus ‘legality’ before or after DH, still requires good crew judgement. This means taking the safest option, which ideally has been well thought through on the ground and thus less likely to suffer human error in an unfamiliar airborne scenario.
Finely, the thread – uptrim. Most systems, such as uptrim are in an aircraft for a good reason; if they are important to safety there should be a warning or physical limit, although in older aircraft the manufacturers relied on a crew procedure. If the reason for the equipment is not known, then avoid making assumptions about any operation if it fails.
Thus, does the 737 have a light, limit, or procedure for no uptrim or system failure?
From my experience there is very little in aviation that is legally sound; the best course of action is “to do, and be seen to do” the correct thing for the circumstance i.e. take the safest option. With this in mind, it would be preferable for an operator to have SOPs for those abnormal circumstances where the captain has to satisfy himself with the visual cues e.g RVR below minima after OM.
Specific policy/procedures should define less restrictive visual cues in the event of a system failure; e.g to aid the crew in aligning or correcting a deviation resulting from an engine failure. In the event of an incident, it is more difficult for an individual to show that the required level of expertise existed or that correct judgement was made in the circumstances, as opposed to using a careful pre considered SOP to cover such situations – a task for management.
The visual segment maths are fine, providing all runways have closely spaced lighting. In addition, I think that you have identified a weakness in the JAR-OPS wording which was drafted before the wider use of closely spaced ‘Cat 3b’ lighting. The initial draft of subpart E required use of minimum visual segments as determined by experimental flight trials (ECAC Doc 17). I recall that for Cat 2 manual landing, this was 250 m, but as the old 400m RVR limit has been reduced to 350/300m RVR, the vis seg may now be 225 – 180 m depending on aircraft type. The first point of contact and duration with the visual references are important aspects in assessing the aircraft flight path and alignment.
Cat 3 autoland required a smaller visual segment at 50 ft (90 m), approx 3 consecutive sets of ‘lights’. However, as the smaller ‘autoland’ visual segment would not give an equivalent level of safety for a manual landing (without guidance, HUD, etc), JAR-OPS Interpretive and Explanatory Material (IEM) suggests a GA for any failure above DH in RVR less that 300 m, but the wording is loose enough to allow manual landing below DH.
A good explanation of the relationship between RVR, visual segment, and slant visual range is given in the Airbus document Getting to grips with Category II and III Operations.
Re RVR falling below the approach ban limitations. In stable fog conditions, typical of Cat 3, any change in RVR with time is normally very small. However, for blowing snow or dust then the change could be large and indicate weather conditions to avoid.
In Cat 2, the RVR is more variable due to fog forming or clearing. Even a ‘normal’ Cat 2 decision can turn out to be wrong if cloud or fog banks blow across the runway, thus ‘legality’ before or after DH, still requires good crew judgement. This means taking the safest option, which ideally has been well thought through on the ground and thus less likely to suffer human error in an unfamiliar airborne scenario.
Finely, the thread – uptrim. Most systems, such as uptrim are in an aircraft for a good reason; if they are important to safety there should be a warning or physical limit, although in older aircraft the manufacturers relied on a crew procedure. If the reason for the equipment is not known, then avoid making assumptions about any operation if it fails.
Thus, does the 737 have a light, limit, or procedure for no uptrim or system failure?
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Hey safetypee,
No light and no (hands on) procedure.
This means in case of two failures (1. No 400ft uptrim. 2. Flare doesn't engage (green)), your MANUAL landing (see my previous post) will be a lot harder than expected and hopefully on the main gear first.
Conclusion : Why not make the 400ft uptrim an OFFICIAL check ? And clearly state if a go-around is required or not.
Hey error 401,
There is no law saying to go-around for ANY FAILURE during a CAT III. Failures which don't affect your approach and if you are FULLY AWARE of the situation, you may continue. No fidling at low altitude of course.
No light and no (hands on) procedure.
This means in case of two failures (1. No 400ft uptrim. 2. Flare doesn't engage (green)), your MANUAL landing (see my previous post) will be a lot harder than expected and hopefully on the main gear first.
Conclusion : Why not make the 400ft uptrim an OFFICIAL check ? And clearly state if a go-around is required or not.
Hey error 401,
There is no law saying to go-around for ANY FAILURE during a CAT III. Failures which don't affect your approach and if you are FULLY AWARE of the situation, you may continue. No fidling at low altitude of course.
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Alaskan,
Thanks for the answer. It was exactly meant as posted by safetypee and as you said. I was wondering "if" your OM would state something (than it would become a legal issue). Safetypee gave a nice answer in his post - that is a management thing to define an SOP including failing systems.
Thanks for the answer. It was exactly meant as posted by safetypee and as you said. I was wondering "if" your OM would state something (than it would become a legal issue). Safetypee gave a nice answer in his post - that is a management thing to define an SOP including failing systems.
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hello every one,
cfr this uptrim business at 400ft for b737classic in a 2 autopilot cat3 approach i think we should keep it as simple as possible: if it is not somewhere necessary on safety grounds or not required by reg's, be assured mr boeing or any other airplane manufacturer would not go over to the trouble of designing/certifying this feature on cost grounds alone.
so, i would consider the lack of uptrim at 400ft, if noticed, a failure of the integrity of the automatic gizzmo's & unwilling to be in for some unexpected nasty surprises during subsequent flare/landing when least needed(cat3 wx conditions): would call something like:"no uptrim, go-around", disconnect the autopilots, push toga & do a manual go-around as per sop's an automatic go-around would only be performed on weather considerations only: eg. not enough visual cues at dh.
but i agree, it looks a strange & mystery failure.
cfr this uptrim business at 400ft for b737classic in a 2 autopilot cat3 approach i think we should keep it as simple as possible: if it is not somewhere necessary on safety grounds or not required by reg's, be assured mr boeing or any other airplane manufacturer would not go over to the trouble of designing/certifying this feature on cost grounds alone.
so, i would consider the lack of uptrim at 400ft, if noticed, a failure of the integrity of the automatic gizzmo's & unwilling to be in for some unexpected nasty surprises during subsequent flare/landing when least needed(cat3 wx conditions): would call something like:"no uptrim, go-around", disconnect the autopilots, push toga & do a manual go-around as per sop's an automatic go-around would only be performed on weather considerations only: eg. not enough visual cues at dh.
but i agree, it looks a strange & mystery failure.
