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What are the problems with FDs?

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What are the problems with FDs?

Old 13th May 2013, 05:21
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"The reason is, if you are in open descent and disconnect the AP and pull back for a TCAS RA no thrust will increase, your speed will bleed off and you wont climb very far. Turning off both FDs puts the autothrust into speed mode so as you pull back the thrust will increase"

Ding, ding, ding.

Winner here!!
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Old 13th May 2013, 05:39
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Gosh i love boeing....
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Old 13th May 2013, 10:04
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Children of the Magenta, indeed, `tis true.

Thank you all for your time and input. My question (as usual poorly written) was intended to see if there were many inherent bugs or bogies with FDs in general.

Specifically however, the A320 FDs - so the feedback you have given me on the A320 systems is invaluable and I thank you very much and I will have to get yet even deeper into the AOM and the autothrust system. Especially the autothrust system.

On the magenta line. Once I wondered if I could Heading Sel as BOAC suggested to get my L1011 to work on the minimum of auto, as, bascially, I did not want to f--k about with it. So, we hand flew to cruise and we were very happy. After a major conference in crz to determine that everything is tickety boo as per the plan - then we would select A/P on, and if it did what it was meant to then we would continue to TOD where we we did the same thing in reverse.

I studied, at that time the levels of automention 1,2,3, etc or a,b,c, depending on which school.

Now, with Glass and FBW - as one company puts it - "you will be assimilated" and it is true - in order to properly understand the thing, you have to be a part of it, engrossed though I am there are others who are totally and absolutely technotroids, but you have to be if you are to understand the system like one or two on here do . . . (far more than me (but I am catching up . .!)

Simply put, if I don`t get totally into it then I won`t know why it has just killed me. Not wishing to die and glad of previous experience of different levels of automation to a point where "if it aint doing what we want now then we`ll fly it another way"
downgrade,
dowgrade,
until we are hand flying the thing. Basic stick and rudder stuff Wright brothers?
Well, to a point.

L1011 was a babe to fly hands on, probably the best aircraft ever built.
The airbus will be equally easy and flyable manually, once the techtronic/human decider valve (in my human brain) has disconnected me (as a mere tie connector) from the machine.

Last edited by Natstrackalpha; 13th May 2013 at 10:33.
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Old 13th May 2013, 14:29
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FD's OFF

Base turn to final, and in a descent. Called for FD's to OFF. Captain turns his FD off, co-pilot leaves his on....Aircraft autothrust selects TOGA, and we begin accelerating into the ground.


That is why you should both turn off, or both leave on the FD's
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Old 13th Jun 2013, 06:19
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I will share with you, my recent experience, on B777 climbing out of FL 187 Cleared for FL250, light weight aircraft, about 60 kts head wind, experiencing mod turbulence, so speed was reduced from 310 kts to turb penetration 270 kts, the airplane had a ROC as a result of speed reduction/head wind/light wieght to 6000ft/min

The airplane went into VNAV ALT Mode while passing FL190, which meant the capture phase began at FL190, the pitch mode of the aircraft (as indicated by FD) focussed on capturing FL250, the thrust lever changed to spd mode, once the speed dropped below 270 kts, the airplane wouldnt pitch down because the pitch att was stuck to capture FL250, the climb power then became less to maintain 270 kts as shown by the downward trend on speed.

The a/c had to be changed to V/S mode, to reduce pitch, straight away, and since this was anticipated, nothing went wrong, but FD went into capture phase because the FMC logic was such, this could have resulted into a complicated situation, so this is one case, where FD taking inputs from FMC in a case like this, would have managed to bring the airplane to low speed buffet before having a mode reversion to VNAV SPD again, which would have taken lot of time to actually recover, considering the airplane trim was in support of nose up while it was in VNAV ALT.
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Old 13th Jun 2013, 09:23
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Seems like a really good reason not to be doing anything but watching what George or Otto is doing when being so dynamic; plus knowing what it should be doing and what you want it to do and knowing how to resolve the two. Seems like you did.


I've seen other scenarios where the A/P was not doing what Freddie in RHS wanted, so they started playing the piano on the MCP trying to correct it, then in desperation disconnected to sort it out. That's quite a healthy outcome; not being afraid to take charge, but it still showed a weak understanding of how to have avoided or corrected the situation via the MPC in the first place.

Therein lies a weakness in training. Cadets are taught how to use the MCP in standard scenarios like trained monkeys, and usually the FD follows their actions. They are not told how to use the MCP in depth and so can choose what to do to achieve the wanted result. Don't learn only one tune but learn all the scales.

Regarding the FD the scan has been diluted to "follow the FD." Many scenarios have been quoted where the FD was wrong or confusing, e.g. FD fly right, LOC deviation left. Scanning the ND for S.A. & W/V, ADF needles etc. resolved what was happening, but the dogmatic following of FD in such circumstances caused confusion with PF and a little consternation within me as PM that the PF was not using all the information available but was tunnelled vision on the FD.
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Old 13th Jun 2013, 10:29
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If the automation is not doing what you want it to do, take the auto pilot out and hand fly it. Everything gets very simple, very quickly. This holds true for Airbus or Boeing.

Automation is ment to reduce workload, the moment it starts to increase it, its time to start ditching it. The problem is recognising that moment.
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Old 13th Jun 2013, 11:38
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RAT 5
Airbus goldenrule 2.
2.Use the appropriate level of automation at all times.
•The appropriate level of automation depends upon the situation and the task. Pilot judgment prevails, including selecting manual flight.
•Understand the implication of the intended level of automation.
•Select the intended level.
•Confirm the expected aircraft reaction
Glden rule 4
4. Take action if things do not go as expected
. By PF changing the level of automation.
. By PF reverting to manual flight.
. By PNF taking action,
.Question.
Challenge.
Take-over.

 

Last edited by vilas; 13th Jun 2013 at 11:41.
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Old 13th Jun 2013, 12:10
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. By PNF taking action,
.Question.
Challenge.
Take-over.
All very fine if you have a compliant captain who is more than willing to hand over control meekly when his 240 hour support pilot grabs the controls.
But if the captain asserts his command authority backed by the Regulations, and tells the lad to bugger off and handle the radios, then the mantra of Question, Challenge, Take Over is yet another motherhood statement written by the gurus of the CRM tribe. I have yet to see any official guidance from a Regulator or any other authority on the specific method a first officer is supposed to fall back on to physically take command of the aircraft.
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Old 13th Jun 2013, 13:01
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Centaurus
Didn't you read comments on Air India express crash at Mangalore? So many guys blamed cockpit gredient and Asian culture and suggesting that FO should have been more aggressive. This perticular accident it was so necessary that it was better to loose the licence than life. However life is rarely in black and white more often it is shades of grey. That is where real problem arises and I agree with you there. However a culture needs to be built in an Airline where captain should feel that willful violations of SOPs will be met with resistance. I got the impression that it already exists in western society. It is becoming more difficult as the level of experience of the FO is progressively brought down where the experience gradient has become steep.
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Old 13th Jun 2013, 13:33
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All very fine if you have a compliant captain who is more than willing to hand over control meekly when his 240 hour support pilot grabs the controls.
But if the captain asserts his command authority backed by the Regulations, and tells the lad to bugger off and handle the radios, then the mantra of Question, Challenge, Take Over is yet another motherhood statement written by the gurus of the CRM tribe. I have yet to see any official guidance from a Regulator or any other authority on the specific method a first officer is supposed to fall back on to physically take command of the aircraft.
Crash axe or fire extinguisher, which ever comes to hand first.
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Old 13th Jun 2013, 13:49
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To Agg Karan:

Interesting experience that you share with us. Please research the following link, you will see that history repeats itself and it is the sharing of experiences like you just did, that may prepare others to react properly and timely when it is their time to deal with a like occurrence.

Use Google to search for
Transport Safety Board of Canada AVIATION INVESTIGATION REPORT
A04O0020

or use this direct link

Transportation Safety Board of Canada - Aviation Investigation Report A04O0020

Safe flying to you!

To people who still think that certain things happen only to Airbusses and not to Boeings, a few quotes to capture their attention ...

Quote
The autopilot pitched the aircraft up to 29.5º in an attempt to maintain the ALT CAP profile and, as a result, the airspeed decreased further. This attitude was maintained until the stick shaker activated and the flight crew took recovery action.

Other finding:
The autopilot was functioning as designed during the occurrence.
Unquote

Proper understanding and use of automation is required on all types of aircraft.

Last edited by EMIT; 13th Jun 2013 at 14:05.
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Old 13th Jun 2013, 14:12
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Automation

Thank you for the appropriate example.
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Old 13th Jun 2013, 14:30
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de facto
Any comments from you on Boeing on EMIT's blog no.32 or love is blind?
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Old 13th Jun 2013, 15:23
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You might notice that defacto was posting in reply to the peculiar FD problem on airbus aircraft. And yes, in that regard the boeing is much more simple. Doesn't matter at all if one FD is on, both, or none, in both manual and automatic flight.

The ALT CAP thing is usually not a problem with proper training, its demonstrated once during the initial typerating and then each pilot uses one of several methods that prevents it. However, it is an autoflight issue and not a FD one.
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Old 13th Jun 2013, 16:41
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Denti,

With regards to "it" being an autoflight thing and not an FD thing - the flight director is the visual depiction of what the pilot should do to follow the same path as the autopilot would follow.
So, the FD would have seduced a slavish follower down the same primrose path to a stall. The only giveaway would have been the removal of the pitch bar from the display - and an Airbus would also have done that (re. the AF447 report, FD disappearing and re-appearing)

As far as autothrust is concerned - if you descend in FLCH and do not follow the FD pitch commands (such as during a TCAS CLIMB event), the autothrust will not increase thrust to keep speed constant, it will still indicate FLCH or THR HLD in the FMA (it "thinks" that the FD pitch mode is taking care of the speed).

A problem noted by the Canadians was that pilots routinely do not know all the possible autoflight/FD symptoms, such as diasappearance of bars, amber lines through FMA modes, etcetera, which may also differ from mod to mod status, because one "never" operates on those edges of the envelope.
However, abiding by the simple rule, if the aircraft does not do what you want it to do, grab control (physically do it yourself with stick, rudder and throttle) solves all problems.
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Old 13th Jun 2013, 17:10
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However, abiding by the simple rule, if the aircraft does not do what you want it to do, grab control (physically do it yourself with stick, rudder and throttle) solves all problems.
Indeed, and it might even work on an airbus.

The ALT CAP thing is something we encounter a lot, especially in out -700s. Those are quite often light weight and climb rates in excess of 4000fpm up into the mid 300s are normal, which can preclude the reduced rate in the last 1000ft before level off since ALT CAP becomes active too early. Simple thing to do if one doesn't want to disconnect the autopilot is to push the yoke a bit, CWS will work just fine. Disconnecting the AP works just as well of course.
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Old 13th Jun 2013, 17:31
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Yeah Denti, I recognise the situation.

Another simple rule of thumb - climb rate not more than altitude difference, i.e.4.000 ft to go, V/S no more than 4.000 ft/min, 3.000 ft to go V/S 3.0000 and so on and switch to V/S mode if climb rate of VNAV (or similar mode) does not respect that schedule.
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Old 13th Jun 2013, 18:17
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Base turn to final, and in a descent. Called for FD's to OFF. Captain turns his FD off, co-pilot leaves his on....Aircraft autothrust selects TOGA, and we begin accelerating into the ground.

That is why you should both turn off, or both leave on the FDs!
If that's happened on an A320 series you've got something else wrong. The autothrust can't 'just' select TOGA it has to be in response to something else. So, what's the other bit of this story.....
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Old 13th Jun 2013, 20:17
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However, abiding by the simple rule, if the aircraft does not do what you want it to do, grab control (physically do it yourself with stick, rudder and throttle) solves all problems.

Proper understanding and use of automation is required on all types of aircraft.


Wonderful. I think this debate is going round in circles and has ended up where it was some years ago prompted by other threads. 1st point is a training/experience issue, but sadly due to lack of training it might increase problems. But that should not be the case.

2nd point is also a training issue and has not been addressed by the XAA's or companies. I've been involved for many years in TQ training. The change that the customers have introduced is minimum sim training time to pass LST due to self payment versus training to a higher standard than LST. I do not know what standard they train manual flying to on the line, but the reports of incidents on here lead me to suspect not very high.

In some companies there has definitely been a philosophy to reduce the amount of stick & rudder use on the line due to cock ups. This is the attitude of "if they don't know what they are doing, or don't know how to to, then don't let them do it." IMHO this is an accident looking for a place to happen. Sometime, something will go wrong. The sharp end jockeys need to be able to sort it out. The pax expect this. I wonder if the XAA"s do? Not everything is in a QRH. Often some lateral out of the box thinking is required to save the day. The sort of thing a 'cabin attendant' could not sort out....if you get my drift. The sort of thing we should be educated in every 6 months, not the routine boring trained monkey stuff. After 30 years if I can't handle a V1 cut I should be driving the crew bus, if there was one. I've done it 60 times in a sim. The OPC/LPC is in need of a reality check. You know you are going to get a SE G/A from a SE ILS. There is no surprise. You know you are going to get an RTO. Surely there needs to be some reality/surprise introduced into the prof' checks. The 6 month merry-go-round is not such a sure method of maintaining standards. It's a tick in the box and I've seen some lax application of pass criteria in my time.

The more the companies decide that we need to be just button pushers the more they will train to that idea. Then they will write such comprehensive SOP's as to make us robotic trained monkeys. Then they can pay us peanuts to sit in the sun all day. It's a great conspiracy, and it's happening in an airline near you.
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