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Flight Directors - a sometimes fatal attraction

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Flight Directors - a sometimes fatal attraction

Old 2nd Feb 2013, 11:00
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Flight Directors - a sometimes fatal attraction

My first encounter with flight directors was in 1966 while undergoing conversion to the Avro 748. The RAAF had seen fit to send me to Woodford in Cheshire, all the way from Australia to ferry the second of several new 748’s for the RAAF VIP squadron at Canberra. The conversion was conducted on a battered 748 demonstrator G-ARAY known as Gary. The contract allowed four hours of dual for the captains and nothing for the co-pilots. G-ARAY had the basic instrument flying panel of that era and no flight director. Our instructors at Avro’s were well known test pilots Bill Else, Tony Blackman and Eric Franklin. Jimmy Harrison was chief test pilot.

Unlike the bog-standard civilian 748, the RAAF 748’s were to be equipped with a Collins FD 108 FD. So the situation existed that the RAAF 748’s had a British Smith’s autopilot system which was married (somewhat expensively and painfully) to the American Collins FD 108. For the life of me I could not see why a flight director was needed in the RAAF 748. After all, the approach speed was that of a DC3 – 80 knots and the aircraft a delight to handle compared with the venerable Dak.

In retrospect, I think the old Wing Commander Transport Ops at Department of Air, who was charged with the procurement of the 748 for RAAF service, and hadn’t flown for years, was perhaps conned by the Avro sales people in conjunction with Collins, into buying the Collins systems. Certainly in my view as the squadron QFI, flight directors were not operationally needed. In the event, the RAAF machines came with Collins FD 108 flight directors and as the contract specified each captain would be given only one hour of dual instruction once the 748 came out of the factory, we needed to learn how to operate the FD.


First, a course was arranged at the Collins establishment at Weybridge in Surrey. The two RAAF captains and their co-pilots attended and our two navigators and our instrument fitters also turned up to enjoy the Collins hospitality. We learned about 45 degree automatic intercepts of the VOR and ILS beams and other goodies including V-bar interpretation. We were showered with glossy brochures of the flight director by white dust-coated lecturers and shown a film. By lunch time the presentation was complete and we were shouted to a slap up pub meal with lots of grog, all paid for by Collins. We asked what further lectures were to take place after lunch. We were told the course was over – it was just a morning’s job and we were free to leave unless we would like more drinks.

Naturally it was churlish to refuse and hours later we staggered to the railway station (I think), smashed to the eye balls and having forgotten all about the marvels of 45 degree auto intercepts on the FD 108. I must say it was a bloody good three hour course what with the free grog and all that.

A few weeks later, I flew the second RAAF aircraft out of the factory, A10-596, under the watchful eye of Eric Franklin DFC and he demonstrated flight director stuff. For example to climb using the FD, you first put the aircraft into a normal climb and when settled you switched on the FD and carefully wound up the pitch knob so that the little aeroplane sat in the middle of the V-bars. I quickly realised that you hand flew the basic artificial horizon to whatever attitude was appropriate for the manoeuvre then told the FD 108 V bars where you wanted them. The ILS intercept of 45 degrees was never used because radar vectors didn’t do such angles. I became more and more convinced the 748 didn’t need flight directors and that they were a load of bollocks in that type of low speed aircraft.

We were told the USAF used the FD 108 in its F4 Phantoms and that Collins was anxious to makes sales in the UK market. The RAAF Wing Commander got sucked in by good sales talk and from then on all RAAF 748’s became so equipped. I held personal doubts about the usefulness of flight directors in general as I could see even then, their extended use could lead to degradation of pure instrument flying skills. Today’s flight director systems are light years ahead in sophistication compared with the old Collins FD 105 and 108 series. But the problem with blind reliance on FD indications and thus steady degradation of manual instrument flying skills is as real now as it was back in 1966.

Now to the present day - although first some background history. First published in 1967, “Handling the Big Jets” written by the then British Air Registration Board’s chief test pilot David Davies, is still considered by some as the finest treatise still around on jet transport handling. Indeed, the book was described by IFALPA as `the best of its kind in the world`…written by a test pilot for airline pilots, the book is likely to become a standard text book…particularly recommended to all airline pilots who fly jets in the future…valuable to those pilots who are active in air safety work”.

All that was back in 1967 and little has changed since then - apart from an increasing propensity for crashes involving loss of control rather than simply running into hills. LOC instead of CFIT. Mostly these accidents were caused primarily by poor hand flying and instrument flying skills which certainly explains why aircraft manufacturers lead the push for more and more automatics. A colleague involved with Boeing 787 training was told by a test pilot on type, that the 787 design philosophy was based on the premise that incompetent crews would be flying the aircraft and that its sophisticated automatic protection systems were in place to defend against incompetent handling. Be it a tongue-in-cheek observation or not, it contains an element of truth. With the plethora of inexperienced low hour cadet pilots going directly into the second in command seats in many airlines in Asia, the Middle East and Europe, these protection systems are important.

Towards the end of his book, David Davies discusses the limitations of the flight instruments in turbulence and in particular the generally small size of the active part of the basic attitude information or the ‘little aeroplane” as many older pilots will remember it. He continues: “the preponderance of flight director and other information suppresses the attitude information and makes it difficult to get at” and “the inability, where pitch and roll information is split, to convey true attitude information at large pitch and roll angles in combination” Finally, Davies exhorts airline pilots “not to become lazy in your professional lives…the autopilot is a great comfort, so is the flight director and approach coupler…but do not get into the position where you need these devices to complete a flight”. There is more but go and read the book.

Having done the unforgiveable and quoted freely from an eminent authority, it is time for Centaurus to say something original and accept the no doubt critical comment that is freely available on PPRuNe. Flight Directors can be a fatal attraction to those pilots who have been brain-washed by their training system to rely on them at all times. While Boeing in their FCTM advise pilots to ensure flight director modes are selected for the desired manoeuvre, it also makes the point that the FD should be turned off, if commands are not to be followed.

Recently a new pilot to the Boeing 737 asked his line training captain if he could turn off the FD during a visual climb so he could better “see” the climb attitude. His request was refused as being “unsafe” and instead he was told to “look through” the FD. I don’t know about you, but I find it impossible to “see” the little aeroplane when it is obscured by twin needles or V-bars. In fact it takes a fair amount of imagination and concentration to do so. Which may be why Boeing recommends pilots to switch off the FD if commands are not to be followed.

I well recall my first simulator experience in the 737 of an engine failure at V2 where I was having a devil of a time trying to correct yaw and roll and the instructor shouting at me to “Follow the bloody flight director needles”. I learned a good lesson from that tirade of abuse on how not to instruct if ever I became a check pilot. In later years, having gravitated to the exalted – or despised maybe – role of simulator instructor, my habit was to introduce the engine failure on take-off by first personally demonstrating to the student how it should be done on raw data; meaning without a flight director. I hoped by first demonstrating, the student could see the body angles or attitude rather than imagine them by trying to “look through” the dancing needles of the FD. I have always been an advocate of the Central Flying School instructional technique of demonstrate first so the student then knows what is aiming for. Of course in the simulator, the instructor runs the risk of stuffing up (been there - done that!) but it at least proves he is human and not just another screaming skull.

Recently, a 250 hour pilot with a type rating on the 737-300 and trained overseas, booked a practice session prior to putting himself up to renew an instrument rating. His last rating was on a B76 Duchess. As part of the 737 instrument rating would include manual flying on raw data, he was given a practice manual throttle raw data take off and climb to 3000 ft. He protested, saying he had never flown the simulator without the flight director. His instructions were to maintain 180 knots with Flaps 5 on levelling. He was unable to cope and when the instructor froze the simulator to save more embarrassment, the student was 2000 ft above cleared level and 270 knots still accelerating with take off thrust. The student had been totally reliant on following flight directors with their associated autothrottles during his type rating course and without this aid he was helpless. I believe this is more widespread than most of us would believe; especially as we tend to move in our own narrow circle of experience.

At a US flight safety symposium, a speaker made the point that it is the less experienced first officers starting out at smaller carriers who most need manual flying experience. And, airline training programs are focused on training pilots to fly with the automation, rather than without it. Senior pilots, even if their manual flying skills are rusty, can at least draw on experience flying older generations of less automated planes.

On 4 January this year, the FAA published a Safety Alert for Operators (SAFO) entitled Manual Flight Operations. The purpose of the SAFO was to encourage operators to promote manual flight operations when appropriate. An extract from the SAFO stated that a recent analysis of flight operations data (including normal flight operations, incidents and accidents) identified an increase in manual handling errors and “the FAA believes maintaining and improving the knowledge and skills for manual flight operations is necessary for safe flight operations.” Now let me see, I recall similar sentiments nearly 50 years ago published in “Handling the Big Jets” when David Davies wrote ” that airline pilots should “not become lazy in your professional lives…the autopilot is a great comfort, so is the flight director and approach coupler but do not get into the position where you need these devices to complete the flight.” See my earlier paragraphs.

It is a good bet that lip service will be paid by most US operators to the FAA recommendation to do more hand flying. It may have some effect in USA but certainly the majority of the world’s airlines, if they were even aware of the FAA stance in the first place (very doubtful), will continue to stick with accent on full automation from lift off to near touch-down and either ban or discourage their pilots from hand flying on line. If you don’t believe that, consider the statement in one European 737 FCOM from 20 years ago that said: “Under only exceptional circumstances will manual flight be permitted”

After all, when at least two major airlines in SE Asia have recently banned all take off and landings by first officers because of their poor flying ability, then what hope is there to allow these pilots to actually touch the controls and hand fly in good weather? One of those airlines requires the first officer to have a minimum of five years on type before being allowed to take off or land while the other stipulates the captain will do all the flying below 5000 ft. It might stop QAR pings and the captain wearing the consequences of the first officer’s lack of handling ability, but it sure fails to address the real cause and that is lack of proper training before first officers are shoved out on line.

I think the FAA missed a golden opportunity in its SAFO to note that practicing hand flying to maintain flying skills will better attain that objective if flight director guidance is switched off. The very design of flight director systems concentrates all information into two needles (or V-bar) and in order to get those needles centred over the little square box, it needs intense concentration by the pilot. Normal instrument flight scan technique is degraded or disappears with the pilot sometimes oblivious to the other instruments because of the need to focus exclusively on the FD needles. Believe me we see this in the simulator time and again. Manual flying without first switching off FD information will not increase basic handling or instrument flying skills.

The flight director is amazingly accurate provided the information sent to it is correct. But you don’t need it for all stages of flight. Given wrong information and followed blindly, it becomes a fatal attraction. Yet we have seen in the simulator a marked reluctance for pilots to switch it off when it no longer gives useful information. Instructors are quick to blame the hapless student for not following the FD needles. This only serves to reinforce addiction to the FD needles as they must be right because the instructor keeps on telling them so. For type rating training on new pilots, repeated circuits and landings sharpen handling skills. Yet it not uncommon for instructors to teach students to enter waypoints around the circuit and then exhort the pilots “fly the flight director” instead of having then look outside at the runway to judge how things are going.

First officers are a captive audience to a captain’s whims. If the captain is nervous about letting his first officer turn off the flight director for simple climbs or descents, or even a non-threatening instrument approach, then it reflects adversely on the captain’s own confidence he could handle a non-flight director approach. The FAA has already acted belatedly in publicly recommending that operators should encourage more hand flying if conditions are appropriate. But switch off the flight directors if you want real value for money particularly with low hour pilots. It may save lives on the proverbial dark and stormy night and the generators play up.
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Old 2nd Feb 2013, 11:47
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I agree that flying manually with the FD on is a meaningless exercise.
Last week my fo when descending through around 6000 ft advised me he was about to disconnect the AP and fly manually with AT off.
I advised back that if he wanted to fly it would be with those FD off,to at least make his neurons and scan work,he agreed and off he went.
Got a bit air sick but with a bit of coaching he landed safely.(realized that homing an ILS was possible)
After landing he advised me it was the first time he ever did it in 3 years and i replied next time we will do it again with less homing hopefully..

As we both enjoyed it,I decided to do the takeoff without fd and AT and the arrival the same way,was enjoyable even with the Chinese QAR monitoring...

Last edited by de facto; 2nd Feb 2013 at 11:50.
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Old 2nd Feb 2013, 12:23
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I agree with your posts. However it is easily possible to fly "through" the flight director, especially upon take off and initial climb. It is a very useful exercise. You simply need to rotate to your anticipated pitch, check your expected speed trend (more or less 0) and then adjust this pitch throughout the thrust reduction and the clean up.
You will more often than not see the aircraft symbol nicely because the flight director will need a few moments to complete its "dolphin movements" and show different, until it has established its computations and, if you got your part right and smooth, finally joined your attitude. Then you can engage the autopilot. If you do it nicely, the passengers will thank you because you will have settled into a very small and comfortable pitch variance throughout your manoeuvring, as opposed to when you'd follow the FD through its initial interpolations between max and min pitch oscillations .....

The same applies during approach. Manual flying with the FD once configured is easy and has no learning effect. You can leave the FD on, but dirty-up the plane yourself with anticipated pitch changes. Once again the FD will catch-up with you once nicely established and in F-class the PITA's will have been able to sip their last coffee without spilling the slightest drop ......

Last edited by Gretchenfrage; 2nd Feb 2013 at 12:25.
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Old 2nd Feb 2013, 12:57
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If you cannot fly any procedure/manoever without the aid of a flight director then you are not capable of piloting that aircraft, its as simple as that. The FD is there to reduce workload, not eliminate it as a lot of pilots tend to use it today. (And then they complain about being paid peanuts....well, thats what a monkey is worth)
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Old 2nd Feb 2013, 21:59
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Centaurus. Agreed. I tried to say as much somewhere on a AF447 string. Youve said it far better.
Gretchenfrage, flying " thru" the FD's on in a bus could/will confuse the autothrust. Its better to turn em off
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Old 3rd Feb 2013, 09:43
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Great stuff John, very well stated.
You can't imagine what some of the newer brigade do (or can't do), especially P2F pilots.
Regards.
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Old 3rd Feb 2013, 11:02
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Flight Directors are nothing more than a guide to get you going in the correct direction. My students are tought this with the addition of looking beyond the FDs at times as they may provide inaccurate cues at times.
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Old 3rd Feb 2013, 11:28
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I remember many moons ago us sitting in the lecture room of the Dash-8 ground school all wondering what the hell a "flight director" was ! We thought it must be a person in Ops or ATC !!
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Old 3rd Feb 2013, 11:54
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Well said !

Thank you Centaurus for this perfectly made point of no-nonsense aviation.

May you be heard loud and clear by those who need to hear you.

Svarin
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Old 3rd Feb 2013, 17:36
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Originally Posted by captjns
Flight Directors are nothing more than a guide to get you going in the correct direction. My students are tought this with the addition of looking beyond the FDs at times as they may provide inaccurate cues at times.
Agree, with one exception and that is the FDs on the Airbus 320/330/340/380 series, (I haven't flown the 777 or the A310/300 etc so can't comment).

The FDs on the Airbus tell you what the autoflight system is commanding...what it wants to do with the inputs it is being provided with if it had control of the airplane.

So in a way, that fact drives the FDs usefulness to two extremes, from 'very useful' on one end to dangerous on the other.

If one knows one's aircraft well and has been taught well, one would understand that the Airbus FDs can make one aware of what the autoflight would do with the airplane if you weren't hand-flying. (ed. Thus, the FDs will always be "centered", because the airplane is doing what the autoflight is commanding. QED) You can then make the decision to (re-)engage the AP or ignore (look through) what the FDs are conveying, as you wish.

The other extreme, the dangerous one occurs if doesn't know one's aircraft, in particular the A320/A330 series, and so treats these particular FDs like all previous airplanes, following their commands without understanding, as if the automation "knew" what it was doing in all circumstances. GIGO.

Like any computer, it has no "reason" for doing something - it doesn't "know" why it is doing something because the design is "hard-wired", but we are not.

What has been stated on this thread is completely true in my experience and my opinion - Centaurus' post is worth reading well. I think it is important to know when to look through the FDs and when the FDs are saying something important. Airbus recognizes this by stating that if you don't intend to follow the FDs, turn them both off.

PJ2

Last edited by PJ2; 3rd Feb 2013 at 19:43. Reason: add 'ed.' comment
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Old 3rd Feb 2013, 18:39
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Flight Directors etc

The foregoing (brilliant) discussion sort of fires white noise at the hoary continous problem of pilot training in the modern era of highly complex automated aircraft.

It seems to me that pilot training from ab initio to type ratings might well be as follows:

1. Pilots must be taught to operate transport aircraft up to their intended weight without any automation, and to include upset manouvres. This would then carry an "initial" rating, certifying competence to fly aircraft of that weight limit (for example).

2. To then be type rated on any modern transport aircraft (ex. Airbus) and in addition to the normal conversion, the candidates should undergo an intensive flight control systems course ending with an appropriate examination. This course would entail a full understanding of the design philosophy, sensor layout, operational modes and failure cases.
In my opinion if you don't thoroughly understand what a modern FBW multi redundant channel flight control system is all about you shouldn't be operating the aeroplane.

Combing solid, initial light aircraft plus heavy manual flight operational training with 2. above should give me a pilot I can trust.

(ex just flight test bloke, now in the back with his fingers crossed)
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Old 3rd Feb 2013, 18:51
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Flight Directors etc

One further point here;
I think a big problem lies in the (apparent) Airbus philosophy which seems to advertise it's aeroplanes as ultra safe and if the automation is used throughout, the aeroplane "will fly itself" and you are protected throughout the flight regime.
If the avionics were guaranteed 100% safe then I guess we wouldn't have a problem, and you wouldn't need to know anything other than which button to push. However, they are not 100% safe, that is an engineering fact, and it is therefore necessary to thoroughly understand what it is you are operating, what the limitations are, and how to handle failures.
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Old 3rd Feb 2013, 18:57
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FDs or Command Bars

Very good points made.

When I made the switch from military to commercial aviation, I was doing sim training and the sim instructor kept telling me to "follow the command bars". I responded "those are SUGGESTION bars, I'll do the commanding thank you"

As someone mentioned above, learn to look through the FD bars at what you are expecting to see. Pitch and power will save your butt.

Good discussion.
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Old 3rd Feb 2013, 19:16
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I am still stuck on the part where a 250 hour pilot has a 737 type.

Let's start there. That after everyone has fired the kids, then we can require all pilots to sit in an ATC 610 and hand fly a couple approaches to keep their jobs.
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Old 3rd Feb 2013, 20:18
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The other extreme, the dangerous one occurs if doesn't know one's aircraft, in particular the A320/A330 series

Surely, one only flies the ball to keep in control of the situation .. ie one might take an interest in the FD, but only in the same way that one takes an interest in any other bit of information eg OBS deviation, ADF/RMI needle, etc. ? ( I guess the new folk haven't seen those terms .. ?)

I never considered myself skilful enough to follow the bars blindly .. unless I flew the ball, and the bars eventually caught up with my hapless flying, I ended up well behind the game play ..

He who flies the bars, without thinking about what he (or she), is doing .. is a fright waiting to happen somewhere along the way.
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Old 3rd Feb 2013, 21:19
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( I guess the new folk haven't seen those terms .. ?)

...maybe it's still taught but just in case...



He who flies the bars, without thinking about what he (or she), is doing .. is a fright waiting to happen somewhere along the way.

I once asked why my F/O was low on the visual approach - response was, that's what the FDs were saying to do... We had a chat.

PJ2
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Old 4th Feb 2013, 00:40
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response was, that's what the FDs were saying to do... We had a chat

(a) oh, dear.

(b) mastery of understatement is demonstrated admirably ..

A great pity Centaurus was not able to come along to lunch the other week .. 'twould have been an interesting conversation, I'm sure.
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Old 4th Feb 2013, 01:52
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The Dash 8 MEL allows you to conduct a flight with the Autopilot and or Flight Director unserviceable.
During my endorsement in the simulator and throughout line training do you know how many times I conducted a raw data take-off? That's right – Zero.
The company has placed a small clause in the manuals to allow raw data approaches in strictly day VMC but this opportunity is rarely taken up. It's no surprise there is such an attitude as I witnessed a speech by a senior pilot lambasting a supposed cowboy operator for daring to practice the odd raw data take off. "How would you know what attitude to fly?" Unbelievable – especially as the take off mode of the dash 8 300 flight director only ever commands a fixed 9 degrees which we are always required to "Look Though" to achieve the actual attitude required for a normal two engine initial climb.
It's likely the first time a pilot will have to conduct a take off with no flight director will probably be as a result of applying the MEL to return an aircraft full of people to a maintenance base from some remote black hole airport in poor weather.
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Old 4th Feb 2013, 03:46
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The MEL is a permission to operate with a bit of kit U/S, not a command to do so.

I would expect, in your airline's case, that the line captain would decline such an MEL operation .. as the preamble to your MEL will, undoubtedly, permit and commend.

We all have been caught out with youthful exuberance and gung-ho overconfidence. The very great majority of us who have made it to greybeard and expanding tummy status ... didn't get killed at the time doing so and, so, had an opportunity to learn from our youthful stupidity.
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Old 4th Feb 2013, 06:37
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Very good points made.

When I made the switch from military to commercial aviation, I was doing sim training and the sim instructor kept telling me to "follow the command bars". I responded "those are SUGGESTION bars, I'll do the commanding thank you"

As someone mentioned above, learn to look through the FD bars at what you are expecting to see. Pitch and power will save your butt.

Good discussion.
Wow. Here is a SUGGESTION. Listen to your instructor!

Whilst I agree with the general concepts that we should be aware of the pitch and power, and be able to fly without FDs, your attitude seems a bit off to me.

There are integrating terms in many control laws, so if you don't want to follow th FD just turn it off. If you leave it on and don't follow it, it will increasingly given you bollocks anyway, because you'll confuse the **** out of its control laws. Not following it is a self fulfilling prophecy.

If it's on, follow it, unless you don't want it or it is clearly faulty, in which case turn it off. Simples.
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