What Value is a Flight Director

Discussion in 'Pilot Training' started by kontiki, Feb 18, 2020.

  1. kontiki

    kontiki Cleared for Takeoff

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    I've been reading up on Flight Director operation for 767s, actually for a specific work related MEL question, but it occurs to me, I really don't get what value they provide in general.

    I've worked on and around airplanes that had them for years.

    I've flown a couple G1000 aircraft, (172 & DA40) that had a flight directors, I could turn it on or off. I didn't really get what it did for me.

    Reading through the FAAs advanced avionics handbook, it's seems to insinuate they are possibly confusing.

    When are they valuable? What exactly do they do for you?

    Thanks,
     
    Last edited: Feb 18, 2020
  2. James331

    James331 Ejection Handle Pulled

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    They turn you into a meat servo
     
  3. PaulS

    PaulS Final Approach

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    FDs are great, if you have one use it. BUT you need to understand how to use it and what it is doing at all times or it can eat your lunch. I use it up until I enter the pattern, then shut it off. Makes flying precisely much easier.
     
  4. Tantalum

    Tantalum Final Approach

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    ^yeah, if you have everything set up right, especially if you are in IMC, it's a great resource for handflying.. you're basically a "human autopilot"

    Granted, you have to set it up right

    If I'm just tooling around I leave it off. I find it most valuable on departure into IMC, the TOGA and subsequent IAS 120 climb and departure course really reduce the workload in that initial phase of flight
     
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  5. write-stuff

    write-stuff En-Route

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    Pretty nice accessory when going missed!
     
  6. PaulS

    PaulS Final Approach

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    Especially if it's coupled to an autopilot.
     
  7. PaulS

    PaulS Final Approach

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    I've been using the toga less for normal departures, maybe just the cold weather here and I've been flying light, but follow the FD in TO mode and I end up at 135 knots before I know it.
     
  8. Ryan F.

    Ryan F. Line Up and Wait

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    They're very important for jets. Not so important for piston airplanes. Nice to have for high performance piston airplanes though.

    Generally speaking, flying a jet without a flight director is very challenging. While holding altitude, a "pixel" or two up or down can result in an immediate and significant rate of climb or descent. Rolling out from a turn a little late or a little early can result in a minor-to-moderate-to-major heading deviation, depending on pilot input. Simply stated, a flight director makes managing the aircraft much, much easier and is basically required for normal operation. An inop flight director would be a go-no item for my operation and most others. It would also "inop" the autopilot in most aircraft.

    There are certain profiles which may not "require" the use of one. For example I did landing currency today at FSI in the G450 sim. One of the landings was a visual pattern. I hand flew the aircraft during the climb and asked my SIC to set altitudes, FGP modes (HDG, FLC, speeds) and headings for the climb, crosswind and downwind turns. I also utilized the autothrottles. On downwind the SIC built a 3 mile visual in the FMS with a 1500' altitude constraint at the 3nm fix. I kicked off the autopilot and the autothrottles before turning base and then armed LNAV and VNAV, and asked him to roll the altitude preselect down to field elevation. This allowed me to take advantage of the flight director for both lateral and vertical nav, even though I wasn't using any of the automation.

    Normally I'd use the HUD for all of this, which uses different symbology for the flight director, but works the same. But this was an older HUD I in the sim instead of a HUD II which I have in my work airplanes. HUD I = no thrust director. Therefore I used the PFD's single cue FD symbology and the thrust director -- another great tool in jets which feature it, as it helps the pilot make power adjustments for target airspeeds. As I was rolling onto final I figured "what the hell, let's go raw data," kicked off all the lateral and vertical modes and just used pitch and power to get me on the ground. Works okay, but it's a lot of work, a lot of jockeying the power levers up and down, some pitch changes. Wasn't a big deal, but just not ideal for everyday ops. A good sim exercise.

    Allow me to reminisce. I know I'm entering TLDR; territory.

    One of the more challenging situations I've had to overcome in my career was many moons ago, at least 12 years if I'm not mistaken... ? An old Hawker 400A, not the Beechjet, but rather the legitimately named Hawker 400A and the one I was flying was made in 1969. This airplane had a lot of issues. Don't ask me to explain it, but it was a real thing: if the SIC placed an altitude constraint in the right side box (GNS-XLS if my memory serves) and the PIC then executed a direct-to or any other waypoint change from the left box, it killed the one-and-only Flight Director which was of course reserved for the captain. FD in that airplane was a mechanical contraption, floating over a mechanical ADI. By killed, I mean the FD would repetitively do this: slowly pitch all the way up while increasing bank to the left. Then it would snap back to straight and level, slowly pitch up/turn left until it reached its limits, etc., ad nauseum. This also kicked off the autopilot. It would do this until shutdown.

    I was flying with a brand new SIC. Great guy, knew what he was doing, but forgot the "this is a weird, old airplane" brief. (Real brief, by the way.) We were assigned a STAR. The STAR contained one altitude constraint. He placed the one altitude constraint into the box. He didn't mention it, and I missed it. We were given "direct XYZ." I made the D-> command on the left side while on autopilot and boom, the autopilot kicked off and I was suddenly hand-flying while watching this mechanical flight director do its dance. I knew the FD was done.

    It is a given that in these situations the weather is always bad. This is to be expected. It's some kind of rule: all (okay, most... ) mx issues will come to bear when you're tired, it's late at night, and the weather's bad. Fair enough on all counts. Sure enough the airport in question was reporting weather at ILS minimums and I was going to have to hand fly this approach with little to no assistance from the automation. Which I did... not saying it was the greatest approach ever but it was gratifying to see the ALS as I was hearing my SIC call "minimums."

    Pistons: I've flown piston airplanes with flight directors. They're becoming more common. They work exactly the same, but piston airplanes aren't very difficult to manage from an attitude and power perspective. It's a nice tool, but by no means a game changer for those aircraft.
     
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  9. Checkout_my_Six

    Checkout_my_Six Touchdown! Greaser!

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    yup....TL;DR. lol :D
     
  10. BrianNC

    BrianNC En-Route

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    As someone who has never flown a FD, and really don't know about them, don't most pilots just use the autopilot? I don't think I've ever seen anyone use a FD in a video. It's always the autopilot.
     
  11. PaulS

    PaulS Final Approach

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    I read it, good stuff.
     
  12. PaulS

    PaulS Final Approach

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    I use it all the time, Cirrus sr-22 g6. It's like a heading bug and altitude bug on steroids. It also drives the autopilot, but is still useful when the autopilot is off. I think everyone would benefit from one, especially IFR. Like I said before, there are situations where it becomes a distraction, in those cases I can just turn it off.
     
  13. Tantalum

    Tantalum Final Approach

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    That is honestly the best way to describe it
     
  14. Checkout_my_Six

    Checkout_my_Six Touchdown! Greaser!

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    yup....most of it was good. ;)
     
  15. BrianNC

    BrianNC En-Route

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    Understood. But why not just use the autopilot? Just to hand-fly for hand-flying proficiency even though it's giving you the inputs to make?
     
  16. Tarheelpilot

    Tarheelpilot En-Route

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    The way I manage understanding the FD is that it’s giving the pilot the same guidance programmed for the autopilot. So if you are managing the automation as if the ap is on then follow the fd it works out that you fly the same way the ap would. So any changes to the automation mode should be verbally directed by the PF and you’ll look like a rock star. Behind all the magic pilots should be learning the basic pitch + power combinations and the resultant performance. That way when all the automation and PFM dies you can still safely operate the airplane
     
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  17. Briar Rabbit

    Briar Rabbit Pre-takeoff checklist

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    When taking off into IFR with the Garmin GFC 500 you are not allowed to turn the autopilot on until 800 feet AGL. Dark nights and when there is minimum visibility due to clouds it is comforting to know your are doing a good job keeping the pitch where it needs to be. Also if the autopilot fails the Flight director may still be giving you guidance.
     
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  18. kgruber

    kgruber En-Route

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    Allows you to hand fly FAC while half asleep.
     
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  19. kontiki

    kontiki Cleared for Takeoff

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    Thanks very much for all the effort that went into the responses. The original question on my end was from our Maintenance Operations folks about the (O) operational procedures in a 767-300 MEL for deferral of a failed ADIRU IRU function. The procedure requires the crew to select the alternate source input for the failed unit and engage the A/P after in flight. This aircraft is not certified for A/P takeoff, but has "full time" FD. I found the answer in Boeing's Master MEL/Dispatch Deviation Guide, and once I knew what I was looking for it's has two sentences in the AMM Autopilot D&O Section that confirm it. It was a slow day, I decided to see what I could learn.
     
  20. Arnold

    Arnold Line Up and Wait

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    When I flew the Shorts 360 we had FD but no autopilot. It improves precision and after hand flying for eight hours, and with people changing the CG every time they go to the can, it was my pleasure to simply be a "meat autopilot."
     
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  21. ktup-flyer

    ktup-flyer En-Route

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    I like them a lot. As others have said, it makes it a lot easier to be precise.
     
  22. Tarheelpilot

    Tarheelpilot En-Route

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    I doubt the original post had an hope of getting an answer to your question.

    glad you read the MEL. ;-)
     
  23. Ryan F.

    Ryan F. Line Up and Wait

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    Agree -- this is a GA pilot forum. You'd probably do better with questions like that at PPW.
     
  24. Checkout_my_Six

    Checkout_my_Six Touchdown! Greaser!

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    yup....no one here knows how a Flight Director works. ;)
     
  25. kontiki

    kontiki Cleared for Takeoff

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    To be sure folks here told me exactly what I was looking for, and I appreciate it. I'm an Avionics Engineer in a field support group and low time private pilot.

    To be honest, I didn't expect to see responses from pilots with so much background. Which is why I didn't mention what led me to ask the question in the very beginning. I don't mind sharing info on stuff when others might find it interesting though.
     
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  26. Warmi

    Warmi Pre-takeoff checklist

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    Even a simple TruTrak has a basic flight director - I never really used it either outside of it being used by the AP but I don’t do IFR either.
    On the screen you get these magenta “wings” which you are supposed to follow with the yellow triangle and sort of hand fly on rails :)

    FF53A47E-F113-4DC9-A004-43F25A791189.jpeg
     
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  27. PaulS

    PaulS Final Approach

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    I do all three, that is, FD off, FD on and Autopilot. There are situation where the FD is a distraction, the pattern is one. I still occasionally screw up the settings for the FD so it commands something I don't want. In that case it's hand fly with it off until I get it figured out. Most primary training is done with the FD off from what I've seen. My IFR check ride was almost all flown by hand, except for the last approach which was coupled. You have to demonstrate you know how to use the automation if it's available.
     
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  28. PaulS

    PaulS Final Approach

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    The FD has no effect on basic pitch and power combinations, at least the ones I fly. You can still blast into a procedure 50 knots too fast or get way to slow with a flight director if you don't know that stuff.
     
  29. Tarheelpilot

    Tarheelpilot En-Route

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    I didn’t say it had any affect but thank you for pointing that out.
     
    Last edited: Feb 19, 2020
  30. PaulS

    PaulS Final Approach

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    You're welcome.
     
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  31. kgruber

    kgruber En-Route

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    Rules of Flight Director

    1. If it is "ON"................follow it
    2. Otherwise, turn it "OFF."

    NEVER let it wallow around with the pilot not following its commands.
     
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  32. PaulS

    PaulS Final Approach

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    Amen. It's amazing how your eye gets sucked right to it if it's not off when it should be.
     
  33. Briar Rabbit

    Briar Rabbit Pre-takeoff checklist

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    When we installed our G5's it was recommended to set the flight director up with a single cue format for the G5 AI. I am still wondering if it would be easier to fly ILS approaches by hand with the flight director in the Dual Cue format instead of watching the tape on the side of the G5 or the single wings? Some nice flying day I am going to experiment, seems like that would more closely resemble the original CDI that was removed.

    upload_2020-2-19_14-42-57.png
     
  34. PaulS

    PaulS Final Approach

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    Single cue is more intuitive in my opinion. In the perspective+ (G1000) you have glide slope indicator next to the FD and CDI right below.
     
  35. Arnold

    Arnold Line Up and Wait

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    I've used both, you get used to what you have. If you can experiment sounds like a good idea. I actually prefer dual cue.
     
  36. Ryan F.

    Ryan F. Line Up and Wait

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    It's a matter of personal preference. I fly with some former military who tend to prefer the dual cue but I've never cared for the presentation.

    Becoming accustomed to the dual cue is a lot like (in my opinion) getting used to HUD symbology. Keep in mind the flight director isn't supposed to mimic the CDI, it is designed to put the aircraft in the right pitch and bank necessary to intercept and maintain lateral and vertical tracks. You'd be following the single or dual cue presentation "towards" the localizer/glideslope on an ILS.

    No reason not to experiment with it. Try both. Just keep in mind the FD is good to use for most/all phases of flight, not just an instrument approach.
     
  37. Greg Bockelman

    Greg Bockelman Administrator Management Council Member

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    FYI. With single que, if you lose either roll or pitch info, you lose the whole thing. With dual que, if you lose one, you don’t lose the other. FWIW
     
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  38. kgruber

    kgruber En-Route

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    My first flight director was a Bendix M4D add-on. It had two green balls and you were to superimpose the two red balls over the green.
    [​IMG]
     
  39. PaulS

    PaulS Final Approach

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    Nice!
     
  40. noahfong

    noahfong Pre-Flight

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    As others have said, flight directors are great. But you have to know how to use it. It was a mystery to me until I flew for a regional (CRJ pilot). I'm finding out that most pilots don't know how to use a FD unless someone who has jet time showed them.

    A FD-equipped G1000 would have an autopilot that depends on a functioning and "sync'd" FD. You would have to get the FD working in order to use the autopilot.
     
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