"TCS" Functionality on Big Iron
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Join Date: Mar 2009
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"TCS" Functionality on Big Iron
Many private/business jet aircraft (Citations and Lears and at least some of the bigger Bombardiers that I know of, presumably others) have a TCS function as part of the autopilot -- one one-touch button that deactivates the autopilot while held to allow a brief bit of hand-flying and when released reactivates the autopilot synchronized to the new heading/attitude/etc.
Does this functionality exist in the commercial world? What about regionals (were I could imagine the ability for some quick hand flying would be more valuable)?
Cheers,
--Nick
Does this functionality exist in the commercial world? What about regionals (were I could imagine the ability for some quick hand flying would be more valuable)?
Cheers,
--Nick
Join Date: Aug 2000
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AFAIK, this button is called "CWS" for "control wheel steering" on the big birds. At least it was labelled CWS on the 737 simulator on which I did my multi-crew training many years ago. It does not really deactivate the autopilot, but only decouples the autopilot servos while leaving the autopilot running in it's current mode. When the button is released, the autopilot will resume as if nothing had happened.
On "my" TCS-button equipped aeroplane, it also sets the autopilot to the current pitch/VS/speed/bank values when in pitch/VS/FLC/roll mode. I do not remember, if "CWS" does that also.
On "my" TCS-button equipped aeroplane, it also sets the autopilot to the current pitch/VS/speed/bank values when in pitch/VS/FLC/roll mode. I do not remember, if "CWS" does that also.
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Doesn't exist in the 737s i know, but of course we can just overpress the autopilot and it switches to CWS and holds attitude and bank after being released (bank less than 6° gets corrected to wings level). Even possible to just overpress one channel (pitch or bank) and let the other continue on automatics, if you want to switch back from CWS to any other mode you have to activate that mode actively, won't do that on its own. Autothrust can be overpowered by manual input at any time, but it supposedly wears down the clutch if you do it too often.
I fly Dash 8 200 and 300s and we use it on every take-off while accelerating and getting the flaps up (Company SOP.) It doesn't have to be used in conjunction with the autopilot, we use it to adjust the flight director command bars when hand flying. So we take-off with flight director HDG and GA (Go Around, provides a 12 or 9 deg pitch up command depending on type). We rotate to the pitch bar and get the gear up, once we've accelerated to V2+10 to 20 we get the PM to set IAS which has the pitch bar commanding the IAS at the time the button was pushed. Climbing through 400' we select flap 0 and hold the TCS button while lowering the nose slightly to accelerate to the desired climb speed. The pitch bar will stick to the actual aircraft pitch until the TCS button is released at which time it commands the IAS achieved at the time the button was released. The autopilot can only be engaged after climbing through 1000' (aircraft limitation) at which time any IAS changes are made using the pitch wheel on the flight guidance controller.
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Every takeoff on a Falcon2000EASy.
Used to sync the flight director with the desired flight path since the path entered into the AFCS/GD is for single engine out guidance, once above TOSA use it to sync the Flight Director for desired rate of climb or speed.
Use it frequently and love it...
Used to sync the flight director with the desired flight path since the path entered into the AFCS/GD is for single engine out guidance, once above TOSA use it to sync the Flight Director for desired rate of climb or speed.
Use it frequently and love it...
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How often do you actually use this feature in daily operation and is it actually authorized by your operator?
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The last airplane I flew that had something similar was a DA40, it was confusingly called CWS there. Now on my 737 CWS is basically the 'Airbus mode', set a pitch or bank (>6°) and the airplane will maintain it after you let go of the controls. You can also use it mixed with other A/P modes, you could have LNAV as a roll mode while still controlling pitch manually through CWS or MCP speed as pitch mode and fly the airplane manually in a lateral sense...
B767 has control wheel steering. I never used it. Just either use the autopilot or turn it off and hand fly. B777 does not have it, but it is FBW and has so many computers working that under normal conditions you are never completely hand flying.
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Every day/flight in the C680 during take off. Best way of setting up the flight director during initial climb, ie pitch or FLC (IAS), when manually flown before engaging a/p (in our case 400' AGL minimum in the climb).
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Not any more, that's the old limitation. It went away together with the "a/p disengage in the event of engine failure during final approach"-memory item among other things.
It's still 1000' AGL at cruise.
The descend limit is (still) is 80'.
It's still 1000' AGL at cruise.
The descend limit is (still) is 80'.
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On a side note, I still normally engage at 1000' unless otherwise called for. The 600' difference between the new and old limitation is only a few seconds anyway.
