Auto Throttle Help

[iFlySimX 148]

Hi,

Might be a stupid question but when I takeoff and engage the Autopilot and the Auto Throttle I can still adjust the Throttles.....Is that normal?

Thanks!

[KyleD 1027]

Hi,

If you do not have your throttles in the CLB detent then yes, you will still be able to control your thrust. You should have them in the CLB detent for the ATHR to work.

[iFlySimX 148]

Hi,

If you do not have your throttles in the CLB detent then yes, you will still be able to control your thrust. You should have them in the CLB detent for the ATHR to work.

What do you mean in the Climb Detent? Thanks!

[KyleD 1027]

Well, I first will refer you to the Step by Steps and the other manuals, but for a basic practical explanation-

The throttle is set up to have several detents, along with a range of manual travel. The basic ones are the idle detent at the lower end, and at the top Climb (CLB), Max Continuous (MCT), and Max Takeoff/Go around (TOGA) detents. As you move the throttles forward from idle all the way up to the top, you will hear three 'clicks'. The first click is the CLB detent, the second is the MCT detent, and the third and final click is the TOGA detent. See this diagram for a side and top view of what I refer to:

Now, they all have a slightly different purpose.

- CLB- in this detent ATHR is used by the FMGS. Basically, anything in-flight being controlled by the ATHR requires the throttles to be in this detent. You can think of it as you giving the ATHR full control of thrust, allowing it to go to it's highest limit in CLB mode, or to idle, without you having to do a thing.

- MCT- this will give you maximum continuous thrust. You can think of this as giving you the maximum amount of power that you can sustain over a longer period of time.

-TOGA- gives you the maximum power the engine can produce under the atmospheric conditions it is in. So, on takeoff this can be desirable on a short field, and also on go-around you want everything the engine has. But, you don't want to stay at that amount of power forever as you risk putting more wear and tear on the engine than you should.

Probably went into a little too much more detail than you were bargaining for, but that is just a simple look in to what they mean and do. When you want to use the ATHR and want the autopilot to have full control over the thrust, place your throttles into that CLB detent. The easiest ways to know are to reference you E/WD, or the FMA on the PFD, and lastly to simply listen for the 'clicks'. If you used TOGA for takeoff, back the throttle 2 clicks back, and you'll be in the CLB detent. If you used FLX (which is the MCT detent), back the throttles 1 click. If you are in the manual thrust range, advance the throttles to the 1st click and that is the CLB detent.

For what you described above, you took off, so that tells me that you were in one of the detents to start with, which should automatically engage the ATHR. All you would need to do is move the throttle back 1 or 2 clicks (depending on what you used to takeoff) to be in the CLB detent and allow the ATHR to do its work. Now, if you turned off your ATHR and moved the throttle lever out of the detents and reengaged the ATHR again, then you would still be able to control thrust, until you place the throttle back into the CLB detent.

Hope this helps.