From TOGA Mode to normal A/T mode and back

[737Andi 6]

Hi, 

i was just wondering how this is done on the A320 and the 738.

On the A320 you have detent zones for toga and climb detent.

On the 738 however these detents are not present. You can engage toga with the toga button on the throttle lever. But how do you set normal A/T mode after toga engagement when you dont need toga anymore? Do you just need to flip the A/T lever on the MCP twice or how is this done normally? 

Thanks!

Best regards Andi

[threexgreen 3,133]

If not using VNAV for takeoff, at acceleration height you select flaps up speed on the MCP and the F/D will command the reduced pitch needed to accelerate. MCP SPD is now active on the FMA and climb thrust selected. Normally you would select VNAV at acceleration height which will do this on its own. You can also arm VNAV before takeoff and you just have to follow the F/D.

[737Andi 6]

Thanks for your answer. It helped me to understand the situation better.

How would I proceed in both airplanes when I apply full manual thrust on the throttle during flight and want to get back to controlled A/T mode afterwards. I suppose you have to switch on the deactivated A/T and then decide between VNAV or direct Speed Mode.

Is that correct?

Edited June 8, 2019 by 737Andi

[downscc 1,327]

I can only answer to the Boeing, switching from A/T to manual is done by disconnecting A/T.  Use the PMDG Options Keycommand menu to map that action to a key command.  To switch from manual to A/T you simply turn the A/T switch back on.  However, about the only time I turn off A/T is during the approach.  During flight I prefer to use the SPD INTV feature which gives you manual control over speed while in a VNAV mode.

[skelsey 765]

In the A320 generally if all you have done is push the thrust levers forward from CL with the autothrust active, pushing them forward will change to manual thrust and re-arm the A/THR (A/THE blue displayed). As such pulling the thrust levers back in to the CL detent from TOGA or MCT will re-engage the autothrust.

As always verify on the FMA (A/THR white in column 5/expected thrust mode active in column 1).

[threexgreen 3,133]

15 minutes ago, skelsey said:

In the A320 generally if all you have done is push the thrust levers forward from CL with the autothrust active, pushing them forward will change to manual thrust and re-arm the A/THR (A/THE blue displayed). As such pulling the thrust levers back in to the CL detent from TOGA or MCT will re-engage the autothrust.

As always verify on the FMA (A/THR white in column 5/expected thrust mode active in column 1).

Out of interest, I've always wondered how you manually control thrust on an aircraft that has detent positions for the thrust levers. What if you increase thrust manually and move the levers close or right into one of the detent positions? Will that only have an effect when autothrottle/-thrust is armed?

[skelsey 765]

6 minutes ago, threegreen said:

Out of interest, I've always wondered how you manually control thrust on an aircraft that has detent positions for the thrust levers. What if you increase thrust manually and move the levers close or right into one of the detent positions? Will that only have an effect when autothrottle/-thrust is armed?

On the A320, there are four detents: IDLE, CLIMB, FLEX/MCT and TOGA (full forward).

The range between IDLE and CLIMB is a manual thrust range which works exactly as you would expect... manual control of thrust proportional to the thrust lever position between idle and rated climb thrust (calculated by the FADEC).

In normal operations, when you take off, you place the thrust levers in to the FLX (reduced thrust) or TOGA (full takeoff thrust) detent. These are both manual thrust detents, but this will arm the autothrust.

When you bring the thrust levers back to the CL detent, the autothrust will become active and the autothrust will control the thrust between the idle and climb rating limit (i.e. the levers act as an upper limit to A/THR authority).

If you move the thrust levers back from the CL detent, the A/THR stays engaged but again the levers act as a limit, so the A/THR will never command thrust higher than the lever position (and the aircraft will warn you about this as there's no real reason to deliberately do this). When the thrust levers reach the IDLE detent the autothrust automatically disconnects.

Likewise if you push the levers forward from CL you will go back in to the manual thrust range and the thrust will again be commanded to the thrust lever position. It's all very intuitive actually when you get your head round it... want to go around? Shove the levers forward and everything else clicks in to place.

In single-engine operation the A/THR range is automatically extended to the MCT (Max Continuous Thrust) detent as obviously this is the appropriate rating to use in single-engine operation.