I'm getting into the autothrust world and I have the question of whether it would be possible to disengage it and select the thrust manually in a plane that already has autothrust. How could it be done? Maybe it differs from plane to plane.

  • $\begingroup$ ....disengage the autothrottle and make thrust inputs using the throttles? $\endgroup$ – Carlo Felicione Aug 8 '18 at 1:28

You are correct that different planes operate slightly differently, but they are mostly pretty similar. Just as with the autopilot, the autothrust can be disconnected and the airplane can be controlled manually.

Below is an image of the Mode Control Panel on the 737 NG, which is located just below the windshield. The section that controls autothrust is located towards the left side. To disconnect the autothrust, you can just flip the "arm" switch to off.

737 NG MCP

Below is an image of a 737 NG cockpit, with the thrust levers located in the middle. With autothrust on, the levers are moved by the autoflight system to correspond to the autothrust setting. The levers can be moved by the pilots but the system will try to drive them back to the commanded position. Once autothrust is turned off, the system no longer moves the levers and they can be controlled by the pilot manually.

737 NG Cockpit

Airbus planes such as the A320 are a bit different. The levers do not move to match the autothrust setting, but autothrust can still be turned off to use the levers manually. The levers can also be pushed forward past the "climb" detent, which overrides autothrust to choose higher thrust settings.

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    $\begingroup$ "The levers do not move to match the autothrust setting, but they also have specific detents that can be used to override autothrust to set certain manual thrust settings." Detents are used to set autothrust limits, not override it. Also in an Airbus, the A/T can be disconnected, and the levers work just as in any other aircraft. $\endgroup$ – Sami Aug 7 '18 at 18:07
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    $\begingroup$ @Sami from the linked post, "When the thrust levers are beyond the CLB detent, thrust is controlled manually to the thrust lever Angle." I edited the wording here a bit. $\endgroup$ – fooot Aug 7 '18 at 19:19
  • $\begingroup$ Well, goes to semantics a bit, but beyond CLB autothrust is not usable, so it's off. Anyways, it's agains airbus' SOP to use the thrust levers to override autothrust though it is possible. $\endgroup$ – Sami Aug 7 '18 at 19:38
  • $\begingroup$ On the 737, even with the autothrottles engaged, you can override the servos and move the thrust levers. The servos will pull (or push) against you to attempt to put the throttles where they "should" be, but it isn't difficult to override them. This action does NOT disengage the A/T, although if you get tired of overriding the servos, that may become the obvious choice. $\endgroup$ – Ralph J Aug 7 '18 at 19:46

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