3
$\begingroup$

I have heard about auto-thrust yet I still don't know what it is. Can someone please explain to me what it is?

I know that I can just Google this up, but I was hoping that a community which revolves around aviation would be able to answer my question.

I did end up using Google to do some preliminary research and I found this definition:

An autothrottle (automatic throttle) allows a pilot to control the power setting of an aircraft's engines by specifying a desired flight characteristic, rather than manually controlling the fuel flow.

| improve this question | |
$\endgroup$
5
$\begingroup$

In its basic form, it is just like the cruise control in a car.*

Here is a photo of the autopilot control panel on a Boeing 777. Note the "IAS 200" window on the left:

enter image description here

IAS stands for "indicated airspeed". When engaged, this setting tells the auto-thrust to adjust engine power to maintain 200 knots of airspeed.

Just like a car, when you go uphill you need more gas to maintain a constant speed, and when you go downhill you give it less gas. If the downhill is steep enough, you may have to use some brakes to maintain a constant speed.

Same thing happens when a plane pitches up to climb or pitches down to descend. Airspeed, vertical speed and engine power are closely related - changing any one will impact the remaining two. This is the fundamental of how planes fly, and likely your first ground school lesson if you learn to become a pilot. Auto-thrust is a component of the autopilot system which manages engine power. Note that I used constant airspeed as an example in the previous paragraph: advanced autopilots have many modes, and it can be set to maintain constant vertical speed instead of airspeed. But in all cases, auto-thrust manages engine power.

* Well said TomMcW

| improve this answer | |
$\endgroup$
  • $\begingroup$ It is worth noting that many aircraft are not equipped with auto-thrust or auto-throttles, including many of those with sophisticated autopilots. $\endgroup$ – J Walters Feb 7 '17 at 22:15
  • $\begingroup$ @JonathanWalters I wouldn't call those autopilots "sophisticated" then. And I'd say it's pretty common. Surely it is rare in GA, but on the passenger side, I'd bet at least 8 out of 10 flights you can book at major airlines is flown on an aircraft with auto-thrust. $\endgroup$ – kevin Feb 7 '17 at 22:24
  • 1
    $\begingroup$ I was thinking specifically of the Garmin GFC 700 as an example. I suppose there could be good reason to not call it sophisticated, but I would and others in the industry do. $\endgroup$ – J Walters Feb 7 '17 at 22:47
  • 1
    $\begingroup$ @JonathanWalters the autopilot (and FMC) on Airbus and Boeing can do de-rated takeoffs, fuel economy management, descend energy management, auto-trim etc. I'd say these are the things that are missing, but then I agree many autopilots are very capable even without auto-throttle. $\endgroup$ – kevin Feb 7 '17 at 23:06

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.