Autothrottle curiosity

[bjratchf 80]

That's certainly interesting, given how aircraft actually operate. What experience do you have to be making these statements?

 

The 737 has an AT mode called "RETARD." It specifically retards the thrust to idle. An Airbus uses a different methodology, though, where the pilot must physically move the thrust lever out of the detent.

 

The 717 too! Within 50ft, it'll go to idle. Also, the 767. 

[cbrdriver 0]

Thats a sim thing, the real airplane won't do that.

I do understand that, Joe, and thank you. I was offering an example of what would happen in the NGX if AT was left active.

His question seemed to me to be a comparative question; the real Turkish Airlines as compared to the NGX.

" Now my question is if the 737 NGX can land with ap off and AT on. "

[bTripleSeven 3]

Indeed the question is quite confusing: Did I ever saw a 777 landing with autopilot OFF and autothrust ON? Never. A bus? Neither. 

Let s recap how autothrust works on landing: Usually during the approach it is a speed mode that is selected, so ship maintain airspeed and autothrust adjust to that. When close to the ground, based on radio altimeters the autothrust will automatically retard the throttles to idle. Most of the time the mode is annunciated (vocal in airbus), on the PFD on Boeing.  Of course there are always special cases but that`s for general operation. 

For low vis operation the 3 radio altimeters needs to be functional. Either the aircraft is smart enough to compare the 3 radio altimeters values and "downgrade" the system in case of one radio altimeter failure or in older planes the comparison was done by the pilots when one was calling out `five hundred`for example.  What I love in Boeing is that the throttles are moving. So if by any chances the throttles should go to idle I would have an immediate feedback that something is wrong. Again, special cases apply = You are coming way too high on the ILS = your throttles are going to be hard idle anyway = you should not even consider continuing your approach if you are too low (see the 777 LAX accident).

 

Last but not least, in your question you are mixing autoland and autothrust; Autoland flies the ship, autothrust maintain the speed. The 2 features are independent :you can engage autothrust without approach mode or you can engage approach mode without autothrust. Is that recommended? Absolutely not. Is that allowed? Depends on aircraft manufacturer and airline policy.

[bTripleSeven 3]

fstul : " NOW, if at that point AT would have spooled down the engines the GA can be a disaster."

Answer: YES it could be a disaster if you did not made your homework and look at your performance for a go around with one engine out. Since during planing phase and descend phase we look at those operational aspect IT IS NOT going to be a disaster if we go around after touching down.

[BlueStar 323]

That's certainly interesting, given how aircraft actually operate. What experience do you have to be making these statements?

 

The 737 has an AT mode called "RETARD." It specifically retards the thrust to idle. An Airbus uses a different methodology, though, where the pilot must physically move the thrust lever out of the detent.

Kyle,

 

One of my coffee drink'n buddies has been on the B738 for about ten years. He uses the auto-throttle in all phases of flight including landings. All landings are manual using the HUD (no auto-land) and auto-throttle. What gets him excited is talking about his time on the MD-11. :-))

 

blaustern