When do you fly manually?

[Jeroen Hoppenbrouwers]

Would real pilots ever fly this sort of approach with A/P connected but with manual thrust control?

Interesting question. Which translates to:

Does the AP assume 'speed by elevator' or 'speed by thottle' in the later phases of the approach?


Hoppie

[Hardy Heinlin]

By the way, the Thessaloniki situation is not only turbulent, it's also an overweight landing (emergency) with 340 tons on a 2400 meters runway. Also, the details in the turbulence structure is randomized every time the scenario is loaded: So sometimes you may have more or less luck -- especially in the flare phase. Each time it's different.


|-|ardy

Does the AP assume 'speed by elevator' or 'speed by thottle' in the later phases of the approach?

AFDS-wise, G/S and V/S are always airspeed on throttle, vertical speed on elevator.

Basically, any climb and descent flight path angle is always set by both power and pitch, but when pilots talk about elevator or throttle priority, they just mean short term control and long term control. One can always say the sinkrate is set by thrust and the airspeed is set by elevator, or vice versa -- but at the end of the day both parameters together set the flight path angle. On a near-idle descent at higher altitudes over a longer distance, I can set the power so that the green altitude range arc on the ND sits over my descent target while I maintain the airspeed with my elevator. I have enough time to adjust the thrust for the desired flight path angle. At lower altitudes and in tighter corridors, like on approach, I could apply the same principle (easy on smaller aircraft), but for quick corrections in such critical phases it's better to set the path primarily by elevator and airspeed by thrust, i.e. short term path corrections quickly by elevator, and short term airspeed corrections quickly by power. The other way round it wouldn't work so quickly :-) -- Anyway, for the AFDS: VNAV_PTH and V/S and G/S and FLARE are always flight path on elevator and airspeed on throttle. The AFDS cannot mix it. A human pilot can.

[Martin Baker]

Interesting question. Which translates to:

Does the AP assume 'speed by elevator' or 'speed by thottle' in the later phases of the approach?


Hoppie

I suppose what I was getting at is, can the human mind do a better job than the auto throttle, which I think tends towards overcontrol in these extreme cases? (It treats each velocity change literally, rather than the human: "ok, it's going that way now and in 2 seconds it will go the other way, so i'll Just keep a reasonably constant thrust and not panic!"

[Hardy Heinlin]

The question is aircraft type specific. E.g. the autothrottle of the 777 and other FBW types is much smarter than that of the 744.

[Jeroen Hoppenbrouwers]

"Turbulence mode" on older systems is sort of a similar approach. Either widen the target band or slow down the response.