For A300 Drivers

[reverserunlocked]

One, is it usually flown with the AT on even when being manually handled, like the 320 series and onwards?

Second, what's the thinking behind the pre-set function? I know you can preset green dot plus 20 to target in case of an engine out after takeoff, but when else might you use it? Also how to you actually get it to target the pre-set speed? Presumably come out of prof mode?

Let's throw one more in - is the prof mode complete garbage? The crew I watched used it for the climb but descent was pretty much VS/LVCH. Seems not very trustworthy.

Thanks!

[InSoMnIaC]

One, is it usually flown with the AT on even when being manually handled, like the 320 series and onwards?

Usually A/THR remains on even in manual flight. Manual thrust is acceptable but not required.

Second, what's the thinking behind the pre-set function? I know you can preset green dot plus 20 to target in case of an engine out after takeoff, but when else might you use it? Also how to you actually get it to target the pre-set speed? Presumably come out of prof mode?

Preset only works with basic modes. Not profile mode. The aircraft targets the preset speed when a Pitch mode change occurs (eg from SPD to ALT, or from VS to SPD.. Except that a change from SPD to VS will not activate the preset speed). Preset speed also becomes active when used to transition into a Mach No or Speed during climb or descent - see item 2 below. Some uses of preset function are listed below:

1. Takeoff - as u mentioned. Preset GD+20 or 250 (which ever is higher). This will allow the aircraft to accelerate towards GD when Alt Hold is selected at the eng out accel Alt. This assumes that SRS has not changed to P.CLB. If this happens, the speed window will blank and the preset will be cleared.
2. While climbing out in speed mode and you want to transition to a mach number. Eg climbing at 300kts and u want to transition to Mach .78. To do this, climb at 300 in lvl chg (or vs) then press preset and changeover from speed to mach and set 0.78 in the speed window. The aircraft will maintain 300 and transition to 0.78. This technique can also be used in descent.. ie for transitioning from Mach to Speed.
3. Although less common, it can be used to climb or descend at one speed/mach and cruise at another. Eg say u want to descent at 300kts but slow to 250 on level off.
4. After go around is commenced, you can preset the target speed for acceleration so that when level change is selected, it will automatically speed up.

Let's throw one more in - is the prof mode complete garbage? The crew I watched used it for the climb but descent was pretty much VS/LVCH. Seems not very trustworthy.

profile mode is not garbage however it has its limitations. Using it in climb and cruise is fine however descent in profile mode can be tricky if you are not familiar with it. As a general rule, profile mode can be used for descent however it should be disengaged when a lateral or vertical revision is made to the flight plan, or if the active lateral mode is not NAV. This is because it can cause a level off or even climb to capture the recalculated profile.



The Final approach function (if installed) is very useful for NPA. Just load the NPA in the FPLAN and enter the MDA in the Approach page. Aim to intercept the profile from below in ALT mode. Arm Profile and configure towards VAPP. When P.SPD| P.DES engages, it will target VAPP



Hope this helps

[reverserunlocked]

Originally Posted by InSoMnIaC

Hope this helps

Thanks for that, very informative. Interesting how the A300 will do a profile climb or descent when on a heading, whereas Airbus disabled this for the A320.

Consideing its age, the A300 was quite ahead of its time though.