A320 Normal Operation Questions

[Huntergreed]

I’m trying to learn my way around the A320 and have some questions about typical operation (of course some of these questions might not be answerable by forum members (quite specific!) but if anyone has any ideas I’d appreciate it )

Under what circumstances would FLEX be used to takeoff thrust as opposed to the standard TOGA setting? Why would this be used, is there any benefit?

Is the “top of descent” marked on the NAV (calculated from the flightplan inputted on the MCDU) the exact point where the descent starts, or do pilots normally start the descent before/after this (before I would imagine would allow for a hold before ILS establishment).

Is there a “normal point” for pilots to take manual control over the Autopilots once established on the ILS or is this pilot discretion?

When/why would a FLAPS 3 landing be used over a FULL CONFIG landing (which I understand is the standard practice?)

Thanks

 

[Ted633]

I'm a Boeing man unfortunately, not Airbus (yet!), so I can't answer all, but I'll have a go.

A FLEX option for take off thrust is much more desirable to the airline than TOGA. FLEX setting is calculated prior to flight, taking into account the length of runway, conditions and weight of the aircraft. FLEX will always be a lower thrust setting than TOGA, resulting in a longer takeoff run. However, fuel economy is improved and wear on the engines reduced.

Pretty sure there isn't a normal point for the pilot to take over on approach, however the most common one is not at all!

Can't answer the others as I am not familiar with Airbus terminology, but I hope the above makes sense.

 

[rf_ioliver]

Two posts from PPRUNE on Flaps 3 vs Full ... basically flaps 3 gives you more energy to play with, ie: higher speed, for gusty/tubulent conditions

Airbus - Flap FULL or Flap 3?? - PPRuNe Forums

Questions - Airbus - Flap FULL or Flap 3?? - General question: Under what circumstances would you use Flap 3 for landing as opposed to Flap FULL? And why?? Obviously this question would apply to any aircraft where you have a choice of landing flap settings. Normally most people I have seen will...

www.pprune.org

A320 handling in Flap 3 vs Flap Full - PPRuNe Forums

Questions - A320 handling in Flap 3 vs Flap Full - Hi I have been in the left seat of A320s for over 10 years and have developed the habit of using Flap 3 and Vapp of Vls +10 for an approach in expected turbulent or possible windshear conditions. The reason for doing this is because Airbus says...

www.pprune.org

Another edit from the AVSIM flight sim forums: https://www.avsim.com/forums/topic/212569-when-to-use-flaps-3/

FLEX is generally used to save on engine wear, TOGA is used for specific situations/weather etc.

Descent is generlly controlled by ATC, I guess if you're past your TOD then you might start calling as requesting descent. BAsically the aircraft calculates the optimal flight and displays that.

The switch to A/P or off, depends upon the pilots - if sitting in the front rows of some A320s listening to the A/P disconnect it is probably not too much earlier than minimums on landing sometimes - other times quite early in the descent; similarly for the departure. Of course, there's nothing stopping the pilot flying everything manually. The aircraft is capable of flying a completely automated landing (airport systems permitting etc).

All of the above will of course depend upon airlines' and manufactuer SOPs.

 

[Cloud Strife]

Under what circumstances would FLEX be used to takeoff thrust as opposed to the standard TOGA setting? Why would this be used, is there any benefit?

Generally speaking, FLEX is adapted for the specifics of the airport, whereas TOGA is just full power. If you think about some flights (for example, let's say Prestwick to Dublin) where you've got a very very long runway and a lightly loaded plane, you simply don't need full power.

Is there a “normal point” for pilots to take manual control over the Autopilots once established on the ILS or is this pilot discretion?

Pilot discretion, although some airlines have it in their SOPs that the autopilot should remain engaged as long as possible.

 

[Shaw S Hunter]

Descent is generlly controlled by ATC, I guess if you're past your TOD then you might start calling as requesting descent. BAsically the aircraft calculates the optimal flight and displays that.

Not so much generally as absolutely, a basic principle of flying in controlled airspace. However ATC has plenty of stress involved and controllers will tend to act in a broadly collaborative manner: experience will tell them when to expect a descent request assuming they haven't already issued a suitable instruction.