A320 Go Around
 

In the A320 when we takeoff in Config 3 the flap retraction is directly to Config 1 whereas if the approach is made in Config 3, in case we carry out a missed approach the flaps are retracted only to 2.
Why this difference?

Partly because you're rarely near the ground when retracting flaps after take off and mostly because it's easier to just retract one stage on the go around.

During takeoff or GA in acceleration phase the procedure is same i.e. 3 to 1. It is during initiation of GA you retract only one step from approach setting. There is an exception only for overweight landing where if the approach was made in flap 3 you retract to one in the initiation phase.

Thanks. But why from 3 to 2 during initiation of Go- Around. In the same context, why is it that in some airfields for the same approach there are 2 minimums specified with different minimum approach climb gradient?

I had replied your first question sometime back. Basically it is about knocking off the high drag full flap. Config 1, 2 or three are takeoff configurations so it's not critical or mandatory to retract one step. Reaching lower minimum aircraft travels further so requires higher gradient to prevent penetrating into the obstruction plane.

Is it not also the case that the F and S speeds have slightly different references between take-off case and approach case? 1.18xVs in the former and 14% higher in the latter case (F speed) Therefore the take-off case flap retraction has less margin.

It's an sop that is designed for a safe GA flap setting from any point (GA from conf2 for example) moving one stage reduces drag flap and is a simple procedure. If you went around from full (GA in 3) you're next step would still be flaps 1.

It’s to meet the regulatory climb gradient requirements. These are speed based. 1.23 VS1G versus 1.13etc. Hence the one step configuration change.

Thanks. So how does a pilot decide which minimum ( DA) to use in case of two minimums specified in the chart.

Two minimums will be there for CAT1 and CAT2 or with some unserviceable components of the approach. Depending on the existing situation the appropriate minimum should be chosen.

My home Airport has 2 cat I and 2 cat II minima. The lower minima for each category requires 3.3% go around gradient. If you can make this gradient then you can use the lower minima, otherwise you use the higher one.

Ok but how does a pilot determine if he can make the gradient?

This is the job of company performance engineers. There is Airbus software like PEP or TLO which will calculate everything and that should be incorporated in the SOP.

Slightly expanded version from vilas': It is the job of the LFI to show the pilot how's it done, reading from the charts / using the tools prepared by the Flt Ops Eng team for this task.

There should be charts in the books.

I know that Airbus FlySmart will give you the Approach Climb gradient achievable once expected LW and other parameters are entered, thus allowing a decision to be made wrt the minima scenario being discussed.

It’s worth to note that the approach climb gradient on the Airbus FlySmart assumes a single engine go around as with both engines the minimum landing climb performance is never limiting. FCOM- Performance- Go Around - General.

I saw lots of crews unaware of that and briefed that in case of go around they will fly the EOSID... LOL.

I had the chance to do a single engine go around and landing during base flight ( other engine in idle power) on an A319 at 53T and it still climbs at 1500+ feet per minute.

Approach climb by definition is with OEI in approach configuration while landing climb is with all engines operating in landing configuration. Obviously landing climb is never restricting.

we always apply the lower minima as in the secondary flight plan we have the EOSID ready. 10-7 has a temperature box defining weather the published missed approach is flyable. engineering's job.