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hismaimai9999
7th Nov 2018, 07:03
As per the title. What is the perceived wisdom? My guess, good pack back on at selection of MCT?

Oh, and overweight landing in Flap 3, pack back off at about 1500' (avoids ecam blah during landing inhibit) and straight to Flap1+F if go-around initiated?

vilas
7th Nov 2018, 19:57
Oh, and overweight landing in Flap 3, Why would you be flap 3 in overweight?
Use the ECAM flap setting, if required for abnormal operations. In all other cases:
‐ FULL is preferred for optimized landing performance.

Cough
7th Nov 2018, 20:10
Why would you be flap 3 in overweight?

If the QRH overweight landing checklist directs you to (Above the Conf 3 G/A weight for alt/temp)

FlightDetent
7th Nov 2018, 22:25
hismaimai9999 (https://www.pprune.org/members/484417-hismaimai9999) One after MCT, and the p.b. for the other one as well. The STS wording that follows certain EO configurations makes better sense then. It doesn't hurt and you keep the original drill.

Fursty Ferret
8th Nov 2018, 11:21
After thrust reduction. If the engine is still at flex or TOGA power, the pack will operate normally but will significantly degrade the bleed margin on the engine.

vilas
8th Nov 2018, 16:57
If the QRH overweight landing checklist directs you to (Above the Conf 3 G/A weight for alt/temp) Cough can you state from your QRH the weight for Conf 3 for worst alt/temp combination?

vilas
8th Nov 2018, 17:03
FF
After thrust reduction. If the engine is still at flex or TOGA power How's that possible? On EFATO you accelerate retract flaps resume climb only then you reduce thrust. What's the problem if you put pack on?

lurkio
8th Nov 2018, 19:35
Come on Vilas, normally you are the fount of all knowledge here. Have you just woken up or forgotten your glasses?
The flap 3 was a simple question answered by Cough and as for Fursty Ferret's answer there is a full stop after reduction which clearly separates the short answer from the explanation as to why.
Hopefully normal service resumed later eh?

Cough
9th Nov 2018, 03:34
Thankyou Lurkio...

Vilas - A320 CEO with IAE engines.

8000'/35C - 65T (Hot day in Mexico City then....)

Hope that helps....

vilas
9th Nov 2018, 03:49
Hi lurkio
The OP appeared to suggest flap3 as a norm for OW landing. My question to Cough was a bit tongue in cheek to say that it's very rare that you will be limited to flap3 (To add some fun). I did miss the full stop so was wondering if I missed something. Thanks

Jonty
9th Nov 2018, 06:56
It’s interesting, but usually I read these 320 posts as covering the 320 family of aircraft.
Lets just say the 321 is a very different proposition in this regard.

Cough
9th Nov 2018, 09:34
Yup, got where you are coming from, but that's for some parts of the world. Others (like South America and China) have multiple high altitude airfields where both the destination and alternate are high. That's why I didn't just quote from the QRH, I did so with context. Last time I was at MMMX there were multiple A320's operating.... And Jonty has a real point too as the A321 has the same weight limit as the A320 at that altitude.

But I agree, Flap 3 shouldn't be the Norm...

oceancrosser
10th Nov 2018, 06:21
Why are Airbuses operated more or less packs off for take-off? Are the packs also switched off for landing in case off go-around? What is the reasoning? Hardly lack of thrust...

Fursty Ferret
10th Nov 2018, 08:42
Reduced engine wear.

pineteam
10th Nov 2018, 11:26
Also for fuel saving. It’s all about $$.

Jetjock330
11th Nov 2018, 07:29
If you divert somewhere after first single engine approach, you need the "pack on" to pressurize for flight above 10000ft!

Bus Driver Man
11th Nov 2018, 13:56
Why would you be flap 3 in overweight?
Didn't you give the answer to your own question?
Use the ECAM flap setting, if required for abnormal operations.

Also, the table in the QRH is for a 2.1% gradient. What if you need more than 2.1%? A heavy A321 can be limited at some airports.
What if you don't have the required gradient for a go-around with config 3, but you have the required gradient with config 1+F? Would you land with config full anyway and have a back-up plan in case of a single engine go-around or would you land with config 3 without having to worry about your go-around gradient in case of a single engine go-around?
Genuine question. Or am I just overthinking this?

Bus Driver Man
11th Nov 2018, 14:05
Why are Airbuses operated more or less packs off for take-off?
Depends on the company.

A320 FCOM:
PACK 1 and 2........................................................... ............................................................ .AS RQRD
Consider selecting packs OFF, or APU bleed ON. This will improve performance when using TOGA thrust. In case of a FLEX takeoff, selecting packs OFF or APU bleed ON will reduce takeoff EGT, and thus reduce maintenance costs. The use of flex thrust may reduce maintenance costs. The effect is particularly significant with the first degrees of FLEX. Use of APU bleed is not authorized, if wing anti-ice is to be used.

FlightDetent
11th Nov 2018, 17:13
@oceancrosser: because the PACK OFF/ON drill is very simple, thus for economical reasons it is a very common operating technique. Well documented by the manufacturer.

@Bus Driver Man: Agreed. Moreover, the 2.1% gradient is a certification requirement FAR/CS 25 for approach climb (G/A conf, L/G UP, OEI). The actual REQUIRED performance is 2.5% to keep yourself inside (well, above is a better word :E) the premises of PANS-OPS ICAO Doc 8168 - obstacle clearance for the missed approach segment.

Properly done books / EFB should have the QRH table i and EFB application modified to 2.5 per cent. Let's not start about OEI ACC ALT on G/A. :\