Hello 320P
The following is from our QRH checklist for overweight landing.
"– FULL is preferred for optimized landing performance.
–
If the aircraft weight is above the maximum weight for landing in CONF FULL (given in the table below), use CONF 3 for landing.
In all cases, if landing configuration is different from CONF FULL, use
CONF 1+F for go-around (select FLAP lever to 1). This will ensure the required go-around performance is achieved."
So, it's all about the go-around performance . If you are under the max weight for flap FULL then the go-around performance considerations will be met in Config 3. If you are over that weight you must go to Flap 1 to ensure the go-around performance considerations are met.
best regards,
Bruce Waddington