A320 ZigZag on Approach!

[Guest BMI701EGCC]

Good monrning Avsim,Situation...Aircraft: PSS/iFDG merge A320-200 British AirwaysSTAR: Bovingdon 2AProblem....i set everything up fpr the final approach phase for 27L at London heathrow, ie activated app phase, checked speeds, flaps config etc..I was on a radial hdg of 137 from BNN VOR at 2,500 to intercept the LOC*. I set the crs on the RADNAV page to 273 as stated on the V ILS approach chart for 27L(the FMGS automatics had 275 for the final crs for some reason). So as i captured the LOC* i set the hdg on the FCU to 273 for the final crs, the lining up of the RWY was the best ive every exercised(maybe because i approach 40degrees out from final??). I continue decending on the ILS but then the plane starts to zigzag dramatically, thus making the speed diviate, when i was in flap full config i selected from managed speed, which was about 140 knts but from some reason it wanted 200knts!?!Anybody know why this happened, it has never happened to me before, zigzagging and a great capture normally it would just pass the LOC* and intercept at about 6.0DME.(should th a/c just capture pefectly at the first turn?)BMI701EGCCScott Waterworth

[Guest NormanB]

Scott,I have no experience of this merge and naturally PSS don't support it. Possibly it could be better answered by the BAW Virtual Airbus Training Captain since I believe the merge is something he is familiar with.