vilas
Hello there,
(For Direct Law Airbus recommends use of manual thrust.)
The technical reasons for using Selected speed for VAPP with LDG with S/F jammed are the following:
1. The selected LDG CONF on the MCDU may not correspond with the actual Flaps lever position for landing. This could limit your Managed Speed target to F, which could be above your abnormal VAPP. (i.e. no deceleration to Vapp tgt)
2. VFE exceedance, due GSmini, whenever the actual CONF (due jam) is higher than the Flaps lever position for landing. (i.e. the actual VFE is lower than the one displayed on the PFD speed tape)
It is true that high-energy during last stage of final approach can be avoided by not having GSmini, although for the A330, A320neo and A350 with k-factors significantly reduced this is much less of an issue than with the A320ceo.
Indeed, in the case of a G/A with S/F jammed, selected VAPP will become managed upon SRS engagement. Speed will have to be Pulled upon reaching Acceleration Altitude. (Top-tip: Speed can be inserted as a SPD constraint in the missed app, as a reminder)