Avoiding overspeed during slats/flaps retraction involves a combination of procedures, pilot attention and coordination, anticipation of configuration changes, and a thorough understanding of the limit speeds. ARS and Alpha Lock ensure safe slats/flaps retraction during heavy weight takeoffs.
It is crucial to respect VMAX during slats/flaps transition to prevent overspeed warnings and ensure safe operation. This information helps pilots manage slats and flaps effectively during takeoff at heavy weights, ensuring both safety and compliance with aircraft performance limits.
Automatic Retraction System (ARS)
| ARS Activation | ARS Indication |
| When in CONF 1+F and the IAS reaches 210 knots (or 215 or 225 knots on some A321 models), the ARS activates, automatically retracting the flaps to 0°. | The PFD will show the flap setting change from VFE CONF1+F to VFE CONF 1. The flap lever can be selected to 0 once the aircraft accelerates above S speed. If IAS decreases below VFE CONF1+F, the flaps will not extend back to 1+F. |
Alpha Lock Function
Purpose: Prevents slat retraction at high angle of attack (AOA) or low speed when the flap lever is moved from Flaps 1 to Flaps 0.
Alpha Lock Indication
An “A. LOCK” indication will pulse above the E/WD Slat indication. Slats retract when AOA and speed fall within normal values and this inhibition is removed. If the Alpha Lock function is triggered, the crew will continue with the scheduled acceleration, allowing further slat retraction. SFCC use correct AOA or speed info from ADIRU to inhibit slats retraction. Retraction is inhibited when AOA is above 8 degree or speed less than 165 knots.