ARS and FLRS — the Two Automatic Flap-Overspeed Protections
Two systems automatically retract the flaps to protect them from overspeed, at opposite ends of the flap range: the ARS (Automatic Retraction System) pulls 1+F back to 1 at 200 kt, and the FLRS (Flap Load Relief System) pulls CONF 2/3/FULL back one notch on a VFE exceedance. Both keep the slats out while shedding flap. (The slats' own protection — the alpha/speed lock — does the opposite and is in 29.)
FLRS: Only available in CONF 2, 3, or FULL. When activated, the system retracts the flaps to the deflection corresponding to the next retracted lever position. Auto retraction of the flaps only occurs in case of VFE exceedance (VFE +2.5 kt). — FCOM DSC-27-30-10
1. ARS — automatic retraction of 1+F to 1 at 200 kt
Per FCOM DSC-27-30-20, the CONF 1 vs 1+F behaviour is the ARS:
- selecting FLAPS 1 from clean above 100 kt → CONF 1 (16°/0° — slats only, no flaps);
- selecting FLAPS 1 below 100 kt (or after CONF 2+ was selected) → CONF 1+F (16°/8°, droop 5°);
- in CONF 1+F the flaps automatically retract at 200 kt → CONF 1;
- after that retraction, 1+F is unavailable until speed ≤ 100 kt (unless CONF 2+ was previously selected).
[!warning]- Lever position 1 is two configs, and the flaps self-retract at 200 kt The lever doesn't change, but the surfaces do: 1+F gives flaps + slats for takeoff, and the ARS automatically retracts the flaps at 200 kt to CONF 1 (slats only) (FCOM DSC-27-30-20) — protecting the flaps from overspeed as the aircraft accelerates while keeping the slats out. This is why, on a takeoff at FLAPS 1, you see the flap symbol retract on its own near 200 kt with the slats staying.
2. FLRS — flap load relief in CONF 2/3/FULL
Per FCOM DSC-27-30-10, the FLRS is available in CONF 2, 3 or FULL. On a VFE exceedance (VFE +2.5 kt) it retracts the flaps to the next retracted lever position's deflection:
- CONF 2 → CONF 1* (20° slats / 8° flaps);
- CONF 3 → CONF 2* (23° slats / 14° flaps).
If speed reduces below VFE (VFE −2.5 kt), the flaps return to the selected position. The CONF 1*/2* are reachable only by FLRS. The ECAM shows a flashing green F RELIEF, and an OVERSPEED warning appears at VFE +4 kt.
[!warning]- FLRS sheds flap but not slats — and reverses when you slow down On a VFE exceedance the FLRS retracts only the flaps one notch (slats stay at the higher setting: CONF 2→1* keeps slats at 20°, CONF 3→2* keeps slats at 23°) — relieving flap load while preserving lift from the slats (FCOM DSC-27-30-10). It is reversible: slow back below VFE−2.5 and the flaps return. The green pulsing F RELIEF (and pulsing flap box on the EWD) tells you it is active.
3. The EWD messages — F RELIEF, F LOCKED, A LOCK
Per FCOM DSC-27-30-20, the high-lift EWD symbols distinguish the systems:
| Message | Meaning |
|---|---|
| green pulsing F RELIEF | FLRS active (flap load relief) |
| amber F LOCKED | flap WTB applied (30) |
| green pulsing A LOCK | slat alpha/speed lock active (29) |
| amber S LOCKED | slat WTB applied |
| amber F / S symbol | flap/slat system failure, or low pressure (flaps: yellow+green; slats: blue+green) |
[!note]- Three different "the surface isn't where the lever says" messages (integrative synthesis) Don't confuse them: F RELIEF / A LOCK (green pulsing) are automatic protections doing their job — flap load relief and slat-retraction lock; F LOCKED / S LOCKED (amber) are WTB failures that have locked the transmission (30). Green pulsing = protection working; amber = something is broken. The flap/slat box pulses green when FLRS/alpha-lock is active.
4. Counterintuitive points
[!warning]- ARS protects the low-config flaps (1+F→1 at 200 kt); FLRS the high-config flaps (2/3/FULL on VFE) Two flap-overspeed protections at opposite ends of the range, both keeping slats out (FCOM DSC-27-30-10/-20).
[!warning]- CONF 1*/2* exist only via FLRS You cannot select them with the lever — they appear only when FLRS retracts a notch (FCOM DSC-27-30-10).
Self-test
[!note]- Q1. What does the ARS do, and at what speed? Selecting FLAPS 1 gives 1+F (low speed) and the flaps auto-retract to CONF 1 at 200 kt (slats stay out).
[!note]- Q2. When does the FLRS activate, and what does it do? On VFE +2.5 kt in CONF 2/3/FULL — retracts flaps one notch (2→1*, 3→2*), slats stay; returns at VFE −2.5.
[!note]- Q3. How are CONF 1* and 2* obtained? Only by FLRS auto-retraction — not selectable by the lever.
[!note]- Q4. F RELIEF vs F LOCKED? F RELIEF (green pulsing) = FLRS active (normal protection); F LOCKED (amber) = flap WTB applied (failure).
Key takeaways
| Point | Detail |
|---|---|
| ARS | FLAPS 1 → 1+F (low speed) or CONF 1 (clean >100 kt); flaps auto-retract 1+F→1 at 200 kt |
| FLRS | CONF 2/3/FULL; VFE +2.5 → retract one notch (2→1*, 3→2*), slats stay; return at VFE −2.5 |
| CONF 1*/2* | FLRS-only (20/8 and 23/14) |
| Messages | green pulsing F RELIEF (FLRS) / A LOCK (alpha lock); amber F/S LOCKED (WTB) |
| Overspeed | OVERSPEED warning at VFE +4 kt |
References
- FCOM DSC-27-30-10 (Flaps and Slats — FLRS) — available CONF 2/3/FULL; on VFE exceedance (VFE +2.5 kt) retracts flaps to next retracted lever position (CONF 2 → 1* [20/8], CONF 3 → 2* [23/14]); returns at VFE −2.5 kt; CONF 1*/2* only via FLRS; flashing green F RELIEF on ECAM; OVERSPEED warning at VFE +4 kt.
- FCOM DSC-27-30-20 (Controls and Indicators) — ARS: FLAPS 1 from clean above 100 kt → CONF 1 (slats only), FLAPS 1 below 100 kt (or after CONF 2+) → CONF 1+F, flaps auto-retract at 200 kt → CONF 1, 1+F unavailable until ≤100 kt unless CONF 2+ previously selected; EWD symbols F RELIEF (FLRS, green pulsing), F LOCKED / S LOCKED (WTB, amber), A LOCK (alpha/speed lock, green pulsing), amber F/S on system failure or low pressure (flaps yellow+green, slats blue+green).
Independent study material, not an Airbus publication and not endorsed by the manufacturer. Always defer to the current operator FCOM, FCTM, and QRH for operational use.