FCOM PRO-SUP-30:
WING ANTI-ICE may either be used to prevent ice formation or to remove ice accumulation from the wing leading edges. WING ANT-ICE should be selected ON whenever there is an indication that airframe icing exists.
It seems a simple procedure, turn it on and leave it on in airframe icing conditions. Apply the Vapp additive and LDR factor.
However, it has been suggested that
leaving it on may result in significant clear ice build up aft of the leading edges.
A technique has been suggested to counter this possibility: Use the Wing Anti-Ice as a de-icing system only, by cycling it on and off at regular intervals.
The problem is, that without data on how long the leading edges take to cool down after Ant-Ice use the technique is at best hit and miss, probably pointless and possibly dangerous. If the Anti-Ice is cycled too quickly it's pointless, excessively long interval potentially dangerous.
Yes the A320 wingtips can be assessed visually from the flight-deck, but not the A321. Not sure about other types.
The variables:
- Bleed Temperature
- TAT
- Size of the supercooled water droplets
Questions:
- What is the normal operating temperature range of Slats 3, 4 & 5 with the Wing Anti-Ice on? Not bleed temp, how hot are the slats.
- How quickly do they cool down, a few seconds, a few minutes?
- Has anyone noticed after landing the build up of clear ice behind Slats 3, 4 & 5?
- Has anyone experienced controllability difficulty in severe airframe icing conditions using the published Airbus procedure?
Cheers