From our supplementary procedures, ch16 adverse weather -
Approach and Landing
If ice formations are observed on the airplane surfaces, (wings,
windshield wipers, window frames, etc.):
VREF ............................................................ ..... Add 10 knots PF
This ensures manoeuvring capability.
Note: The combined airspeed corrections for ice formations, steady
wind and gust should not exceed a maximum of 20 knots.
Note: To prevent increased landing distance due to high airspeed,
bleed off airspeed in excess of VREF+5 knots+gust correction
when below 200 feet AGL. Maintain the gust correction to
touchdown.