De-Icing Procedure

Question 1

What visual cues might you see that show the need for the aircraft to be de-iced

Answer 1

Any evidence of frost, slush, snow or ice deposits on the aircraft surfaces

Question 2

What is Radiation Cooling?

Answer 2

Usually occurs on a clear night where the aircraft surfaces can cool a further 4 degrees due emitting long wave radiation. Since there is no sun emitting short wave radiation (heat)

Question 3

What is Rime Ice

Answer 3

Ice formed by freezing fog or cloud droplets on cold surfaces

Question 4

What does LOUT stand for

Answer 4

Lowest Operational Use Temperature (freezing point of de-ice/anti-ice fluid plus buffer of 10 degrees

Question 5

What is a Pre-Departure check

Answer 5

Check by PIC to determine if de-icing/anti-icing is required. Followed by another check after procedure completed to validate HOT

Question 6

What is HOT

Answer 6

Hold overtime: estimated time for which anti-icing fluid will prevent the formation of ice in the aircraft surfaces

Question 7

When do you apply cold weather altimeter correction

Answer 7

Corrections to altitude is not required if under radar control. No corrections are needed for reported temperatures above 0°C or if the airport temperature is at or above the minimum published temperature for the procedure being flown.

The DH/MDA/DA must be corrected for temperature for the approach, otherwise you could reach minimums and actually be below the obstruction clearance altitude.(due to altimeter error)

Question 8

When can Clear Ice form

Answer 8

During cold soaked conditions. Heavy freezing has been found during drizzle or rain with OAT as high as 14 degrees.

Question 9

Describe the one step de-icing/anti-icing procedure

Answer 9

Only used in light icing conditions, HOT starts when the procedure commences

Question 10

What is the two step de- icing/anti-icing procedure

Answer 10

Used for highly contaminated surfaces when OAT is low and heavy precipitation.

Step 1: hot mixture of water & fluid using type 1 fluid

Step 2: carried out 3 mins after the first step using de-icing/anti-icing fluids. HOT starts after the commencement of the second step

Question 11

What de-icing/anti-icing codes must the flight crew receive

Answer 11

1. Element A: “Type I”, “Type II” or “Type IV”.
2. Element B: specify the percentage of de-icing /anti-icing fluid In the fluid/water mixture, e.g. “100” for 100% fluid, “75” for 75% fluid and 25% water (not required for Type I fluid).
3. Element C: specify in local time, in hours and minutes, the beginning of the final de-icing/anti-icing step, e.g. “1330”.
4. Element D: specify date as day, month, year, e.g. “20 March 1999” (only required for record keeping and optional for crew notification).

5 Optional: The complete name of the anti-icing fluid i.e. brand name.

Question 12

How is the HOT calculated?

Answer 12

Aircraft Ground De/Anti Icing companies provide tables of Holdover Times for different fluids and prevailing conditions. They published tables regularly and provide an indication as to the time frame of protection that could reasonably be expected in each situation

Question 13

What are the time range values show in the HOT tables?

Answer 13

The Tables contain elapsed time ranges which represent indicative maximum holdover times. The lower limit of the given time span indicates the estimated time of protection during moderate precipitation of the type stated; the upper limit indicates the estimated time of protection during light precipitation of the type stated.