Question

Nacelle anti-ice MUST BE ON during all ground and flight operations when icing conditions exist or anticipated except when temp is ____?

1) -50 degrees Celsius or below
2) -40 degrees Celsius or below
3) -30 degrees Celsius or below
4) -20 degrees Celsius or below

Answer 1

Nacelle anti-ice systems should be on when icing conditions are present, except at temperatures of -40 degrees Celsius or below, where the moisture content is too low for ice to form.

Step-by-step explanation:

The subject question relates to the operation of nacelle anti-ice systems on aircraft. Such systems must be on during ground and flight operations when icing conditions are present or anticipated, to prevent ice from forming on the nacelles, which are the enclosures for the aircraft's engines. However, there is an exception to this requirement.

The anti-ice systems do not need to be used when temperatures are so low that the formation of ice is highly unlikely.

In the absence of make and model-specific guidelines from an aircraft's operating manual, a general aviation standard could be applied, which typically suggests that icing conditions are not prevalent when the temperature is -40 degrees Celsius or below. This is because at these extreme temperatures, the moisture content in the atmosphere is very low, reducing the probability of ice formation.