The ground speed of an aircraft with an indicated airspeed of 150 knots and a headwind of 30 knots can be determined only if which information is known?

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To determine the ground speed of an aircraft, it is essential to account for both its indicated airspeed and the effects of the wind. In this case, the indicated airspeed is 150 knots, and there is a headwind of 30 knots.

The relationship between ground speed, indicated airspeed, and wind is described by the formula:

Ground Speed = Indicated Airspeed ± Wind Component

When there is a headwind, the wind component is subtracted from the indicated airspeed. However, to accurately relate indicated airspeed to ground speed, knowing the true airspeed becomes critical.

Indicated airspeed, which is what the pilot reads on the airspeed indicator, is affected by air density and temperature at altitude. This means that, without knowing the true airspeed, which compensates for these factors affecting the indicated reading, the exact effect of the headwind cannot be fully understood or calculated. The true airspeed is necessary to convert the indicated airspeed to ground speed reliably, particularly at varying altitudes and conditions.

Thus, by knowing the true airspeed, one can accurately compute the ground speed given the wind conditions. None of the other options (altitude, temperature, or wind direction) directly relate to converting indicated air