To calculate times in navigation, the Groundspeed (GS) is required, which is equal to:

• GS = TAS + Tailwind component, or
• GS = TAS - Headwind component

For this question, GS = TAS - Headwind component = 105 kt - 12 kt = 93 kt.

The ground distance covered is 75 NM. Thus, the flight time required is: Ground Distance / GS = 75 NM / 93 kt = 0.8 hr or 00:48 approximately.

Thus, the Estimated Time of Arrival (ETA) is: ETD + Flight time = 12:42 UTC + 00:48 = 13:30 UTC.

NOTE:

To convert the time from HH:MM to a decimal form, proceed as:

• 0.8 hr = 0.8x60 min = 48 min.