weather servicesFAA-published sample question (IRA, Aug 2021)
Decode the excerpt from the Winds and Temperature Aloft Forecast (FB) for OKC at 39,000 feet. FT 3000 9000 12000 24000 39000 OKC 9900 2018+00 2130-06 2361-30 830558
A
Wind 130° at 50 knots, temperature -58 °C.
B
Wind 330° at 105 knots, temperature -58 °C.✓ Correct Answer
C
Wind 330° at 205 knots, temperature -58 °C.
Explanation
The 39,000-foot group is 830558. A direction code over 50 means the speed is 100 knots or more: subtract 50 from the direction and add 100 to the speed (Aviation Weather Handbook 27.2). So 83 - 50 = 33, i.e. 330 degrees, and 05 + 100 = 105 knots. Temperatures above 24,000 feet are always negative, so 58 is -58 degrees C. Reading it as 130 degrees or as 205 knots misapplies this rule.
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