Winds Aloft (FD)

This is a mini-lesson. AC 00-45 has a very good explanation of how to use and interpret an FD. Page numbers cited here use AC 00-45E (although AC 00-45G is now available and can be downloaded for free from the FAA).

Definitions

The Winds Aloft Forecast (FD) provides a forecast of the wind direction, wind speed, and temperature.

Objective(s)

Understand how the FD applies to helicopter operations (and use AC 00-45 to understand and interpret the information provided on the FD).

Description

1. AC 00-45E reference
2. FD highlights
3. What an FD can tell you about turbulence (see Real-life Experience section)

Instructional aids

• AC 00-45E or AC 00-45F are recommended
• The student should be provided with several sample FDs to interpret in preparation for the FAA written exam.

Content

AC 00-45

Pick up or download Aviation Weather Services from the FAA–this publication provides the clearest explanation of how to use and interpret the FD.

Winds and Temperatures Aloft (FD) Highlights

• Issued every 6 hours
• Format: DDSSTT where wind direction (DD), wind speed (SS), and temperature (TT)
• Wind direction is TRUE, wind speed is in knots, and temperature
• No winds are reported within 1500′ of the station, and no temps are given within 2500′ of station
• 9900 = wind light (<5 knots) and variable
• Wind direction codes above 51 and 86 indicate winds over 100 knots. Subtract 50 to get the wind direction, and add 100 to the wind speed

Real-life advice and experience

• Winds aloft forecasts and predicting turbulence: expect vertical wind shear when winds on the FD increase >6 knots per 1000 ft.

Additional resources

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