If the wind direction is from 240° at 9 knots and varies from 210° to 260°, how should this be formatted for transmission?

The correct format for wind reporting in aviation weather observations typically follows specific conventions. When reporting wind direction and speed, the direction is given in three digits, followed by the wind speed in knots. For a steady wind coming from 240° at 9 knots, the report would be formatted simply as 24009KT.

In cases where wind direction is variable, it is standard to include the range of directions. Therefore, when indicating that the wind is varying between 210° and 260°, the correct format would include this range. The proper reporting would incorporate this variability, leading to the option that explicitly details both the wind direction and its variance, which is not just a straightforward listing of the direction and speed.

Thus, while 24009KT is correct for a steady wind, it doesn't provide the necessary information regarding the variability of the wind direction. Including the range in conjunction with wind speed and direction conveys more information necessary for flight operations.