Question

The primary purpose of the Windrose diagram is for the design of

• A. length of a runway.
• B. orientation of a runway.
• C. width of a runway.
• D. gradient of a runway.

Hint:

Windrose diagrams plot wind direction and duration, used with a crosswind template to align the runway into the prevailing wind.

Answer 1

The Correct Option is B

The Windrose diagram is a wind direction and wind speed frequency chart used specifically in airport planning. Let's check what each option claims it is used for.

1. length of a runway: Runway length comes from the aircraft's takeoff and landing distance requirements, corrected for airport elevation, temperature and effective runway gradient. Wind direction data does not decide how long the runway needs to be, so this is wrong.
2. orientation of a runway: Aircraft need to land and take off as close to head-on into the wind as possible to reduce ground run and keep the crosswind component within safe limits. The Windrose, combined with a crosswind template, is exactly the tool used to find the direction that keeps crosswind within the allowable limit for the largest fraction of the time, usually a target of 95 percent wind coverage. This is the direct, primary use of the Windrose diagram.
3. width of a runway: Runway width is set from the wheel track and wingspan of the critical design aircraft plus safety clearances, again nothing to do with wind direction.
4. gradient of a runway: The longitudinal gradient of a runway is governed by drainage needs and permissible grade change limits for aircraft operation, not by wind direction.

Since the Windrose plot is built entirely from wind direction, duration and speed data, and its only design application is choosing the best runway alignment against the prevailing wind, the correct use is fixing the orientation of the runway.

Let's summarize:

• Windrose diagram: records wind direction, duration and speed at the airport site.
• Used with a crosswind template to select the runway direction with least crosswind interference.
• Runway length, width and gradient are each fixed from separate, non-wind criteria.

So the primary purpose of the Windrose diagram is the orientation of a runway, option (B).