A wind-rose shows the longest line bearing S 45° E (i.e., 135°). What runway numbers should be assigned based on magnetic bearing rounding rules?

Introduction:
Runway numbering is based on the runway's magnetic centerline bearing rounded to the nearest 10°, with the trailing zero dropped. Each physical runway has reciprocal designations separated by 180° (e.g., 13/31).

Given Data / Assumptions:

• Wind-rose longest line bearing: S 45° E = 135°.
• Runway alignment follows dominant wind direction.
• Standard rounding and reciprocal rules apply.

Concept / Approach:

Compute runway number N as round(bearing/10) with the zero omitted. The opposite direction is bearing + 180°, similarly converted to a two-digit number (01–36).

Step-by-Step Solution:

Verification / Alternative check:

Traditional solved examples often map 135° to 13 and 315° to 31, pairing the reciprocal ends accordingly.

Why Other Options Are Wrong:

• 135°, 315°: These are bearings, not runway numbers.
• 13 alone or 31 alone: Runways are paired; both designations apply.

Common Pitfalls:

• Confusing degrees with runway numbers.
• Forgetting reciprocal designation 180° apart.

Final Answer:

both (c) and (d)