The capacity of parallel runway pattern depends upon A. Weather conditions and navigational aids available B. Lateral spacing between two runways and weather conditions C. Lateral spacing between two runways and navigational aids available D. Lateral spacing between two runways, weather conditions and navigational aids available.

The correct answer is D. Lateral spacing between two runways, weather conditions and navigational aids available.

The capacity of a parallel runway pattern is the maximum number of aircraft that can land or take off on the runways in a given period of time. It is affected by a number of factors, including the lateral spacing between the runways, the weather conditions, and the navigational aids available.

The lateral spacing between the runways is the most important factor in determining the capacity of a parallel runway pattern. The closer the runways are together, the more difficult it is for aircraft to land and take off safely. This is because aircraft need to be able to cross the runway without interfering with each other.

The weather conditions also affect the capacity of a parallel runway pattern. In poor weather conditions, such as low visibility or high winds, it is more difficult for aircraft to land and take off safely. This is because aircraft need to be able to see the runway and have enough control over their aircraft to land safely.

The navigational aids available also affect the capacity of a parallel runway pattern. Navigational aids help aircraft to land and take off safely. In the absence of navigational aids, it is more difficult for aircraft to land and take off safely.

Therefore, the capacity of a parallel runway pattern depends upon the lateral spacing between two runways, weather conditions and navigational aids available.