17) Calm period is the percentage of time during which wind intensity is less than

18) For determining the basic runway.length, the landing case requires that aircraft should come to a stop within p % of the landing distance. The value of p is

19) According to ICAO, all markings on the runways are

20) Runway threshold is indicated by a series of parallel lines starting from a distance of

21) The width and interval of transverse centre line bars along the extended centre line of runway, in approach lighting system are