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

22) In Intrumental landing system, the middle markers are located

23) The size of landing area for multiengined helicopters operating under 1FR conditions is

24) The centre to centre spacing of heliport lighting along the periphery of landing and take off area should be

25) The slope of the obstruction clearance line from the boundary of the heliport should be