Every one of us was mesmerized by giant aircrafts flying high in the sky when we were kids. Running out to the open space to see the helicopter/ airplane flying above and waving our hands so as to say good bye. Crazy childhood times, so innocent so fragile and so much full of curiosity.
I was flying from Trivandrum to Delhi and in my Sherlock-needs-to-notice mood I took my seat in the aircraft and was peeping out from that small airplane window. What caught my interest was not the giant airbus which was taking me to my destination but the ground which was paying way for it to take off. Yes I am talking about runways!
Did you ever notice the numbers stands along the runways, what do they really mean? Well for us they are just mearg numbers but for pilots they are more than that. After lot of search on net, reading from one page to other, navigating from one site to other I finally understood the basic relevance of the runway numbers.
How good it will be if all the information that I got from 30 – 40 sites will be listed in just one page, in a simple to understand language. So here it is a basic introduction about what runway numbers really means:
The numbers signifies the direction(heading) of the runway.
Runways are numbered between 01 and 36.On a compass North is 360°, East is 90° South is 180° and West is 270°. You cannot have a runway zero.
Since a runway can be normally used in two directions (there are always exceptions), it will have a second number which will always differ by 18 (180° or half way across the compass). In India most airports have an east-west runway 09-27.
Certain ultra-large airports most notably Atlanta Hartsfield-Jackson (ATL), Los Angeles International (LAX) and Dallas-Fort Worth (DFW) have more than three parallel runways. In such cases the traditional left, centre, right designations cannot be used and the the runway identifiers are shifted by 10 degrees or 1 digit on the runway number). At Dallas-Fort Worth, there are five parallel runways, named 17L, 17C, 17R (on the east side of the airport), and 18L, and 18R (on the west side of the airport), even though all five runways are oriented at a heading of 175.4°.
For normal fixed-wing aircraft it is advantageous to perform take-offs and landings into the wind. This is to increase the speed of air over the wings i.e. flying speed, at a relatively lower ground speed which reduces the actual take-off or landing distance needed. Thus, runway orientations are decided on the historical winds and directions.
In a nutshell:
Runway numbers indicate the direction of heading. All runways are numbered between 1 and 36. 360 degree(runway 36) is North, 180 degree (runway 18) is south, 90 degree (runway 9) is east and 270 degree (runway 27) is west. These are chosen for takeoff or landing depending upon the direction of wind. In case of parallel runways they are differentiated as left, Right or Center e.g. 36L, 36C, 36R. Each runway has two names depending upon the direction you are heading to. E.g. if runway 34 is north, (34-18) runway 16 will be south i.e same runway will be named as 34 and 16 depending in which direction is it being used. There is always a difference of 180 degree or 18 numerical digit between direction of runway