# How can I calculate which runway to use for landing, based on the wind? [duplicate]

I have a project where the user enters the name of the airport. We fetch the wind direction (degrees) for that airport. Then we use the wind direction and the data about the runways at that airport to calculate which runways the planes will land at. What is the best way to do that?

My approach:

Find the compass direction, for instance 90 degrees is equivalent to east. Then, if the direction of the wind is east, the plane will land from the west (to land against the wind).

My question:

How do I calculate which runway the plane will use to land? There are multiple runways at some airports. Do we use runway heading, or runway longitude/latitude, assuming wind is the only factor affecting landing? Is there a mathematical way to calculate which runway the plane will use? I am asking because I will have to do some calculation to accurately give that answer to the user.

Any expert/aviation help would be greatly appreciated.

Also, I am using the airports and runways table from ourairports.com/data.

Also, what do HE and LE mean in the context of runways?

The name of a runway is a number indicating its direction in tens of degrees.1 For example, to land west-to-east, use runway 09.

Generally, each runway paving may be used in either direction, and the physical paving actually contains two logical runways, running in opposite directions. Only one of these logical runways is allowed to be in use an any time.2

The two logical runways on a paving have names that differ by 18. Thus a paving aligned due east-west will contain logical runway 09 and logical runway 27.

The information you will need about each airport is simply a list of the available runways and their lengths. You will also need the minimum runway length required for your aircraft to land.

To determine the best runway to land on, divide by the wind direction by ten and use the runway that is long enough whose name is closest to the result.

Example: An airport has runways 04 (1200'), 09 (5000'), 15 (5000'), 22 (1200'), 27 (5000'), and 33 (5000').3 Your airplane needs 3500' to land. The wind direction is from 232 deg.4

So, 232 divided by ten is 23. Runways that are long enough for your aircraft are 09, 15, 27, and 33. Of these, the one closest to 23 is 27. You would request and expect landing runway 27.5

This is a rough outline of the steps a math project would take to guess the landing runway. Most pilots have no trouble hearing the weather advisory, glancing at the Jepp chart, and just knowing which runway should be in use.

1. Often two digits are used, i.e. runway 9 is called 09.
2. If a tower controller is present, he will identify and grant access to the runway in use. Your project will calculate the most likely expected runway. With no controller, the pilot should co-ordinate with any present traffic before using your project result.
3. Notice that reciprocal runways occupy the same paving and perforce have the same length.
4. Your project must be told whether the reported wind direction is from or toward. When the reported wind direction is toward, as it might be from a non-navigational source such as a local news broadcast, you must calculate the reciprocal from direction.
5. If you had a plane that could stop in 1200' you would use runway 22.
• Reported wind direction is the direction the wind is blowing FROM. So you don't need to do the reciprocal. With wind direction of 282, you'd use runway 27. – Gerry Jan 21 '19 at 2:02
• After removing any runways that aren't long enough, wide enough or paved enough for the aircraft in question, of course, and whether there is a usable instrument approach if needed. And assuming no parallels or local factors (e.g. terrain, airspace) that can't be solved algorithmically – StephenS Jan 21 '19 at 2:03
• @Gerry: Thank you -- I missed the sentence "We fetch the wind direction (degrees) for that airport." - Whether the wind is announced is the direction TO or the direction FROM depends on the source, but that sentence does suggest a nautical or navigational source, which will be FROM. – A. I. Breveleri Jan 21 '19 at 2:12
• I did understand some things. But just to understand better, in my project there is no issue regarding runway length. Also, each runway has 2 numbers, 1 on each end. Do I use both numbers of each runway to calculate the difference between wind direction and runway direction. – Faizan Rahman Jan 21 '19 at 4:17
• Another questuon, – Faizan Rahman Jan 21 '19 at 4:17