Choosing the runway correctly is very important for a perfect departure and arrival. Sometimes this can be really confusing on how to choose the runway. To choose the runway, one should must learn how to decode a METAR. You can find it here
BENEFITS OF WINDS
Aircraft land and takeoff into the winds. Some of it’s benefits are -
- It gives the aircraft greater climb rate or steeper descend rate (as required).
- It allows the plane to stop as the headwinds act as breaks on the plane. This makes the brakes of the plane relax and avoids overheating of the brakes.
CHOOSING THE RUNWAY
If ATC is available, they would guide you to the suitable runway which is feasible considering traffic and weather.
Runway to be used can be determined with the help of heading of winds. You can use the simple formula :
| HEADING OF WINDS - 180° | = YOUR APPROACH HEADING
Now you can use the runway which suits to your approach heading and the airport.
APPROACH HEADING OF THE RUNWAY TO BE USED = | YOUR APPROACH HEADING ± 90° |
( | | → this sign indicates modulus )
For better understanding, refer to the example below.
EXAMPLE OF RUNWAY CHOOSING
Let us consider an example of VIDP runway 27/09. Look at the METAR reading below :
It shows that the winds are heading at 130° (magnetic) at 4 knots. So we can make a simple diagram out of it as shown below :
Now applying the formula above :
→ | HEADING OF WINDS - 180° | = YOUR APPROACH HEADING
→ |130° - 180°| = 50°
So 50° should be my final approach heading in order to convert the wind into headwinds. But, VIDP does not have runway 05.
→| 50° ± 90° | = 40° to 140°
The above calculation shows that I can have my final heading anywhere between 40° and 140°. Now at VIDP I am available with runway 09 which has final magnetic heading of 90°.
So we can land on runway 09 at VIDP with the given METAR.
There are some exceptions where you are allowed to land with tail wind. Some are :
ATC can use runway with tailwind in case of traffic. But if wind speeds exceed maximum allowed speeds, they will change the runway.
When crosswind component, including gusts, exceeds 15KT (28km/h), or the tailwind component, including gusts, exceed 5kt (9km/h), the pilot have to change the runway.