“When everything seems to be going against you, remember that the airplane takes off against the wind, not with it.”
These words of encouragement from Henry Ford are worth remembering at those times in life when everything seems to be going against you. They are also very true; aircraft need a headwind both to take off and land. Aircraft need less runway if they take off into a headwind and are able to come to a standstill quicker with the wind against them on landing. The direction of the wind even determines which runway is used! Airfields are obliged to offer a runway that provides the strongest headwind. But what happens when the wind blows from the “wrong” or an unfavourable direction. What is an “unfavourable wind” and how is it able to delay your flight?
Everyone has certain experience of “unfavourable winds”. For instance, when you happen to be behind someone at the wrong moment, in a headwind. Or, for the boys among us, those times when a breeze blows up as you are performing number one. An unfavourable wind in aviation, on the other hand, means a (strong) sidewind. Under these conditions an aircraft approaches landing with its nose in the wind and turns to face the runway at the last moment. Aircraft are not allowed to land if a sidewind across a runway is stronger than 20 knots (37 kmh, or wind force 5).
So, an unfavourable wind can lead to fewer runways being used and a build up of traffic on the other runways. Schiphol Airport handles 34 landings/hour on each runway and, consequently, doesn’t need all the runways open to be able to land all the aircraft. But if, due to an unfavourable wind, only one runway is open and it’s busy, aircraft sometimes have to wait in the air until it’s safe to land.
The good news is that the wind can be forecast pretty accurately. However, this can make a situation harder for passengers to comprehend; you hear in Rome, where there isn’t a breath of wind, that your flight has been delayed because of wind in Amsterdam. But hey, what’s a little delay? If you’re feeling really unlucky, just remember that the airplane takes off against the wind, not with it.”