Dictionary Definition
headwind n : wind blowing opposite to the path of
a ship or aircraft
User Contributed Dictionary
English
Etymology
From head + wind.Antonyms
Translations
A wind that blows directly against the course of
an aircraft or ship
- Finnish: vastatuuli
- German: Gegenwind
- Swedish: motvind
Extensive Definition
A headwind is a wind that hits a vehicle in the
front. This reduces the vehicles' speed and increases the time to
reach a destination.
In sailing, it may make forward movement
difficult, and necessitate tacking into the wind.
In aeronautics, it is favourable in takeoffs and landings where aviators and Air
Traffic Controllers choose the side of the runway with the wind coming
against the aircraft.
Headwind Component
Pilots calculate the Headwind Component, Tailwind Component and Crosswind Component of any wind, if they do exist. Headwind and Tailwind are cosine functions of the wind while Crosswind Component is a sine function. Headwind and Tailwind do not occur together in normal conditions.Assume: A=Angle of the wind from the direction of
travel WS=The measured total wind speed CW=Crosswind
HW=Headwind
Then
CW=Sin(A)*WS HW=Cos(A)*WS
For example if the wind is at 24015 that means
the wind is currently from heading 240 degrees
with a speed of 15 Knots and
the aircraft is taking-off from runway 18; having heading of
180.
Crosswind = Sin(240-180)*15 ≈ 13 Headwind =
Cos(240-180)*15 ≈ 7.5
The aircraft is said to have 13 knots of
crosswind and 7.5 knots of headwind. Aircraft usually have maximum
headwind and crosswind components which they cannot exceed. If the
wind is at eighty degrees or above it is said to be full-cross. If
the wind exceeds 100 degrees it is common practice to takeoff and
land from the opposite side of the runway, it has a heading of 360
in the above mentioned example.