Weather is a topic that nearly everyone talks about each day. I imagine that just about everyone would like to live and work in warm sunshine. Pilots would love to fly in continuous warm sunny weather. Hawaii comes to mind. Only problem is that even Hawaii suffers rain and storms.

Pilots have to learn how to handle different weather situations.

Flying at night should be mentioned here as well because flying at night involves flying with a reduced visibility. This really involves instrument flight. This is covered under the menu item "Instrument Flight".


Definition: one knot is one nautical mile per hour. This is the unit used for speed aboard airliners. One nautical mile is defined as one minute of arc of latitude. There are 60 minutes in one degree. Therefore the distance from the Equator to the North or South Pole would be: 90 (degrees) multiplied by 60, which equals 5,400 nautical miles. As a comparison with other units of measurement: 100 knots equals 115 miles per hour, equals 185 kilometres per hour.

There is a definite relationship between speed in knots and navigation. See "Navigation" option.

Wind: An aeroplane flies on airspeed, the only difference that wind makes is to affect groundspeed. In still air a B747 flying at 500 knots (airspeed) would cover 500 nautical miles in one hour. If this B747 had a tailwind of 100 knots its effective groundspeed would be 600 knots, that is, the plane would cover 600 nautical miles in an hour.

Conversely, if this B747 had a headwind of 50 knots its effective groundspeed would be 450 knots and travel 450 nautical miles in one hour.


On takeoff and landing pilots prefer to fly into wind because the groundspeed is less than the airspeed and hence the distance required on the runway is less. The only real problem that wind creates in this phase of flight is if the wind blows across the runway, that is; crosswind. Each aeroplane has a definite crosswind limit.

Typically for a B747 the crosswind limit is 30 knots. If the crosswind is stronger than this pilots are not authorised to land or takeoff. I should mention that this limit is reduced on wet runways and during poor visibility.

Rain or Snow
Rain and snow cause visibility problems and also can make the runway slippery. Visibility problems are covered under "Instrument Flight". Slippery or contaminated runways cause problems on both takeoff and landing. They can reduce the acceleration on takeoff and also make stopping difficult on landing. There are limits to which pilots can operate their planes in these conditions and there are performance penalties that must be taken into account before a plane lands or takes-off. For example, on landing the distance required to stop on a wet runway is 15% greater than that required on a dry runway.

Landing and take-off

When stopping a large plane such as B747 pilots have at their disposal: autobrakes, manual brakes, and reverse thrust.

Before take-off and landing the pilot checks the runway length available and applies an adjustment for a contaminated runway.

The pilot panel here shows the weather ahead.
The white triangle is the plane. Here I am 50 nm off to the right of track avoiding a monsoon on the East coast of India.
The plane is at 37,000 feet. Refer to instrument flight page for more information on various pilot panels.

The radar here is pointed down at five degrees. Normally we use one or two degrees. Place your mouse over the picture to see a 1-2 degree view.

You can see why I have chosen to deviate to give my passengers a smooth flight. The 1-2 degree view shows the clear path as we over- flew the lower weather displayed on the 5 degree view.

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