Ever wonder how jet streams affect airplanes? There are over 100,000 flights globally on any given day. While some of these flights involve short distances, others span more than 2,500 miles. For long-haul flights such as these, pilots will often take advantage of jet streams.
An Introduction to Jet Streams
Jet streams are narrow bands of fast-moving wind. They are often compared to rivers. While rivers carry water, jet streams carry air.
Most jet streams occur in the upper atmosphere — typically at an altitude of 20,000 to 40,000 feet. They form when warm air meets cool air. Air temperature differentials create a pressure gradient. The warm air (high pressure) will migrate to the cool air (low pressure), resulting in a jet stream.
Flight Times
Jet streams can affect flight times. Pilots will often intentionally fly in the same direction as a given jet stream to benefit from a tailwind. The jet stream will essentially push the airplane in the same direction in which it flows.
Due to their fast-moving speed — 100 to 300 mph — jet streams can shorten flight times for airplanes. Flights from North America to Europe, for instance, can arrive a half-hour to a full hour earlier by taking advantage of a jet stream.
Fuel Consumption
Another way that jet streams affect aviation is fuel consumption. By aligning flight paths with jet streams, airlines can lower their fuel consumption. Jet streams help to move airplanes through the air, meaning they don’t require as much engine-produced thrust to achieve the same speed or cover the same distance. The end result is lower fuel consumption.
Altitude
Jet streams can affect the altitude at which airplanes fly. As previously mentioned, most jet streams form at 20,000 to 40,000 feet. Pilots will often ascend to this altitude so that they can take advantage of a given jet stream.
Airline Costs
Airlines can save money by taking advantage of jet streams. Fuel, of course, is one of the largest expenses in commercial aviation. Statistics show it accounts for 15% to 20% of a typical airline’s operating expenses. By flying in the same direction of jet streams, airlines can save money on fuel.
Tubulence
While jet streams can help by moving airplanes through the air, they can also create turbulence. The outer edges of jet streams are particularly turbulent. They experience rapid changes in both wind speed and direction.
Pilots won’t completely avoid jet streams due to the potential for turbulence. Rather, they typically avoid the roughest parts of jet streams, such as the outer edges.