10 Surprising Facts about Turbulence

Fact: Turbulence is the leading cause of nonfatal aviation accidents every year. From 1980 through 2008, NTSB (National Transportation Safety Board) reported at least 298 serious injuries due to turbulence. Of those 298, 184 involved flight attendants and 114 involved passengers, with three of those suffering fatal injuries. After further investigation, it was determined that two of the three who died weren’t wearing their seat belts when the seat belt sign was illuminated.

What it means for you: Pilots always wear their seat belts. Whenever we get up to use the lavatory, we’re not considered to be back in our seat until our seat belt is securely fastened. It’s always a good idea to wear your seat belt, even when the seat belt sign is turned off.

Fact: Geographically, the United States has many natural phenomena that cause turbulence. A convergence of jet streams, mountain wave over the Rocky Mountains and a high incidence of convective activity over the entire contiguous United States creates an environment of atmospheric instability. While not always active, turbulence has a continual presence in North America, and turbulent conditions are always possible.

What it means for you: Pilots have access to the latest meteorological data as to the location and severity of areas of turbulence, and flight paths are planned to avoid such areas.

Fact: The convergence of air at the jet stream creates conditions of turbulence. To classify as a jet stream, winds must be greater than 50 knots. Winds are generally stronger (mid-latitude) during the winter months than in the summer (lower-latitude winds). Jet aircraft are often routed in or near the jet stream when flying west to east to take advantage of tailwinds. Conversely, the jet stream will be avoided when flying from east to west.

What it means for you: Our flight plans include graphic depictions of jet streams with our route of flight overlaying their location. If the two overlap, we’ll warn flight attendants and passengers of upcoming areas of turbulence.

Fact: Mountain wave—oscillations of air, as it blows over a mountain range—can cause clear-air turbulence at heights of up to 50,000 feet and can extend as far as 100 miles downwind from the mountains. If your flight path crosses the Rocky Mountains, expect to have turbulence or, at a minimum, mountain wave.

What it means for you: Pilots will rely on information passed from other pilots flying near mountains. PIREPs (Pilot Reports) give us ample warning of turbulent air.

Fact: The first step a pilot will take when coming across moderate turbulence is to slow the aircraft to turbulence penetration speed.

What it means for you: Think about riding in a boat at high speed when hitting rough water. The way a boat reacts to waves at high speed is much like that of an aircraft running into turbulence. While it is extremely rare to damage an aircraft during a turbulence encounter, it is a possibility. The slower speed not only reduces the chance of damage, but provides the passengers with a smoother ride.

Fact: In the late ’70s, Boeing engineers adopted damage tolerance principles to foster contemporary engineering methods to determine airframe inspection thresholds and intervals. All aircraft manufacturers now use these techniques when designing new aircraft.

What it means for you: These principles give mechanics an idea of how well structures sustain loads in the presence of fatigue, corrosion or accidental damage and maintain structural integrity until repairs are made. These techniques have increased the service life of aircraft and reduced catastrophic failures to near zero. Outcome: The aircraft you’re riding in is built like a tank, and can easily take any type of turbulence you’re likely to run into.

Fact: Roughly 40 percent of all turbulence-related accidents are caused by clear-air turbulence, which can’t be detected by conventional aircraft radar systems. However, cutting-edge technology is changing that.

What it means for you: LIDAR (Light Detection And Ranging), usually housed under the aircraft’s nose, combines radar and lasers to detect the speed of moving dust particles in the atmosphere, reflecting both light and radar energy back to the aircraft, which gives pilots an early warning of areas of clear-air turbulence. Even if it can see areas of turbulence only from six to 10 miles ahead, that 45-second warning is enough time to get flight attendants and passengers seated and belted in.

Fact: Satellites and advanced meteorology technologies have given pilots extremely accurate forecasts of areas of expected turbulence. PIREPs are always included in preflight plans and give pilots the latest reports of turbulence from airborne aircraft.

What it means for you: We are continually assessing flight conditions, making altitude and course corrections to give you (and us) the smoothest and most comfortable ride possible. If you’re comfortable, we’re comfortable.

Fact: Jet aircraft typically fly higher than most convective activity when possible. Generally, the higher an aircraft flies the smoother its ride. An exception to this occurs when flying near or through the tropopause. The tropopause is a thin layer separating the lower atmosphere from the stratosphere and is where most weather phenomena occur. The tropopause is lower at the poles and higher at the equator. Two-thirds of all turbulence-related accidents happen above 30,000 feet.

What it means for you: When meteorologists and dispatchers plan a flight, they’ll take into account the area where the flight passes through the tropopause and issue a turbulence warning to pilots.

Fact: Wake turbulence was not generally regarded as a flight hazard until the late ‘60s. A heavy aircraft with a large wing span will create the largest wake hazard in a clean (landing gear and flaps up) configuration at slow speeds. The greatest danger occurs when following a larger aircraft on final approach too closely.

What it means for you: Pilots and controllers are well aware of the hazardous effects of wake turbulence. Pilots are continually trained to recognize the signs of an impending upset and practice extensively in simulators. We know that the best way to deal with wake turbulence is to avoid it.