What is air turbulence?
Air turbulence refers to sudden, irregular motions of air that can occur at any time during flight. It is caused by changes in air movement that disrupt the smooth flow of air around an aircraft. Turbulence can range from slight bumpiness to violent jolts that can toss passengers and crew around an aircraft cabin. Moderate or severe turbulence poses a safety risk and can cause injuries if passengers and crew are not seated with their seatbelts fastened when it occurs.
What causes air turbulence?
There are several different causes of air turbulence:
Thermal turbulence
This occurs when air is unstable due to differences in temperature in the atmosphere. For example, turbulence can form when a warm air mass meets a cold air mass at different altitudes. The boundary between these two air masses can create eddies and disruption in airflow.
Clear air turbulence
This refers to turbulence that occurs in clear skies with no visual indicators like clouds. It is caused by strong jet streams high up in the atmosphere that generate turbulent eddies at their boundaries. Clear air turbulence can be difficult for pilots to predict or detect ahead of time since there are no cloud formations to signal areas of turbulence.
Mountain wave turbulence
This affects aircraft flying over or near mountains. As winds blow across mountaintops, they generate waves in the atmosphere on the downwind side. These mountain waves cause air to rise and sink in a oscillating pattern, creating turbulent conditions for aircraft passing through these areas.
Wake turbulence
This is caused by wingtip vortices generated by other aircraft flying ahead. All aircraft generate wake turbulence behind them, but it dissipates quickly at low altitudes. At cruise altitudes, wake vortices can persist for several minutes and create turbulence for following aircraft.
Thunderstorms
These generate severe turbulence near cumulonimbus clouds due to strong updrafts and downdrafts inside the storm cells. Turbulence from thunderstorms can extend for miles outside the clouds themselves. Pilots avoid thunderstorms by at least 20 miles whenever possible.
How does turbulence affect aircraft?
Turbulence poses several risks to aircraft:
- It can cause violent shaking and jolting motions that can injure passengers and crew if they are not seated with seatbelts fastened.
- In extreme cases, it can lead to structural damage or even breakup of the aircraft due to excessive stresses on the airframe.
- It can cause sudden altitude changes or attitude changes as the aircraft is buffeted up and down or side to side by turbulent eddies.
- This loss of control requires immediate pilot input to stabilize the aircraft.
- For smaller general aviation aircraft, severe turbulence can potentially lead to loss of control if the pilot does not respond appropriately.
Modern commercial airliners are engineered to withstand very heavy turbulence. However, turbulence still directly results in passenger and flight attendant injuries every year, mainly due to people being tossed about the cabin or galley areas. Severe turbulence has directly led to a few aviation accidents over the decades when aircraft stressed beyond design limits or pilots lost control.
Are turbulence events increasing?
There are disagreements within the aviation industry regarding whether the frequency and severity of turbulence events are increasing over time. Some major factors contribute to the perception that air turbulence is getting worse:
Improved reporting
Pilots today have multiple methods to report turbulence events and their severity or location. Detailed turbulence reporting helps other pilots avoid these areas, but also creates large databases to analyze patterns and frequency. More reporting tools mean more reported events, which can give the impression of increased frequency versus the past.
Route changes
Air traffic patterns today concentrate air traffic along organized routes and at cruising altitudes of 30,000 to 40,000 feet. Turbulence often occurs more frequently at these altitudes. Rerouting around severe weather also funnels traffic into smaller air corridors. Higher density of flights in these areas again increases likelihood of turbulence encounters for individual aircraft.
Changing climate
Climate change models project increased storm intensity and frequency in some areas in coming decades. Since thunderstorms generate some of the most severe turbulence events, increasing future storm activity could mean more turbulent skies globally. More research is needed to fully understand these long-term effects.
Are there any ways to alleviate turbulence?
Aircraft and air traffic technologies today provide several methods to help pilots detect areas of turbulence before encountering them:
Weather radar
Onboard weather radar allows pilots to visually identify convective activity associated with turbulence like thunderstorms. This allows rerouting early to avoid these areas.
Turbulence reports
Pilots relay turbulence encounters to air traffic control, which then alerts other pilots in the area. Forecasts are also issued identifying regions of possible turbulence.
Turbulence prediction models
Advanced computer models forecast turbulence using weather data and atmospheric wind patterns. In-flight data links provide real-time updates into these models from other aircraft.
Predictive algorithms
New algorithms utilize onboard sensors and live weather data to identify conditions likely to create turbulence along the flight route within the next 10-20 minutes. Early-warning allows pilots to request altitude changes to avoid these areas.
Conclusion
In summary, turbulence encounters will always be an unavoidable aspect of aviation as aircraft traverse diverse weather conditions and terrain variations. While turbulence may not be increasing from an objective standpoint, improvements in reporting and changing traffic patterns mean pilots today experience turbulence events more frequently than in the past. This creates an impression that turbulence is getting worse over time. New onboard prediction technologies provide better situational awareness for pilots to proactively avoid turbulent conditions whenever possible. Continued research and data analysis will provide a clearer picture of long-term trends in aviation turbulence and its underlying factors. Aircraft design advancements and refined air traffic management procedures will also help make turbulence encounters safer and allow for a smoother ride through the world’s often unruly skies.
| Cause of Turbulence | Description |
|---|---|
| Thermal Turbulence | Caused by air instability between warm and cold air masses at different altitudes |
| Clear Air Turbulence | Caused by strong jet streams generating eddies at their boundaries |
| Mountain Wave Turbulence | Winds blowing over mountains create oscillating waves and turbulence |
| Wake Turbulence | Generated by wingtip vortices from aircraft flying ahead in same airspace |
| Thunderstorm Turbulence | Powerful updrafts and downdrafts create turbulence around cumulonimbus clouds |
| Turbulence Impact | Description |
|---|---|
| Passenger injury | Being tossed around cabin can cause injuries if seatbelts not fastened |
| Structural damage | In extreme cases, can damage aircraft structure from excessive stresses |
| Attitude changes | Aircraft is buffeted up/down/sideways by turbulence |
| Altitude changes | Sudden drops or climbs in altitude |
| Loss of control | Pilot struggles to stabilize aircraft |
| Turbulence Mitigation | Description |
|---|---|
| Weather radar | Avoids thunderstorms and other turbulent convective activity |
| Pilot reporting | Pilots relay turbulence events to alert other aircraft |
| Turbulence forecasting | Computer models forecast areas of potential turbulence |
| Predictive algorithms | Onboard sensors identify turbulence 10-20 minutes ahead |