Short
Turbulence is a normal movement of air masses, as natural as waves on water, and not a sign of malfunction. The main causes are the collision of warm and cold fronts, air flow over mountain ranges, and the boundaries of jet streams, which generate clear-air turbulence—unseen by the eye or radar. Aircraft are designed to withstand loads many times greater than those caused by turbulence.
Turbulence is air movement that usually cannot be seen and often occurs unexpectedly. Per the FAA, it can be created by many conditions: atmospheric pressure, jet streams, air around mountains, cold or warm fronts and thunderstorms — and even under a clear sky.
What causes turbulence
Physically, turbulence is the irregular motion of disturbed air through which an aircraft flies. Per SKYbrary, its origin may be thermal or mechanical, and it occurs both within and clear of cloud.
Thermal turbulence comes from rising currents of heated air; mechanical turbulence from obstacles in the flow: mountains, hills, buildings. A separate source is wind shear — an abrupt change in wind speed or direction. The severity of turbulence depends on how quickly the speed or direction of the flow changes.
Clear air turbulence
The trickiest kind is clear air turbulence (CAT), which occurs without clouds and is invisible to the pilot. The FAA defines it as sudden severe turbulence in cloudless regions causing violent buffeting of the aircraft. It usually occurs at high altitude, most often above 15,000 feet, near jet streams.
With no visual cues, CAT is hard to predict. Pilots rely on forecasts, weather models and reports from other aircraft (PIREPs), and may request an altitude change to avoid the area.
Is turbulence dangerous
Modern aircraft are built to withstand turbulence with a large margin — the structure is not at risk in routine encounters. The main risk is not to the aircraft but to people: unsecured passengers and objects can be thrown about in a sudden jolt.
So the main recommendation of every aviation authority is to keep your seatbelt fastened whenever seated, even with the sign off. Most turbulence injuries are to unbelted passengers. Serious injuries are rare, and fatalities extremely rare.
Intensity categories
Turbulence is classified by intensity — from light to extreme. In light turbulence passengers feel slight jolts and seatbelts tighten a little. In moderate turbulence the jolts are more noticeable and unsecured objects may shift. In severe turbulence there are abrupt changes of altitude and attitude, passengers are pressed against their belts, and cabin service is stopped.
Extreme turbulence, where the aircraft is hard to control, is very rare and usually linked to thunderstorms the crew tries to avoid. Importantly, even severe turbulence does not threaten the structure of a modern aircraft — it is built with a large safety margin; the risk is to people, not the machine.
Mechanical and thermal turbulence
Mechanical turbulence arises when the flow meets an obstacle — mountains, hills, buildings — and breaks into eddies. Flights near mountain ridges are especially prone to it: air crossing a ridge forms updrafts and downdrafts. So near mountains the crew allows a margin and reduces speed.
Thermal turbulence is linked to heating: sun-warmed air rises, creating updrafts, especially over land on a hot day. Separately there is thunderstorm turbulence — the most intense, linked to cumulonimbus clouds; it shows on radar and is avoided in advance.
How aircraft handle turbulence
Modern aircraft carry systems that help detect and avoid turbulence: weather radar shows storm areas, while forecasting algorithms and reports from other aircraft (PIREPs) help plan the route. When turbulence is expected, the crew reduces speed to the turbulence penetration speed to lower structural loads.
Crew experience and training remain key: pilots can request an altitude change or route deviation from ATC for smoother air. All this makes encountering turbulence a manageable, routine event rather than an emergency.
Turbulence and fear of flying
Turbulence is one of the main causes of fear of flying, though statistically it is almost harmless to a passenger's health with a fastened seatbelt. The shaking feels stronger than it is: the brain reads unfamiliar accelerations as a threat, even when the aircraft is fully in control.
Understanding the phenomenon and trusting the crew and the technology helps. It is worth remembering: the aircraft is built to withstand loads many times greater than turbulence creates, and the shaking itself is discomfort, not a sign of danger. A fastened seatbelt removes almost all the real risk.
Is turbulence increasing
Research points to rising clear air turbulence due to climate change: warming strengthens wind shear in the jet streams. Per figures cited by the World Economic Forum, between 1979 and 2020 the frequency of severe clear air turbulence over the US and North Atlantic rose by 55%.
It is important to keep the scale in mind: severe turbulence affects only a fraction of a percent of flights. The increase means the seatbelt sign will be on more often, not that flying is becoming unsafe.
How the crew responds
When turbulence is expected, pilots switch on the seatbelt sign, inform crew and passengers, and if needed reduce speed to the turbulence penetration speed to lower structural loads. Thunderstorm turbulence is visible on weather radar and avoided in advance.
The crew may request a climb, descent or route deviation from ATC for smoother air. Cabin service is suspended in severe turbulence — a matter of safety.
When turbulence is more likely
Turbulence is not random: there are conditions that make it more likely. Flights over mountain ridges, near jet streams, through thunderstorm areas and atmospheric fronts, and over land on a hot day bring more shaking. Morning and evening hours over warmed ground, and crossings between air masses, are typical zones of increased bumpiness.
The crew knows these patterns and plans the route with them in mind, while forecasts and reports from other aircraft allow the altitude to be adjusted in advance. So an experienced passenger can roughly anticipate which parts of a flight may be bumpy — for example, crossing mountains or entering a weather area.
What a passenger should do
The rules for a passenger are simple and effective. The main one is to keep your seatbelt fastened whenever seated, even with the sign off: most turbulence injuries are to unbelted passengers. It is worth clearing heavy items off tray tables and making sure overhead baggage is secure.
When shaking starts — stay calm, return to your seat and fasten up, follow the crew's instructions. Turbulence is a routine part of flying that pilots and cabin crew are fully prepared for. Panic does not help, and simply following the rules removes almost all the real risk.
Turbulence in numbers
It helps to grasp the scale in numbers. Severe turbulence affects only a fraction of a percent of all flights, and serious injuries from it are rare — even though tens of thousands of flights are in the sky every day. Nonetheless, turbulence remains a notable cause of injury precisely because it catches the unbelted off guard.
Industry bodies estimate the economic cost of turbulence to global aviation at significant sums each year — mostly injuries and related costs, not damage to aircraft. This again underlines that the main risk factor is passenger behaviour, not the aircraft itself.
How turbulence affects the flight
Beyond the sensation in the cabin, turbulence affects the organisation of the flight itself. To avoid bumpy areas, the crew may deviate from the shortest route or change altitude, which increases flight time and fuel burn. Storm areas are circled, sometimes with a significant detour.
For airlines and operators these are tangible costs, and for the passenger sometimes a slightly longer flight for smoother air. In business aviation flexibility is greater: an aircraft can often pick the altitude and route for the specific weather, avoiding some areas a scheduled flight with a fixed timetable cannot.
Climate and forecasting
Turbulence forecasting is an actively developing field. Thunderstorm and mechanical turbulence can largely be predicted and avoided, but clear air turbulence remains hard to detect: it has no visual cues and instruments do not see it directly. So researchers are working on new methods to spot it early.
Climate change adds a challenge: warming strengthens wind shear in the jet streams, which, per research, leads to more clear air turbulence on busy routes. This does not make flying unsafe, but it means forecasting and route planning will play an ever greater role.
Turbulence and business aviation
The same principles apply in business aviation, with more flexibility: an aircraft can often choose the altitude and route for the specific weather, and the short legs and high cruise altitudes of business jets allow some areas to be avoided. Weather-aware route planning is part of flight preparation.
JetHunter accounts for weather factors when arranging a charter — from aircraft choice to route coordination — and understanding the nature of turbulence helps a passenger treat it calmly and correctly: a fastened seatbelt solves almost everything.
«Turbulence is a danger to the unbelted, not to the aircraft. In 14 years I have never seen an aircraft harmed by it — but I have seen what an unfastened seatbelt costs.»
— Alexey Mordvintsev, CEO of JetHunter
Author: Alexey Mordvintsev, CEO of JetHunter, President of the Association of Professionals of Executive Aviation Industry (APIDA). Over 14 years in the industry.
