In brief
- Turbulence is graded on a scale, including light, moderate, severe and extreme turbulence
- Turbulence is measured using a scale called the Eddy Dissipation Rate (EDR)
- Turbulence is a safe and normal part of flying and planes are built to withstand levels of turbulence much higher than pilots and passengers are ever likely to experience
- Breathing exercises, grounding techniques and mindfulness can help to calm you during turbulence
Understanding turbulence levels
Turbulence is classified by the industry into four categories according to its severity. You’ll find descriptions of light turbulence, moderate turbulence, severe turbulence, and extreme turbulence.
Any mention of turbulence can scare nervous flyers, but the reality is that turbulence is safe, normal and should be expected on every flight.
You need to feel the bumps, not fear them.
Here, we’re going to explore the different levels of turbulence, provide a basic explanation of how pilots measure turbulence, and provide some resources that can help you to understand what causes turbulence and why it’s nothing to worry about.
How is turbulence classified?
In the world of aviation, there’s an agreed upon rating for turbulence with clear classifications.
As a fearful flyer, you’ve probably come across these classifications before: light, moderate, severe, and extreme turbulence.
Turbulence is complicated to describe. We all experience it in slightly different ways. (An experienced pilot may not even register light turbulence, but a fearful flyer might, for example.)
To help you understand what turbulence is, how it feels and what it means, we’re going to describe each type of turbulence in three ways:
- The science
- The passenger perspective
- The pilot’s perspective
Light turbulence
The science:
On the turbulence scale, light turbulence usually measures around EDR 0.1–0.2 (EDR, or eddy dissipation rate, is a standard way to quantify turbulence – more on this later).
When it’s in the air, the aircraft may experience small, rapid variations in airspeed (less than 15 knots), slight changes in altitude (tens of feet rather than hundreds), and minimal changes in attitude (pitch, roll, or yaw).
Passenger perspective:
It feels like a gentle ripple through the cabin. Your drink might wobble in its cup, but you can still read, chat, or type without much trouble.
Pilot perspective:
It’s a minor note in the day’s flying – noticeable enough to keep an eye on, but it rarely requires a change in altitude or course. Pilots may switch on the seatbelt sign as a precaution, especially if the turbulence is forecast to continue or increase in intensity.
Moderate turbulence
The science:
Moderate turbulence generally measures around EDR 0.2–0.4. Here, airspeed variations can be 15–25 knots, altitude can change by a few hundred feet, and there are more distinct shifts in aircraft attitude. The autopilot remains in control but may work harder to maintain stability.
Passenger perspective:
It’s more of a noticeable jostle. Drinks might spill, walking down the aisle becomes a challenge, and you’ll be grateful for that seatbelt.
Pilot perspective:
It’s a cue to slow the aircraft to turbulence penetration speed (a safe, recommended speed for comfort and airframe stress reduction). Communication with air traffic control may include requests to change altitude or route to find smoother air.
Severe turbulence
The science:
Severe turbulence typically measures EDR 0.4–0.6 or higher. Airspeed variations can exceed 25 knots, altitude changes can be several hundred feet in seconds, and there are abrupt, significant changes to pitch and roll. The autopilot may disengage, requiring manual control.
Passenger perspective:
This feels intense, like an unexpected rollercoaster drop combined with side-to-side sways. You’ll be firmly in your seat (and glad of it), and anything unsecured might shift or fall.
Pilot perspective:
The focus becomes managing the aircraft’s attitude and keeping it within safe limits. Pilots avoid making control inputs that could worsen structural loads, relying on training and quick assessment to get the aircraft back into smoother conditions as soon as possible.
Extreme turbulence
The science:
Extreme turbulence, with EDR above 0.6 is rare. It can cause violent changes in airspeed and altitude, potentially exceeding the structural limits of the aircraft if prolonged (though aircraft are designed with large safety margins). The forces involved can momentarily make control of the aircraft difficult.
Passenger perspective:
It’s a short but overwhelming experience. You might feel pressed into your seat, then briefly lifted, with strong sideways jolts. Thankfully, commercial flights almost never encounter this level of turbulence.
Pilot perspective:
Avoidance is the goal. Extreme turbulence is nearly always spotted on radar, through weather reports, or from other pilots’ reports. If encountered unexpectedly, the priority is to maintain structural safety, communicate with ATC, and exit the affected area as quickly as possible.
Turbulence v chop
If you’re a fearful flyer who has read pilot reports or searched online for turbulence explanations before, you may have come across the term chop.
Chop and turbulence are often used interchangeably, but they mean slightly different things.
For pilots, chop can cause bumps or jolts in the cabin with little to no impact on altitude (height) or attitude (how the aircraft behaves in the air). It’s like driving over a slightly bumpy road.
Turbulence does cause changes in aircraft altitude and the way the plane behaves.
Pilots can report chop as only light or moderate, but turbulence can be categorised as light, moderate, severe or extreme.
How is turbulence measured?
Turbulence is measured using something called the Eddy Dissipation Rate. If you’ve used a commercial turbulence forecast like Turbuli, you’ll have seen mentions of the EDR.
The Eddy Dissipation Rate is a standard measure that’s used in aviation to quantify the intensity of turbulence.
It’s a near-universally applied measure of turbulence that’s used by the International Civil Aviation Organization (ICAO) and the World Meteorological Organization (WMO).
The EDR effectively measures the rate that energy dissipates in the atmosphere. EDR values range from 0 to 1 and are a useful way to measure turbulence, but it’s not as simple as it seems.
A light aircraft may experience moderate turbulence at an EDR of 0.15, for example, but this may barely register in a heavier aircraft like the monster A380.
Turbulence forecasting tools apply a blanket EDR rating which doesn’t take into account the size of plane you’re flying in. Yet another reason why they’re not useful as an indicator of in-flight conditions.
What are the turbulence classifications?
EDR is used by official bodies like the ICAO to classify turbulence into the standard categories:
- Light turbulence
- Moderate turbulence
- Severe turbulence
- Extreme turbulence
Turbuli uses a relatively basic way to measure turbulence levels. These crude cut-off points it uses mean that the predictions for turbulence are flawed and may not reflect how your plane will experience turbulence in the sky.
This matters because many fearful flyers can find anxiety spikes if turbulence is forecast, but this may not ever occur during flight.
How do pilots measure turbulence?
Some planes have systems that can measure Eddy Dissipation Rate (EDR). Pilots can calculate it from onboard measurements like vertical acceleration or vertical winds.
In reality, most pilots have flown thousands of hours and experienced more turbulence in a year than most flyers will in a lifetime. They use this knowledge to report turbulence in PIREPS. In one sense, it’s subjective, but years of experience mean other pilots can trust the judgment.
On real-time maps you can see pilot reports of turbulence. These are for pilots to use, not passengers.
Instead, watch this great video from pilot Stuart Walker where he explains what turbulence is and why you shouldn’t be worried about it.
Feel the bumps, don’t fear them
YouTube is full of videos created by pilots, engineers and aviation experts that can help you. The problem with the algorithm is that as soon as you start to search for positive turbulence videos, you get shown videos of scary flights, which can heighten anxiety, not help.
While you may experience moderate and even severe turbulence on a flight, it’s rare this will happen. Watching these videos can – and will – heighten your anxiety, so avoid them.
Instead, focus on the things you can control. Like being calm, relaxed and in the moment. If you need some help, download our free Calm Flight Toolkit or visit the Help Desk for resources.
Please share this article with anyone who might benefit from it.
FAQs
Pilots will have developed an intuitive feel for turbulence and can grade it. There’s a tendency for passengers to over-estimate the severity of turbulence. In the end, it doesn’t really matter. Planes can – and will – safely fly through turbulence. It might be uncomfortable, but it’s not unsafe.
Yes. it’s nothing to do with the design of the plane, but the size. It will take more energy to move a large plane than a small one. If you both planes (an A320 and an A380, for example) flew through the same rough air, it’s likely that turbulence would be felt slightly more acutely on the smaller A320. That’s because the A380 is almost twice as long and with twice the wingspan. Both planes would remain safe, of course.
Some forms of turbulence, like those caused by storm clouds, can be seen and avoided. However, as its name suggest, clear air turbulence is impossible to spot. That doesn’t mean that pilots are on their own. they have access to increasingly accurate forecasts and can get real-time information from other pilots to plot the smoothest course. Sit back and relax, you’re in great hands.