In brief:
- Turbulence is measured by something called the Eddy Dissipation Rate (EDR)
- It’s a standard measure that’s used across the world
- EDR doesn’t directly translate to in-flight turbulence levels, because turbulence level depends on the size and weight of the plane
What is the Eddy Dissipation Rate?
If you’ve used a commercial turbulence forecast app like Turbuli, you’ll have seen mentions of 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 levels, and how are they classified?
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.
Why passengers don’t need to worry about EDR
The EDR, like many other flight acronyms, systems and processes like PIREPs, aren’t relevant to most passengers. Anxious flyers may seek to understand how turbulence is calculated to give them some control – but this is an illusion.
Instead of attempting to forecast turbulence through apps, or understand how our flights might be affected by jetstreams, it’s much better – and healthier – to accept that turbulence may occur and understand that it’s safe.
You can find lots of information about the causes of turbulence and why it’s not dangerous on our Fear of Flying section. If turbulence is a source of anxiety or stress, visit the Help Desk and download the Calm Flight Toolkit.
You can also check out the Fly Above Fear System for a 4-step way to reduce anxiety and increase confidence.
Please share this article with anyone who might benefit from it.
FAQs
EDR is an acronym that stands for Eddy Dissipation Rate. It’s the standard international measure of how energy dissipates in the atmosphere and can be used to grade turbulence.
If you’re a pilot, flight planner or aviation expert then definitely. (You’ll probably want to find a more comprehensive definition, too.) If you’re an anxious passenger, then understanding the EDR won’t really help you. In the end, you need to put your faith in the safety of commercial aviation.
Yes, you can use the EDR to estimate turbulence levels (as models like Turbuli do), but as we’ve explained, the turbulence you may experience will depend on several factors, including the size and weight of the aircraft. Pilots will typically use their experience to grade turbulence as they’re experts. (Passengers typically over-estimate the severity of turbulence.)
