{"id":24394,"date":"2024-02-05T08:14:33","date_gmt":"2024-02-05T13:14:33","guid":{"rendered":"https:\/\/ops.group\/blog\/?p=24394"},"modified":"2024-02-05T08:16:18","modified_gmt":"2024-02-05T13:16:18","slug":"who-is-eddie-and-what-does-he-have-to-do-with-turbulence","status":"publish","type":"post","link":"https:\/\/ops.group\/blog\/who-is-eddie-and-what-does-he-have-to-do-with-turbulence\/","title":{"rendered":"Who is Eddie? And what does he have to do with turbulence?"},"content":{"rendered":"

The other day, before another oceanic crossing, I settled in to brief myself on that afternoon\u2019s flight plan.<\/p>\n

As I scalded my mouth with a hastily purchased airport coffee and began to peruse the carefully collated collection of fuel burns and leg times, my eyes fell upon the dispatcher’s remarks. As I stared, the following note stared right back at me…<\/p>\n

\u201cSorry guys, unavoidable EDR 60 at TOC…\u201d<\/span><\/em><\/p>\n

Apology accepted. But what on earth is EDR 60?<\/strong><\/p>\n

With the weight of the braid on my shoulder, multiplied by a factor of my stupidity as a proficient but highly \u2018human\u2019 aviator, I realised I needed to call in the big guns – this was a job for Google.<\/p>\n

A powerful blankness ensued as I surveyed the answer… Eddy Dissipation Rate.<\/strong> The official metric of ICAO and World Met Organization turbulence reporting since I was in high school. Had I been living in a cave?<\/p>\n

This thing mattered, and so I needed to dig deeper.<\/p>\n

Here\u2019s what I found out:<\/p>\n

…it\u2019s an aircraft-independent meteorological field expressed in meters squared per second cubed…<\/em><\/p>\n

Not helpful. I read on…<\/p>\n

…the cube root of the dissipation rate of turbulent kinetic energy… <\/em><\/p>\n

I took another sip of coffee. I didn\u2019t have time for this.<\/p>\n

Sign-on was approaching, along with hundreds of passengers expecting me to protect them from this \u2018EDR 60′ with my big fancy license. All I knew was that it meant bumps.<\/strong> Clearly, I needed to get a better grasp on this.<\/p>\n

If you already know what EDR is, and could explain it to me on a napkin, there\u2019s no need to read on. If you\u2019re \u2018asking for a friend,\u2019 here is a crash course, written in human.<\/p>\n

The Simplest Answer<\/h4>\n

You don\u2019t need to cube anything. Except maybe the confidence you lost (like me) in not knowing what an EDR is. It’s pretty simple (ignoring the arithmetic of measuring it).<\/p>\n

The higher the number, the more intense clear air turbulence may be…if you encounter it.<\/strong>\u00a0 Anything over 50 may result in moderate to severe CAT.<\/strong><\/p>\n

But that interpretation also depends on the type of aircraft you are flying.<\/p>\n

So, there may be some nasty stuff around. But if you want to get your head around it, you’ll need to dig a little deeper.<\/p>\n

So, let\u2019s dig…<\/h4>\n

When we talk about turbulence, we refer to light, moderate, severe, and extreme.<\/strong> We attempt to categorise these with useful definitions like \u2018loss of control.\u2019<\/p>\n

The problem is that it is quite challenging to quantify the severity of CAT concerning different aircraft types \u2013 what\u2019s bad in a 152, may not be as bad in a Gulfstream.<\/strong> It varies from aeroplane to aeroplane, and forecasters don\u2019t know what equipment you operate.<\/p>\n

This is where EDR comes into it \u2013 it doesn’t cares about what aircraft you fly.<\/strong> It is just a measure of something.<\/p>\n

An eddy is simply the swirling of fluid. And air behaves like a fluid. A turbulent atmosphere will make these eddies disappear quicker. A calmer one will allow them to persist.<\/p>\n

So, if we know what is happening to these eddies, it can give us an indication of how \u2018churny\u2019 the atmosphere is, along with a healthy dose of mathematics, of course.<\/p>\n

Eddies dissipate quickly = a turbulent atmosphere.<\/strong><\/p>\n

An EDR is measured with a value of between 0 and 1. But seeing a value of 0.4 for instance, doesn\u2019t exactly leap off the page of your flight plan.<\/p>\n

So, we multiply it by a factor of 100 to make it easier to use.<\/p>\n

Cool, we\u2019re almost there…<\/p>\n

One size doesn\u2019t fit all<\/h4>\n

Once we have an EDR, we must know what to do with it.<\/p>\n

As mentioned, every aircraft is different and will respond differently to turbulence. This is where weight begins to matter.<\/strong><\/p>\n

An EDR of 20 might produce moderate turbulence for a King Air, but gently shake the champagne glasses of an A380 and nothing more.<\/p>\n

The clever folk at the National Center for Atmospheric Research, therefore did a study and came up with three weight classes to help you understand an EDR:<\/p>\n

\"\"<\/strong><\/p>\n

Where do I find this EDR?<\/h4>\n

Many non-airline folk don\u2019t have the luxury of a friendly dispatcher like I had.<\/p>\n

But you can quickly look it up. Better yet, it is as simple as paint by numbers (if you know what to do with the answer).<\/p>\n

It would help if you had GTG (graphical turbulence guidance) like the one below. And the colours change depending on how heavy your aeroplane is.<\/p>\n

\"\"<\/a>

The NOAA’s example of a GTG chart (graphical turbulence guidance).<\/p><\/div>\n

Better yet, the way EDRs are presented can be changed. For instance, cross-sections of a route can also give pilots a good indication of the smoothest levels.<\/p>\n

Check out the NOAA website here<\/strong><\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"

The other day, before another oceanic crossing, I settled in to brief myself on that…<\/p>\n","protected":false},"author":49,"featured_media":24484,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[2237,2236,2163],"class_list":{"0":"post-24394","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-briefings","8":"tag-cat","9":"tag-edr","10":"tag-turbulence"},"_links":{"self":[{"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/posts\/24394","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/users\/49"}],"replies":[{"embeddable":true,"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/comments?post=24394"}],"version-history":[{"count":27,"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/posts\/24394\/revisions"}],"predecessor-version":[{"id":24513,"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/posts\/24394\/revisions\/24513"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/media\/24484"}],"wp:attachment":[{"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/media?parent=24394"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/categories?post=24394"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/tags?post=24394"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}