Sunday, August 8, 2010

Airlines and Turbulence

I'm sorry to offer another airlines and turbulence posting and if the topic doesn't interest you, please skip right over this one.

I'm writing this because I sense a genuine problem and I would like to raise some awareness before something really serious occurs. Some background is in order.

Last July, flying on a non-stop between Phoenix and Wichita, the pilot told us before takeoff that "severe" turbulence was forecast and that the seat belt sign would be on most all of the flight. His comment surprised me because I looked at the weather before going to the airport and didn't see anything out of the ordinary.

We had quite a few bumps on takeoff (which is usual in summer in PHX) but, once we leveled off, the flight was extremely smooth. Nothing changed the next hour and a half: the flight was very smooth but the seat belt sign stayed on. Finally, after nearly two hours, the sign was turned off near Liberal, KS (getting close to Wichita) to "allow people to use the facilities" before we landed.  Flight summary: Near zero turbulence at cruise altitude but the seatbelt sign was on almost the entire flight.  Hmmm.

On a book-tour flight from Dallas to Kansas City May 10, the seat belt sign was on the entire flight even though there was no turbulence until we approached KC (where we had to circle because of a thunderstorm over the airport).  Double hmmm.

This morning, as we drove to the airport, I took the photo below of a single thunderstorm west of the airport. It was the only thunderstorm in the area and I didn't worry a bit because it was easily avoidable.

I looked at the radar when I got to the airport and it remained the only thunderstorm in the region. However, the storm was looking rather turbulent visually (meteorologists: note the mammatus clouds in the transition zone from the updraft to the anvil) in the photo below:

So, we take off and -- you guessed it -- we flew through the thunderstorm, even though it was easily avoidable! We had moderate turbulence for probably 30 seconds (the thunderstorm was not large) and then things smoothed out on the other side.

After we had been in the air for 30-40 minutes, I noticed it was odd that the seat belt sign was still on. At the 60 minute mark, smooth air but the seat belt sign still on. So, I took the photo below of the seat belt sign still on with the clear sky out the window (that part of the photo did not come out as well as I had hoped):

Why keep the seat belt sign on in completely smooth and clear air? To verify this was the case, you can see this weather satellite image showing the thunderstorm just north of the Wichita airport then clear skies from eastern Kansas until we got into the vicinity of Chicago.

What's going on?

This is especially perplexing after the injury-causing flight last month over Missouri when a jumbo jet flew through the top of a thunderstorm? Why are commercial airline pilots flying through thunderstorms but using unnecessary caution by keeping the seat belt sign on in clear air?

I have a couple of theories:  Pilots are not being adequately trained about what meteorology knows about turbulence today and they are not being trained in proper onboard radar scanning techniques.

The first theory got some support this afternoon when I had the opportunity to chat with pilots from two airlines about their turbulence training. Essentially, if those pilots are representative (and they may not be), pilot training with regard to turbulence is about the same as it was in the 1980's. It shouldn't be, we've learned a lot since then.

The second problem is more subtle. In order for our pilots to see the thunderstorm before we took off this morning, the pilots would have had to tilt the radar antenna up. (see diagram below)  And, in order to get a good view of the Missouri thunderstorm (see image at link above), the pilots would, as they approached the thunderstorm, have to tilted the antenna down.

So, today, when we flew through the thunderstorm and its turbulence, I speculate the pilots may have been surprised at the intensity of the turbulence because they didn't realize they were going to fly into a storm because the radar wasn't used properly (lower clouds could have obscured the storm from the pilots' view) so, to be "safe," they left the seat belt sign on. Because they were surprised by the thunderstorm, they didn't want to be surprised by turbulence again.

Why is all this important? The pilots I was chatting with commented "it is important for passengers to observe the seat belt sign." The flight attendants (especially from Chicago to D.C. today) emphasize this.

But, I fear, pilots are -- too often -- training their passengers not to observe the sign. Fly enough miles with the seat belt sign on but no turbulence and you're tempted to get up, sign or no sign.

So, I am hoping to raise a little awareness with this post. Pilots: Get aggressive working that onboard radar and take a look at some of the more recent literature about thunderstorms and turbulence. The old "20-mile" rule -- by itself -- doesn't cut it any more.


  1. A blog reader had problem posting a comment, so I am posting it for him:

    "As a licensed aircraft dispatcher(though not working as a dispatcher) imo for the most part you've hit the nail on the head with this one."

    While I'm glad I had this figured out, it tells me there is a problem the airlines need to get a handle on before something really serious occurs.


  2. Just come across your weather website..well what can I say...brilliant. So much information and fantastic comments above. I have bookmarked this site, and have emailed my weather fan friends. Keep up the good work!

    Weather Station Reviews

  3. Aspire,
    Thank you, glad you enjoy it!

  4. Mike,

    Good thoughts.

    In any accident will eventually boil down to "pilot error", so some of the time I think they'd rather be safe than sorry. Having been an aviation forecaster for a number of years, I quickly learned that areas of CAT are much, much smaller than one would expect. I remember making a quick forecast before taking an airline flight and verifying it en route.

    I see a couple of areas where great progress was made in meteorology and the education of users through the mid-90s and then stopped dead in their tracks.

    Again, good thoughts.

    Chris Orr CCM

  5. Thanks, Chris. I had exactly the same experience earlier this evening (August 13th) flying from IAD to BNA -- seat belt sign on virtually entire flight with no turbulence until our approach to BNA. For now, I've decided not to write it up because I don't want turbulence to dominate the blog.
    Best wishes,


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