If they know the flight will be choppy, why don't they find another route?

Factual Questions
21

To BwanaBob and all the other people who hate turbulence (does anyone actually like it?):

The “500-foot drop” is extremely rare. So rare that if it happens it usually makes the news in whatever country the airline flies to. I can’t say that it’s impossible…in aviation almost nothing is.

That being said, if you could come up front with me during turbulence and watch the altimeter, you’d see that we are moving no more than 10 or 20 feet up or down. It’s so little that the altimeter barely moves - just a little flicker up or down. Nothing to worry about at all.

Now about that “big drop” that can happen to an airplane but not to a car. In 14 years of flying I’ve hit severe turbulence exactly once. It was caused by a thunderstorm off the coast of Florida. Everyone was wearing their seatbelt, and no one was injured. The airplane itself was fine - no worries at all. You can do more damage to your car by hitting a pothole at 60mph than was done to our airplane. Both events are scary and nerve-wracking, but neither was life-threatening.

The bottom line is: if it wasn’t safe, I wouldn’t be doing it for a living. I FULLY expect to be around to collect my pension when I turn 60. :cool:

Hope this helps!

22

Many thanks pilot141,

This is helpful to me. Shocked to find out some of those bumps are only a
+/- 10-20 ft. If you would have said 100 I wouldn’t have batted at eye.

I guess the real heavy duty crap happens with thunderstorms (as you’ve mentioned). I was in a nasty squall landing at Orlando at dusk. We were about 5 minutes from landing when I saw a lightning flash in a cloud to my left and all of a sudden we were in a similar cloud and I’m certain I saw flashes outside.

We rose and fell like we were a roller-coaster (which incidentally I really hate too),
people were moaning/oohing and aaahing; the woman next to me opened her pocketbook and pulled out a pocket bible. I was freaking.

After we landed, when we exited the plane, it was the first time I saw a pilot “sweaty” and looking like he had a bad day.

23

Hate to say it, but I think it’s way more likely that your pension won’t be around when you hit 60 than the reverse. :frowning:

24

igloorex I fear that you may be right. Luckily I’ve got a long time before I hit retirement, so I’m planning financially for the pension NOT to be there. If it is, then it’ll be a bonus.

25

I think part of the problem is that you have people who are already anxious riding in a tube they can’t see out of very well, with zero control over the situation. Even without turbulence, this will tend to provoke anxiety. So they’re already nervous, which will just magnify the effects of any little bump.

On top of that, most vehicles folks ride in don’t move like an airplane in turbulence. Your car certainly doesn’t. Boats are the only comparable things I’ve found, and plenty of folks don’t like those, either. So the motion itself is alien to the average person. Infrequent fliers don’t know what’s either normal or safe. To some, this translates as everything being abnormal and possibly unsafe. Even when it isn’t.

On the other hand, some folks aren’t bothered - last time I flew back from Florida on an airliner we were weaving between thunderstorms and riding the bumps. Had a bunch of kids with their hands in the air squealing “wheeeeee!” like they were on a roller coaster.

Since I fly small planes that are tossed around a lot more in the air, airliners now seem pretty smooth to me. I find the average ride in a big jet significantly smoother than what I experience on my commuter train every work day. I’ll be sitting there calmly reading a book or looking out the window and the person next to me is sweating bullets and going “meep!” every other minute.

If you’re concerned, keep your seatbelt on as much as possible. It will keep you in your seat, obviously - it’s the folks walking up and down the aisles or in the lav who get hurt during the big bumps. Odds are, though, that you will never experience a really big drop.

26

As Pilot141 said, the gross disturbance of altitude in turbulence is 10-20 feet at most. But that’s NOT the amplitude of an individual bump.

When you’re bouncing along in typical uncomfortable “chop”, you’re bumping up and down a few inches each time. Over the course of 30 seconds or so (i.e. 4 miles forward progress and 40-50 individual bumps), the overall effect will move the airplane up or down 10-20 feet.

The slope of a 20 foot change in 4 miles is imperceptible.

You can get a worse ride on a dirt road at 40 mph, and you know the car’s only moving a few inches vertically.

Think about it. If you have a book or a soda sitting on your tray table and the table suddenly dropped 10 feet, wouldn’t the item end up bouncing off the ceiling as the ceiling came down to where the floor used to be?

If you bounced upwards, when the upward motion stopped wouldn’t the item tend to keep going, at least a little (Newton’s laws and all that?) The fact it moves only a smidgen, vibrating relative to your tray table, ought to give you a clue about the magnitude of the motions and forces involved.

The idea of 500 foot “drops” or “air pockets” is crazy. Can severe turbulence cause a 500 foot change in altitude? Yes. But spread over several seconds and a mile of distance. We’re not talking “fall off a cliff” here, we’re talking “slide down a shallow hill.”

The atmosphere does contain turbulence able to destroy an airplane. It lives inside large thunderstorms and tornadoes and such. That’s the reason thunderstorms create such havoc on the schedule when they fill the sky near an airport or along or across a major traffic route. They’re dangerous, so we give them a wide berth. Avoiding that is deadly serious business.

But the typical bumpiness enroute, or passing through rain or overcast during climb or descent is a totally different animal.

Psychologically, being a passenger is rough. You’re packed in so your personal space is massively violated and you’re helpless and you’re trapped in a situation you defeintely don’t control and mostly don’t understand. All those things are recipes for an emotional reaction ranging from mild discomfort to raging panic. That’s human nature and it’s a good thing in most situations. But it also leads to unneccesary, and unhelpful, anxiety in these situations.

Relax. I know that’s unnatural, but try your best.
As to fuel consumption versus altitude, consider this analogy: Go to the beach. Wade out into the water until it’s hip deep. Now start jogging parrellel to the shore. Pretty hard huh?. Move shorewards until the water’s knee deep. Jogging’s a lot easier. Move shorewards until the water’s ankle deep. Jogging’s almost the same as on dry land.

We cruise at a an altitude where the atmosphere is about 1/3rd the normal density or “thickness”. By climbing 2/3rd of the way out the top, we effectively do the same thing as the jogger going from hip deep to ankle deep. Major improvement in fuel consumption.

27

LSLGuy’s comments, as well as Pilot141’s and others, are most helpful. I still don’t understand why this turbulence exists (I assume that it’s a matter of up, down, and side winds up there) but I’m glad to be better informed as to why it’s so hard to avoid. It will help if I have to take another one of those flights where, instead of kids going “whooooeeee,” there were adults screaming, and when we landed, there was applause.

And, by the way, LSLGuy’s sig line is so true. I’d put it this way: The end of civilization came when we stopped living in any particular geographic area, and started living in a particular market.

28

I don’t care for the choppy ride like everyone else, however when flying through turbulence I often repeat to myself “Commercial planes don’t go down because of turbulence. This is a normal occurance. Planes crash because of malfunctions in the plane, not because of bad weather.”
Am I correct in making these assumptions? Have any commercial planes crashed because of really bad turbulance??

29

Delta Flight 191 crashed in Dallas while on landing approach because of wind shear, a form of turbulence caused by thunderstorms.

http://www.airdisaster.com/special/special-dl191.shtml

30

Wow, I never realized how similar flying was to being born.

31

Wind shear and turbulence are not at all the same thing, although both can be the product of convective activity (thunderstorms).

Turbulence is random and chaotic in nature – essentially the wind currents change rapidly and randomly.

Low level windshear is the result of a strong downdraft coming (usually) out of the bottom of a thunderstorm. In a mature thunderstorm, wind blows more or less straight down out of the center of the cloud. When this wind hits the ground it fans out in all directions.

If an aircraft flies straight through this area, here’s (a simplified version of) what happens. Say the aircraft’s ground speed is 150 kts. As it approaches the downdraft, the wind blows straight at the aircraft. If the wind is blowing 25 kts, the aircraft will “feel” 175 kts of wind over the wings. After passing through the center of the downdraft, the 25 kts head wind rapidly becomes a 25 kt tailwind. Apparent airspeed almost instantly goes from 175 kts to 125 kts. If 125 kts is below stall speed for the aircraft, then, as my dad used to say, “stall spin, crash, burn die.”

This effect is exacerbated by the pilots natural inclination to slow down going into the headwind to bring airspeed back on profile (imagine slowing to a 125 kt groundspeed so that grounds speed + wind = 150, then the wind shifts… now the aircraft is 75 kts slower than it’s supposed to be. It’s also amplified by the downward force while in the center of the downdraft, which will often cause a pilot to “trade airspeed for altitude” to keep from descending in the downdraft. If you read the linked article, that seems to be exactly what happened, they were way too fast, then suddenly way too slow.

Aircraft fly through changing winds all the time, and the effect is usually gradual and imperceptable. But low level wind shear caused by thunderstorms and microbursts concentrate the effect by being a 180 degree shift in a very small geographical area.

32

No, I know you’re lying and that you do it on purpose. I’ve seen documentation! (Cite: That Gary Larson Far Side cartoon with the pilots making a turbulence announcement and then playing with the controls and laughing. By the way, have you ever seen goats in the clouds? I hope not.)

Seriously, thanks for the as-always great and informative post.

33

I don’t like turbulence in the sense that I’m disappointed by a glass-smooth flight, but an occasional bit of chop along the way does help break up the monotony.

34

In 600,000 miles of flying ( got my statement today) I have only experienced anything more than light chop twice.
Once was coming coast to coast crossing the middle of the country, that 767 was bouncing pretty good as the pilot tried to find his way around some serious thunderheads.
The other trip was on an Airbus (A340) from Denver to LAX. We had a two hour gate hold in Denver due to weather in LA. Once we left the flight was smooth until we hit the approach to LA. I did not think that that large a plane could move in that many directions all at the same time. :eek: That plane did not so much fly that approach as it corkscrewed its way to the airport.
On both of those flights nobody gave the flight attendents grief about the seat belt sign being on. :slight_smile:

One tip on avoiding turbulence: Fly on flight without a meal service. Turbulence always shows up right as the meal is being served. Got to be one of Murphy’s laws.

35

(Small hijack) Next Tuesday’s *Wanda Does It * episode on Comedy Central has Ms Sykes taking flying lessons after a rough airline flight according to the ads.

I flew quite a bit in the US air traffic control system during my last job and trust me, the airline pilots and controllers are doing pretty much everything they can to get you guys out of any and all turbulence, even the light chop.

36

LOL! :slight_smile:

(Sorry, I know it’s not funny for the people who are stressed, but the “meep” really made me laugh…)

I’m neither a pilot nor a frequent flyer (though I’ve flown more often than some), but turbulence and flying have never bothered me. In fact, a pilot friend once took me up with him while he was working on getting his instructor’s license, and I had to keep assuring him that a little turbulence wouldn’t bother me (it was slightly windy that day). Of course, I have wanted to learn to fly ever since that day. :smiley: (There’s a photo of me behind the “wheel;” I have a terribly serious look on my face because it had just hit me that my friend was no longer flying the plane, having taken his hands off all controls and turned sideways to take the picture.)

37

When planning a flight you need to have fuel for the flight, plus a fixed reserve that you plan to arrive over the destination with, plus a percentage of your flight fuel as contingency fuel. This contingency fuel is supposed cater for weather diversions including altitude changes, or slower than expected groundspeed. So there would normally be fuel available.

Shagnasty, yes it’s less dense air which allows the aircraft to have a higher airspeed. I wasn’t sure though, how it affected the efficiency of jet engines.

38

I don’t mind turbulence as a passenger but as a pilot it just pisses me right off. I’ll be reaching over trying to do something with the GPS or something and my hands are jumping around so I can’t even hang on to the knob I want to turn.

39

ooohh. Now, THAT’S comforting.

40

Last year, I was flying from Denver to Houston on United as the last part of a trip to Bangkok (the Bangkok to Tokyo leg was incidentally so rough that they cancelled meal service but never got worse than “moderate chop” on the radio). The flight was smooth until we hit a thunderstorm line near Waco. It was pretty interesting to hear ATC guiding all flights at 1000 foot staggers through a small gap in the line of thunderstorm. I remember them calling our flight number with a traffic advisory with three planes to be advised of. When we went through the gap, I could see a flight 2000 feet above us flying in the same direction and one 1000 feet below coming the opposite direction. As each plane went through, it reported the level of chop to ATC.

As to turbulence and air disasters, it wasn’t a crash, but the only one I can think of off the top of my head was a JAL 747 out of Anchorage that lost the #2 engine (as in it fell off the wing with a bunch of leading edge machinery and some of the flaps), in heavy turbulence. They managed to turn the plane around and land it safely, but it was enough turbulence to put them in a 45 degree bank angle on their takeoff climb. Pretty incredible stuff.
http://aviation-safety.net/cvr/cvr_ja46e.shtml