A pilot explains turbulence | Hacker News Reader

A pilot explains turbulence

businessinsider.com

125 pointssohkamyung72 comments

Here's one of the best pictures illustrating the wake of an aircraft in flight I've seen: https://s00.yaplakal.com/pics/pics_original/7/3/7/4872737.jp...

Looks like a Tu-95 bear or variant.

Sometimes you eat the bear, and sometimes the bear eats you.

Patrick Smith, the author and eponymous "pilot" in the title, has been writing interesting articles about flying and a pilot's life for years. He is as much a traveler as he is a pilot and loves what he does. If you have any interest in flying or travel but have somehow not come across Patrick Smith before, check out his archive [1] and his book [2] Pilot Confidential, an update of his earlier book, Ask The Pilot, named for his now-defunct column at Salon.com iirc.

[1] http://www.askthepilot.com/archives/ [2] https://www.goodreads.com/book/show/16235130-cockpit-confide...

And here's the exact source of the businessinsider.com article - http://www.askthepilot.com/questionanswers/turbulence/

I can't recommend Patrick Smith's writing highly enough. I used to be somewhat uncomfortable when flying: the lack of control was extremely unsettling. But after reading Ask the Pilot for a while, I came to understand and respect the role of the pilot.

I would also strongly recommend his books, _Ask The Pilot_ and _Cockpit Confidential_ for anybody who travels (and especially for nervous fliers). Now I fly quite regularly, and love it.

Same experience here. The day after finishing Cockpit Confidential I experienced my first go-around landing in bad weather. I wasn't nervous because I had some idea why it occurred and what was happening in the cockpit.

I also find the Aviation StackExchange site [1] interesting. The weekly newsletter [2] contains just enough interesting stuff for a mildly interested occasional flier like myself.

[1] https://aviation.stackexchange.com/

[2] https://stackexchange.com/newsletters/newsletter?site=aviati...

Even better: become a pilot!

https://www.aopa.org/training-and-safety/learn-to-fly/how-do...

is it correct to use eponymous like this? I thought it implied that you were actually using the name: "Patrick Smith explains turbulence"

obviously language is dynamic, but I've not seen this use before, and it seems like it's the opposite of the meaning of the word.

Strictly speaking it isn't eponymy, since the column isn't named for Smith himself. But, while a stretch, it's an acceptable one, and one I've seen used not too infrequently elsewhere. As you say, language is dynamic, and we see here an example of that dynamism in action.

In a glider, turbulence is often the first indication that you are flying into a thermal that will lift you up, while the sinking or neutral air between thermals is often smooth. After having experienced this for a while, the onset of turbulence triggers positive emotions, even when you are in an airliner.

Yea! when the beep of the vario kicks in, is like: free fuel!

Personally, I love turbulence. I'm thoroughly disappointed when the pilot announces they'll be changing altitude to avoid it. It's literally the most interesting thing that can happen while flying.

You have an, um, interesting definition of "interesting".

Well, you have people flying aerobatics for fun, which provide much greater negative G forces than quite extreme turbulence. It's just a matter of personal preference; turbulence is completely harmless if you're strapped in reasonably tight :)

I'm actually one of those people who (occasionally) flies aerobatics for fun. It's a lot more fun if you can see out the front, which you typically can't in a commercial airliner.

I remember a conversation where a group of people considered whether we like turbulence or roller coasters. We managed to find represented all four combinations of liking neither, liking one but not the other, or liking both.

I don't like turbulence, but I became more comfortable with it by listening to the "From the Flight Deck" on channel 9 of United's in-flight entertainment (with live ATC audio). Unfortunately, I don't fly United that much anymore and it also appears that this is offered on fewer flights over time. But it was quite comforting to hear the pilot talking to an ARTCC about the turbulence we were experiencing, especially to learn that it was only "light chop" and the captain saw no need to change routes.

I like fun, tall, fast, soaring roller coasters. I hate jerky, upending coasters.

I flew from New York to London once, listening in to the ATC channel. Lots of fun. We passed Newfoundland, things got quiet. Then one aircraft came on line, saying "we are at such position and height, it's a bit bumpy, anyone got any advice?". Somebody answered that they were 10 minutes ahead, bumpy, too. Somebody said they were 2000 feet higher, very bumpy. The radio chatter died away with a final pilot saying the only thing to do was to "strap'em up and ride it through".

Me? I spent the next few hours preparing for turbulence that never arrived.

Two airplanes flying the North Atlantic Tracks [1] can be hundred of miles away. While you can adjust your altitude, you cannot move from one "lane" to another.

[1] https://youtube.com/watch?v=-aQ2E0mlRQI

There is nothing humorous about being thrown against the cabin ceiling and breaking your back, or neck, or getting a concussion. Do you equally enjoy being thrown from the 5th floor of a building? That temporary loss of gravity is almost exactly what a plane experiences in mild to severe turbulence.

You might want to read the article. 40 foot drops at the very outside, and 50 out of 2 billion passengers worldwide each year requiring medical attention. Sounds like less risk than walking the dog.

I always keep my seatbelt fastened while sitting in my seat.

I am so jealous! I hate turbulence, and I can't even explain why. I have a USPA C license - I've flown in enough rickety planes to get certified to skydive into public venues - and turbulence still causes my blood to boil.

You would love this: one time I flew from Chicago to Ithaca on a small commuter plane, and the pilot told us it'd be bumpy due to area storms. It got pretty bumpy, and the girl sitting next to me was a lot worse off than I was, I didn't know her but she grabbed my hand and was squeezing so hard it hurt. Maybe ten minutes into one of the turbulent spells, the cockpit door flew open and the pilot and co-pilot were going "YEE-HAW" and doing the rodeo rope. My chin hit the floor, and so did everyone else's when we all realized they'd been hitting the roughest parts of the storms they could find on purpose.

Hilarious but sounds mildly illegal.

Fairly certain it wasn't even remotely illegal before 9/11/2001, after which it probably did become pretty illegal (for the opening of the cockpit door).

It'd be pretty hard to ever prove anything, it's not like they can really go hundreds of miles off the flight path. In my case, the cockpit door opened completely on accident, or at least because of what the pilots were doing, the turbulence is what bumped the door open. Now that the doors are locked, it wouldn't happen again. They blushed and shut it as quickly as they could, and later offered an apology that didn't openly admit to doing it intentionally, but reading between the lines was as close as they could go.

It wasn't particularly enjoyable at that moment, but it is really funny, and I'm glad it happened.

A friend of mine was on a flight that hit turbulence and suddenly dropped a few hundred feet. People were basically panicky until some texan towards the front waved his hat in the air yelling "yee-haw", which sucked all the tension out of the air.

Haha, that would have been totally awesome!

And that reminds me of two more turbulence stories I have.

Once on an international flight from Spain to the US, we had a single turbulent drop. They were serving coffee, we were over the ocean and only a couple hours from home, and suddenly in a split second no gravity and then WHAM! A bunch of coffee spilled, they stopped the coffee service, and everyone got quiet for the rest of the ride fearing another drop. Someone breaking the tension would have been sweet relief. There was no other turbulence either before or after, and it's probably a real thing, but because of my YEEHAW experience, I've always had a small suspicion that the pilots did it on purpose. Maybe one of them liked one of the flight attendants or needed a second coffee. :P

We did get a tension breaker on a flight into Maine a couple years ago during hurricane season. The half hour before landing was just awful, we flew right into the hurricane and there was so much turbulence everyone was completely freaked, the plane was bouncing all over the place, and the tension made worse by crying babies. (My fault, half the crying babies on the plane were mine and my cousin's crying babies, btw, I have nothing against crying babies unless I'm on a plane and it's turbulent.)

When the plane touched down and stopped shaking, suddenly it got real quiet, all the babies stopped crying and you could hear a pin drop. Just long enough to be uncomfortably quiet, when one of the flight attendants hit the PA and with all the vocal fry he had announced "...aaaaaaaaaand that's how you do it, folks." The plane exploded in laughter, and a few people actually cried with relief.

My story:

Years ago, I was on a flight where it started getting bumpy. Seat belt sign comes on. It starts getting worse. The crew starts preparing for landing. It gets worse.

Captain announces: "Flight attendants sit down now!" That's never a good sign.

It gets worse.

We attempt to land, but apparently we hit very high wind sheer at 1000 feet, and they go full throttle and abort the landing. We wind up bouncing around in a holding pattern in the worst turbulence of my life for about 20 minutes waiting for another chance to land. Eventually, they decide it had gotten enough better to try again. We successfully land although it is very very bumpy.

Captain announces, "I need a beer."

My dad was flying a DC-3 in the southwest one day, clear sky, no trouble expected. Suddenly, the plane started shaking violently. All he could do was reduce the airspeed to the minimum (to reduce the stress on the airframe) and hold on.

He radioed in to report the turbulence so other traffic could avoid it.

After he landed, the plane was inspected and found that the wings had pulled rivets out.

Trying to land during a thunderstorm in Grand Rapids, Michigan, we had two bumpy go-arounds like that. Then the pilot said something like "well folks I'm sorry but we need top up a bit before giving this another try."

The plane then flew directly across Lake Michigan to Chicago Midway, made a hard left turn in sight of the runway, and about 30 seconds later we were on the ground. Not your normal approach pattern! ATC must have cleared the other planes out for us. Maybe our pilot declared an emergency, I don't know.

We stretched our legs for about half an hour in the terminal while they fueled the plane, then headed back to Grand Rapids. By that time the storm had moved on and we landed in smooth clear air.

Getting to less than 45 minutes fuel on an IFR flight plan (all airliners) is an automatic full on emergency. Usually you request urgency from ATC before that so you can land with just over 45 min (+ whatever is needed for taxiing) of fuel available to avoid having to use emergency procedures and a lot of paperwork.

So probably that's what your pilot did as well. Two go-arounds and then flying to the alternate airport would usually get you very close to the 45 minute final reserve on normal fuel planning.

You are absolutely right. That is literally my definition of a good time on a flight. My experience in smaller planes is rather limited, but the time I've spent on those little prop driven puddle jumpers has always been more enjoyable, as the ride does tend to be a bit bumpier.

I've also been on planes with friends who have an abject fear of flying. Throw in a dash of turbulence to a flight like that, and there is literally nothing you can do temper someone's fear of the situation (short of sedatives). Definitely not as fun.

Random aside, I went hang gliding once (tandem w/experienced pilot) and ended up going on a particularly "bumpy" day, which all the experienced pilots said with a positive attitude. Bumpy days are days with lots of updrafts and therefore more potential flight time per launch. Definitely felt like turbulence in an airplane, minus the walls and windows ;)

I've still yet to jump out of a perfectly good airplane, but it's definitely on my bucket list.

> there is literally nothing you can do temper someone's fear of the situation (short of sedatives). Definitely not as fun.

It's so weird. I know consciously that turbulence isn't a safety risk. I know that next to zero planes have gone down due to turbulence, and that specs for modern wings allow for like 15 vertical feet of flex. I've watched shows on the hurricane researchers that voluntarily fly into worse turbulence than any commercial flights have ever seen. It feels physiological, because my body just doesn't seem to care what my head thinks. I wish for sedatives or beta blockers, or something. I can't temper my own fear. Average heavy turbulence is no worse that riding a jeep on a dirt road, and nobody in a jeep fears the vehicle is going to fly apart. (And by nobody, I mean me and imagine it's true of everyone)

> I've still yet to jump out of a perfectly good airplane, but it's definitely on my bucket list.

It's way crazy fun. Dangerous but I don't regret my time skydiving even though I don't do it anymore. If you spend some time in a wind tunnel first, you may be able to get more out of your skydiving experience. Those weren't really a thing when I was jumping, but now they're all over.

This is neither here nor there, but I never jumped out of a perfectly good airplane. They were all crappers. One time I jumped out of a plane than crash landed on it's return (pilot was fine). It might have run out of gas because the DZ people are stingy, and not because the plane had a problem, but still it was a dumpy ride, and most planes I jumped out of I'd rather have jumped than stayed in for the landing. :P

It's interesting to hear that some people actually enjoy turbulence. You would think that anything that introduces stress to aircraft components would be a cause for concern when travelling in a metal tube with little chance of survival in the event of catastrophic failure. Planes are reliant on routine and properly thorough maintenance which isn't exactly a guarantee given the time or cost constraints. And when you couple this with the fact that there are planes flying that are very near their end of life expectancy how could you not help but worry when turbulence hits.

Well, just remember that flying in no turbulence is like 95% of the stress, turbulence only adds a little bit. (I made that number up, but I imagine it's really close to accurate.) Planes are designed for this, they expect flex in the structure and plan for it to happen. Commercial airlines track metal fatigue, and they have allowed safety margins for stress that allows for "normal" to be pretty far past what most of us have ever seen, before they're even concerned. Cars and boats and buses and trains all flex a lot while traveling too. Planes feel worse, but really they're not.

So I can totally understand at the conscious level why some people enjoy turbulence. I just wish I could enjoy it too, instead of having a level of fear that is clearly disproportionate to the relative risk.

Relative risk wise, my choice to skydive is extremely more dangerous and risky than flying in turbulent aircraft, so I'm pretty far past any reasonable safety analysis.

FAR 25.303 requires a substantial safety margin for structural loads.

§ 25.303 Factor of safety.

Unless otherwise specified, a factor of safety of 1.5 must be applied to the prescribed limit load which are considered external loads on the structure. When a loading condition is prescribed in terms of ultimate loads, a factor of safety need not be applied unless otherwise specified.

https://www.law.cornell.edu/cfr/text/14/25.303

Airplanes in the United States are extraordinarily well maintained. Certified airplanes (which include all airliners) must be inspected annually to maintain airworthiness. Yes, you do hear stories of inspections sometimes being pencil-whipped, but these are by far the exceptional cases. The inspection has to be at least supervised (if not performed) and signed off by a certified Airframe & Powerplant (A&P) mechanic with an Inspection Authorization (IA). The A&P certificate requires training, passing a written knowledge test, passing an oral grilling, and passing a practical test. The IA requires additional training and testing. Someone with that much invested is not going to screw around.

The annual inspection itself is detailed and thorough, not a quick eyeball. Any discrepancies or issues (squawks) the A&P discovers are potential followon work. Serious squawks must be addressed before the airplane is airworthy, i.e., legal to fly.

Further, any airplane flown commercially (be it for flight instruction, aerial survey, or transportation) must be inspected to the standard above after every hundred flight hours. Commercial operators have special certificates to allow them to conduct business that they likewise will not jeopardize by foolishly cutting corners. Commercial pilots have hundreds or thousands of hours and tens of thousands of dollars invested, so they also have a huge personal stake in playing by the rules.

Turbulence is no fun. Catastrophic failure would be even less fun. Safety rules, procedures, systems, and backups are in place that keep safety at the forefront. The airplane can take it. People with significant stake personally and financially have checked, rechecked, and signed off saying that it is safe.

> nothing you can do temper someone's fear of the situation (short of sedatives)

Also known as the B. A. Baracus approach.

I fly a nice stable Piper Cherokee Six, so my calibration is probably out of whack for what a hang glider considers to be a bumpy day. The thought of being suspended by a few strands of nylon in turbulence looking at nothing but ground hundreds or thousands of feet below is unsettling.

turbulence on lawnmower planes is a lot of fun!

The no-kidding roughest parts of thunderstorms can cause airframe structural failure[0]. The captain and first officer were almost certainly attempting to bring levity to a stressful situation, not recklessly endangering the lives of everyone on board and jeopardizing their livelihood, pensions, and certificates.

[0]: http://airfactsjournal.com/2017/07/thunderstorms-airplanes-p...

It's a little more complex than that "In thunderstorm accidents, the sequence usually starts with a loss of roll control. That is why keeping the wings as level as possible is primary. If roll control is lost, the natural tendency of the airplane is to enter a spiral dive where the airspeed increases rapidly and is soon outside the envelope. Then the airplane is in a condition where either turbulence or use of the controls can cause a structural failure."

In other words failure to respond correctly is the problem, not the airframe.

Lol, that reminds me of the plane scene from Almost Famous: https://m.youtube.com/watch?v=WHOE4UfoimY

Maybe a little bit turbulence. I had a flight from LA to SEA that they couldn't serve drinks on the whole flight and the overhead bins kept opening up.

I was on a cruise ship once where they announced they were changing course to avoid a storm (not a hurricane by any stretch). I was pretty disappointed. :-)

That's another experience I'd love to live, open ocean storm, giant waves. Unfortunately I can't seem to come up with a way of doing it that doesn't statistically shorten my life expectancy considerably (unlike turbulence in an airplane ;)

This is why they do that https://youtu.be/jup-5Xu1OOU

Similar, but viewed from the outside - https://youtube.com/watch?v=EkS_f6Aztxk

This was considerably funnier last time I saw it dubbed with Rod Stewart's "We are sailing"

Yes, I love having someone who's 270lbs fall into my lap while I'm holding a drink. What's not to love about that. Or smelling vomit or listening to a hysterical woman screaming or a child crying. Sounds awesome.

Yes, my enjoyment is entirely conditional upon not being immediately in the company of people who don't enjoy it all, like most other activities.

Am not worried about mid flight turbolence having flown myself I kinda know it all works, but we had strong guts on approach to Dublin once and that was extremely stressful

It's well known that gripping the armrests provides lift to the airplane - the tighter the grip, the more lift. So next time you experience turbulence, you know what to do!

This is a common belief, but it's not correct. You have to both grip and pull upwards, otherwise the net lift is zero and you will die.

It gets even more complicated. If the plane suffers and inversion, as during barrel rolls and loops, you have to coordinate pushes and pulls with the orientation of the plane. Otherwise, the maneuver may suffer a distortion and fail to recove properly!

I hear it works better if you soil yourself. It helps smooth out the boundary layer.

Am I on reddit?

This is bad ass. 777 wing test. https://www.youtube.com/watch?v=rak2HldVp9M

That amount of deflection is insane, you'd never see that in normal flight. (Pilot here.)

The article mentions “turbulence penetration speed” or Vb and "maneuvering speed" or Va. Simplistically these are speeds below which the wing will stall before it breaks. The wing is designed to gradually stall in these conditions not abruptly. You really won't feel it unless you know what you're looking for and you're reasonably experienced as a pilot. The wing just kinda gradually craps out rather than being over stressed, and just as quickly starts to fly normally again.

Seriously the plane can structurally take extreme turbulence when flown at or below the proper safety speed, even though by definition at extreme turbulence the pilot is just along for the ride (the plane is not considered controllable with extreme turbulence, you get to pick a speed and kinda sorta a general direction, you don't get to control the altitude or the attitude). I've not experienced extreme turbulence and have no desire to, but have been in severe turbulence and don't need to do that again. But the plane is alright.

Another fun fact, 99% of what people consider bad turbulence is less bumpy than the average bus ride. It's just that being in the air messes with the subjective importance people assign to turbulence.

This. I know it, and you're right, flying makes it feel worse. It helps me a little when I'm in flight turbulence to close my eyes and pretend I'm in a bus on a dirt road. But I can't figure out how to ignore it or just feel calm and rational, like I want to.

Microbursts (https://en.wikipedia.org/wiki/Microburst) can be very dangerous. I'm not sure if these would be correctly classified as "turbulence", though.

I was on a wide body a few months ago and we had a very sudden burst of pretty intense turbulence -- we'd apparently hit the wake of an A380

I've been on a smaller jet where on approach to O'Hare, banking left over the lake, we must've hit a aircraft vortex. We went from maybe 20-30deg bank to something close to 80 in an instant while simultaneously getting that lovely zero g feeling if falling. Lasted like the article says maybe only a few seconds but I'd be lying if it didn't get my adrenaline going and a few expletives out of me.

My favorite explanation (though not comprehensive) was in The Hunt For Red October: https://www.youtube.com/watch?v=htTLYO-zOww

I like a bit of "chop" (light to moderate and rhythmic turbulence). I really really do not like phugoid oscillations on an international night flight over the north pole. That was pretty creepy.

Turbulence in flight might not crash the plane, but do sit down and wear your seatbelt when advised to.

A sudden drop of 40 feet can propel you upward toward the ceiling and break your neck.

This is a straight rip from Cockpiy Confidential, which was a really great book

As someone very much interested in flying, I find this article perfect.

If he could explain turbulence, that would be good for a Nobel Prize.

Yep. Supposedly, Heisenberg thought the explanation of turbulence worthy of putting the question to God. And didn't expect an answer to be forthcoming. [1]

[1] https://en.wikipedia.org/wiki/Turbulence

A bit of a tangent, but a comforting thought is that unusually strong turbulence counterintuitively has a beneficial effect on fatigue crack propagation. Aluminium always has cracks and they're keep growing but a heavy load that opens up a crack plastically deforms the material around the crack tip so that its natural state is for the crack to stay open. But the rest of the structure forces it closed. Once it's in this state, subsequent smaller higher frequency loads don't apply the usual damaging tensile stress to the crack tip so it doesn't grow like it otherwise would have.

Not going to stop the wings falling off on your flight though, but it might help the next guy if it's some South American airline that never maintains its planes :P

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