Severe Turbulence

[terryp]

Hi All,

I am a PPL holder and have been flying for over 10 years so have had my fair share of turbulence in light aircraft and as a passenger on commercial flights.

I arrived back from San Francisco earlier today and have experienced what I can only describe as the scariest thing in my entire life. Flying British Airways 747-400 from SFO, we were about an hour into the flight and the cabin crew had just finished handing out the first food serving as we started to experience some mild turbulence. Enough to make a nervous flyer uncomfortable but nothing than concerned me and the seatbelt signs were left off.

After a few minutes of this the turbulence went from mild to violent with the 747 being thrown around like I could never imagined. This started to make me a little uncomfortable, even as an experienced pilot and passenger, the seatbelt signs remained off and the cabin crew were still going about their business.

All of a sudden the 747 was flung violently upwards then slammed downwards as is if someone had hold of it by the tail. The engines had a clear loss of power and the aircraft went into a nose down attitude and began to bank right, all while still violently shaking, passengers screaming and trays drinks flung around the cabin. To be honest, I wasnt sure we were going to recover.

The seatbelt signs went on as the flight crew tried to regain control of the aircraft and put power back onto the engines. While they managed to do this we remained flying in these conditions for a further 45 minutes or so, the longest of my life I might add, the intermitently violent spells of turbulence until we reached the Atlantic and leaving Canada behind.

I spent the remaining 6 hours of the flight terrified at every jolt and its left me feeling I never want to get in an aircraft ever again! Now while I hope that won't be the case it has definately unnerved me significantly and I'm questioning whether I would want to feel that way again.

Has anyone else ever experienced this?:sad:

[WILCO.XMG]

WOW. Sounds like quite an ordeal.

I like many others i'm sure, always feel safer when i am in charge.

When i drive a car fast it doesn't worry me as i know my limits and know i can handle it.

When i sit in with someone who also drives it fast. I am terrified.

Its probably just human emotion.

P.S. I'm sure you will get over your ideal. It would have been good to have a word with the pilot when your were disembarking to see what actually happened. The less big a deal he made of it probably would have comforted you perhaps.

[Shaggy Sheep Driver]

If the seatbelt signs remained 'off' untill the last bump, was it really that bad? usually airline flight crew are only too happy to have it 'on' even in very light chop.

[terryp]

Shaggy, I can assure you yes it was that bad, given the cabin crew were instructed to cease service and remain seated and belted for almost an hour of flight is an indication of that. The lack of seatbelt only echoed the cabin crews comments which were that the turbulence was completely unexpected.

[Katamarino]

I don't believe that turbulence would cause the engines to power down. It's a bit of a guess, but my first impression would be that they were merely slowing down to best turbulence penetration speed. Certainly not "struggling to regain control"!

[MichaelJP59]

Sounds bad, did the flight crew come on the PA to reassure the pax? I would have thought an actual engine flame-out would result in a formal report, did you check?

I've only had it really bad once on a commercial flight LAX-LHR when everyone's drinks hit the overhead lockers and anyone not buckled in was in zero-g for a short time. I wasn't too worried as these days an aircraft breaking up in turbulence is extremely rare. Risk of injury when not strapped in is the main problem. I certainly always have my seat belt on when not actually out of my seat.

[thing]

Odd that, my son had exactly the same thing Brisbane-Perth last week. He's a very experienced business flyer but the turbulence was so bad he just wanted to get off. Passengers were crying etc and the TD's were strapped in for most of the flight, it lasted for 5 hours.

Apparently they were flying against an exceptional jet stream and couldn't get above FL270 otherwise they would have been virtually hovering. The return trip that evening took 3hrs 40 minutes (normally 5 and a bit hours.)

I remember flying back from Portugal in 2000 when we had the bad storms in UK. The captain came on and said we were flying against a 120 kt headwind....

[terryp]

Katamarino, I didn't offer a reason for the power down of the engines, I said there was a simultaneous noticeable loss of power. Whether this was the pilots doing or not the fact the aircraft had been put into a nose down right bank attitude does not suggest full control. Also the pilot applied high thrust on the engines shortly after and maintained a higher thrust throughout the turbulence.

Michael, several passengers did end up wearing eachothers drinks. As for the cabin crew I was quite disappointed as the pa consisted of 'the captain had put on the seatbelt sign due to severe turbulence, he has also instructed the cabin crew to cease services and remain seated also. He expects this to last 20-30 minutes'. I always keep my seatbelt strapped and while I know that it's highly unlikely an aircraft would ever break ip these days it still scared the s@@t out of me.

[FANS]

A reminder to always a seatbelt, and that flying at 500mph, 38,000 ft above the earth in an aluminium tube is not as simple as people now consider.

Aside from this, it still amazes me the risks that some private flyers will take with the weather, especially given their lack of experience.

[terryp]

Thing that's a good point, we had a 110-120kt tail wind according to the 'moving map' info until we got out over the Atlantic and the flight time was 9 hours against the usual 10

[Katamarino]

If you're a pilot you'll know that "temporary changes in attitude or altitude" are part of the definition of turbulence. So, following your logic, that means that any aircraft that has ever encountered turbulence was "out of control"! I'd expect that sensationalism from a journalist, not a pilot :)

[piton]

From what the OP describes I would think the flightdeck crew were busy trying to fight the unusual attitudes due to the turbulence for the first minute or so of the incident. After all they are also just human and the seatbelt sign might have slipped their mind(s). If Clear Air Turb hits when cruising near maximum performance altitude there isn't much "room" to stay out of both high and low speed buffet zones on the speed tape/airspeed indicator and that would have held their attention for sure!

The fact that engine noise died out could just be due to throttling back if an overspeed was imminent (often the case on my 737NG when caught by a sudden wind change that can accompany turbulence).

Terryp - why don't you post in SLF or questions? - maybe including the flight number and date in the title might get an answer from a BA person with more info.

I do think it's a bit of the poor show if you heard nothing from the flightdeck crew....

[terryp]

Katamarino, yes you are correct and as a pilot, if I'd have been the pilot in command that logic would have indeed been applied as it has been before in my flying experience. Wilco makes a very valid point in that when you are not in control, i.e. the passenger, the reaction to such a situation is somewhat different.

Thanks Piton very helpful reply, I might just do that see if I get a response. We were at our cruising altitude 37000 feet so you explanation makes sense, it would have been good to catch the pilot on disembarking but to be honest the main thing on my mind at that time was getting off :)

[IO540]

Was this at night, or in daylight?

[aviate1138]

Flying over the Rockies can be extremely turbulent at times. Used to commute fairly often from LHR to SFO via JFK and the usual flight I took from JFK to SFO was an American Airlines flight AA5? or similar. This was back in the late 70, early 80's. I always stayed strapped in as on more than one occasion I had seen trays/drinks passengers and flight attendants doing the zero G routine. Even heard the Captain [AA had an audio channel for aviation geeks] ask for a number of level changes and say at one point "I have been flying this route for years and I have never had so much turbulence." Because of nearby traffic also requesting level changes we often just had to grin and bear it.

It was seeing the amount of wing flex that kept my eyes wide open!

[AdamFrisch]

The worst I ever had was coming back to London from LA on Virgin's A400-600 a couple of years ago. I knew it was going to be bad when the captain said "the good news is that our flying time is just 9hrs today, the bad news is that that means high turbulent winds". It turned out be like the OP described and people were crying. A gentleman in the middle row next to me was screaming out "oh my god, we're gonna die!" constantly, which didn't help:eek:

Even though I know how tough they're built, it wasn't very enjoyable experience and I was scared. Somehow when you're driving yourself it feels less bad even when it's bad.

[IO540]

Somehow when you're driving yourself it feels less bad even when it's severe.

That's what I keep telling my girlfriend :)

The reality is that all the objectively scary flights she has had were in airliners, whereas flying with me the most she had were a few bumps.

But there is a big psychological difference in that most people trust the two pilots up front who wear smart uniforms, many have great hair (grey is very reassuring), they speak with posh (reassuring) accents, and everybody assumes that nothing will happen.

Structural failures are indeed extremely rare in the USA and Europe but plenty of flights are extremely rough because provided that the weather etc is within the legal parameters you have to fly else you get sacked.

[iwrbf]

terryp,

with all due respect, but as a PPL holder you should be aware about the definition of "severe turbulence".

The situation you describe was far from that. In severe turbulence, sorry for the drastic words, you would have seen people sticking in the overhead bins when not fastened on their seats. Given the fact that there were FAs at work at this time, this was far from severe.

I'm not a 747 driver, but nonetheless, you can take my word: this ugly old thing will still smile at the turbulence you're experiencing while you get bruises from your seat belt. Don't mind...

I guess there was just mild turbulence forecast in the area so the guys on the best seats decided not to overreact. When the turbulence got worse they (or AT?) throttled down and they changed altitude and direction trying to minimize the rodeo :-)

Don't take this as an offense, please. I just want to tell you: You're safer as you think you are in turbulence. When was the last time a plane threw away vital parts in turbulence (flown by a professional crew, that is...).

Kind regards,
Peter

[Pace]

Terry

I have only experienced severe turbulence once. Usually one pilots description of mild, moderate, heavy, or severe will vary by what they have experienced themselves so one pilots description of mild can be reported as moderate by another.

I flew some PAX to Nice. We had a warning to expect severe turbulence between FL200 and FL300.

Descending from FL360 I warned the PAX to secure their seatbelts as we were going to experience a very bumpy ride.

The air all the way down into Nice was as smooth as a babies bottom much to my embarassement as I am sure the PAX must have thought what sort of Wally Captain they had up front.

Taking the aircraft back to the UK empty we took off on a more northerly SID passing FL200 all hell let loose with the aircraft almost uncontrollable. Violent Pitches and wing drops. Cupboards flying open items flying everywhere.

I asked for an immediate climb to above FL300 due to severe turbulence.
FL200 to 300 normally shows around 1000 fpm in the Citation back to 600 fpm in the high 20s.

The VSI was showing over 3000 fpm all the way through FL300 where the air went dead smooth.

Pace

[Mark1234]

Reports should be standardised, but the experience will depend to quite a large extent on the size and wing loading of the aircraft. Light wing loadings will be more affected by gusts.

Just for the record, ICAO doc 4444, appendix 1, detailed reporting requirement says:


The following specifications apply:

Light — Conditions less than moderate turbulence. Changes in accelerometer readings less than 0.5 g at the aircraft’s centre of gravity.

Moderate — Conditions in which moderate changes in aircraft attitude and/or altitude may occur but the aircraft remains in positive control at all times. Usually, small variations in air speed. Changes in accelerometer readings of 0.5 g to 1.0 g at the aircraft’s centre of gravity. Difficulty in walking. Occupants feel strain against seat belts. Loose objects move about.

Severe — Conditions in which abrupt changes in aircraft attitude and/or altitude occur; aircraft may be out of control for short periods. Usually, large variations in air speed. Changes in accelerometer readings greater than 1.0 g at the aircraft’s centre of gravity. Occupants are forced violently against seat belts. Loose objects are tossed about.

[gpn01]

Hi All,

I am a PPL holder and have been flying for over 10 years so have had my fair share of turbulence in light aircraft and as a passenger on commercial flights.

I arrived back from San Francisco earlier today and have experienced what I can only describe as the scariest thing in my entire life. Flying British Airways 747-400 from SFO, we were about an hour into the flight and the cabin crew had just finished handing out the first food serving as we started to experience some mild turbulence. Enough to make a nervous flyer uncomfortable but nothing than concerned me and the seatbelt signs were left off.

After a few minutes of this the turbulence went from mild to violent with the 747 being thrown around like I could never imagined. This started to make me a little uncomfortable, even as an experienced pilot and passenger, the seatbelt signs remained off and the cabin crew were still going about their business.

All of a sudden the 747 was flung violently upwards then slammed downwards as is if someone had hold of it by the tail. The engines had a clear loss of power and the aircraft went into a nose down attitude and began to bank right, all while still violently shaking, passengers screaming and trays drinks flung around the cabin. To be honest, I wasnt sure we were going to recover.

The seatbelt signs went on as the flight crew tried to regain control of the aircraft and put power back onto the engines. While they managed to do this we remained flying in these conditions for a further 45 minutes or so, the longest of my life I might add, the intermitently violent spells of turbulence until we reached the Atlantic and leaving Canada behind.

I spent the remaining 6 hours of the flight terrified at every jolt and its left me feeling I never want to get in an aircraft ever again! Now while I hope that won't be the case it has definately unnerved me significantly and I'm questioning whether I would want to feel that way again.

Has anyone else ever experienced this?:sad:

Having flown SFO-LHR a number of times (albeit as pax on UA 777's) my guess is that an hour into the flight would put you around Reno (or just a bit further East given the tailwind you had). I suspect therefore that what you experienced was something that's not actually uncommon and is known as rotor. It's an effect associated with Mountain Lee Wave and you get a lot of wave effect to the East of the Sierra Nevadas which are lined up perpendicular to the winds blowing in off the Pacific.

I've experienced rotor first hand a number of times when flying out of Minden (just South of Reno). If you're not expecting it, it's very, very unpleasant. For a PPL I'd fully expect you to be uncomfortable about flying through it. As a glider pilot, I've actualy used it numerous times as a way of gaining height in order to benefit from the smooth rsing air above it associated with wave. Minden is one of the World's most renowned soaring sites precisely because of its location which makes it ideal for wave conditions.

Usually ATC will advise airliners when there's known wave in the area but, like the weather, it's not always completely predictible. So, combine the unexpected sudden onset of the situation with the possible lack of awareness/experience of the crew in dealing with the problem (amazing how many CPL's don't know about thermals, wave and rotor) and thinks may have become a tad frantic for a while!

[draglift]

As an airline pilot who has been flying airliners for nearly 30 years I would like to make a few comments on the big differences between the pilot's experience of turbulence and the passenger's. I have no doubt that you found the experience very frightening. The fear of falling is natural and even airline pilots who are passengering feel that temporary sense of alarm when the plane suddenly drops. I wasn't there on your flight and I could be totally wrong but this is my opinion:


After a few minutes of this the turbulence went from mild to violent with the 747 being thrown around like I could never imagined. This started to make me a little uncomfortable, even as an experienced pilot and passenger, the seatbelt signs remained off and the cabin crew were still going about their business.


If the seatbelts signs were off and the cabin crew were still going about their business although it seems to you to be violent it is likely to have been nothing more than light turbulence. It is most unlikely that the pilots forgot to switch on the seat belt sign. It is more likely they judged it as light chop that did not merit the seat belt sign.


All of a sudden the 747 was flung violently upwards then slammed downwards as is if someone had hold of it by the tail. The engines had a clear loss of power and the aircraft went into a nose down attitude and began to bank right, all while still violently shaking, passengers screaming and trays drinks flung around the cabin. To be honest, I wasnt sure we were going to recover.


Turbulence does not cause the engines to lose power. If the airspeed suddenly increased the autothrottle would have commanded a reduction in power. Turbulence penetration speed is normally less than cruise speed and it is likely that the pilots selected a lower speed and the engines reduced thrust accordingly. Light to moderate turbulence will knock over drinks and trays with associated gasps from passengers. An abrupt change of 3 degress nose down feels like a steep dive to passengers.


The seatbelt signs went on as the flight crew tried to regain control of the aircraft and put power back onto the engines


The autopilot stays engaged in turbulence. Some aircraft have a turbulence mode where the priority is towards level flight rather than chasing an altitude. The flight crew would not be "trying to regain control of the aircraft" but would be allowing the autopilot to level the wings and the autothrottle to maintain a target airspeed. As the airspeed is likely to be up and down in turbulence it is likely the engine thrust will be too.

Incidentally if the aircraft experienced severe turbulence the flight crew are required to make an entry in the tech log. I've only had to do it twice in almost 30 years of flying. Severe turbulence does not normally last more than a few minutes. The turbulence you encountered may well have been unexpected. Pilots have weather charts with areas of forecast turbulence shown on them, but there are often areas with nothing shown that have unexpected turbulence.

I have been at a baggage carousel before in uniform waiting for my bag and heard a nearby passenger also waiting for his bag shouting excitedly into his phone that there was "unbelievable turbulence" and the plane "almost came apart". The turbulence was never more than light occasionally moderate and we had had the seatbelt signs on for about 20 minutes of the 8 hour flight. Of course he might have been on a different flight and been waiting for his bag at the wrong carousel but I doubt it.

[mad_jock]

I thought I had been in severe turbulence.

Then I flew into Vagar in the Faroes. Everything was readjusted to light before that.

[Dave Gittins]

One of the joys of flying internal US flights is the Comms channel on United's flights. From listening to that on a few occasions, US pilots seem almost paranoid about getting and giving ride reports.

I guess your bout of turbulence must have been pretty unexpected if nobody had reported it.

[The Dead Side]

I like many others i'm sure, always feel safer when i am in charge.

I have to agree, I will happily sit in the left hand seat of a PA28 and bump around merrily at 2500ft on a hot summer's afternoon. Even in the right hand seat with someone else's hands wrapped around the controls, lumps and bumps will go very much unnoticed.

At 35,000ft things change somewhat (for me as a passenger at least), I have no problem with the turbulence, however with the monotony of a 4 hour flight with little to do, comes the propensity to notice the smallest of differences. I suppose sitting without an instrument panel and constant ATC chatter leaves one to speculate further over insignificant changes and apparent oddities.

I can vividly recall a flight back from the Dominican Republic to London (this was when I was around 11, so the memories maybe slightly enhanced...), it was a Virgin A340. Nothing was too eventful at first, however a couple of hours into the flight we experienced the clear air turbulence which is likely to only distract a more nervous flyer. A couple of minutes later, the seatbelt sign went on - I imagine even a frequent flyer may start to wonder what maybe in store after the ominous chime.

Anyway, over the next half an hour, the intensity of this turbulence increased to the extent the cabin crew stopped service, and were asked to be seated. By this time, it was no more than moderate, however instead of dying out, this turbulence went on for at least 4 hours. I wouldn't describe this as scary (no unexpected hundred foot drops or the like) but the continuity certainly managed to turn my stomach upside down.

I think everyone has their own experiences (I'm fairly young, so I haven't many yet), but I think it's interesting how situations differ due to the psychological situation the person is in.

[IO540]

I am not an airline pilot :) but I do think airliners will ride out turbulence because they want to stay on track to keep to their schedule, whereas a private pilot with passengers is more likely to do something about it.

Also airliners fly high where there often is clear air turbulence over long distances (the jet stream) whereas at GA altitudes, say FL100-FL200, once you are above the clouds the air is normally completely calm. I have done plenty of 4-7hr IFR flights and none of them had any significant turbulence enroute.

The longest bit I recall was a flight across the Alps, about FL170 i.e. about 8000ft above the terrain (down to the Adriatic) and there was a fairly gentle up/down ride. Nothing harsh, but a bit like being on a boat. Lasted about 15 minutes.

[Pace]

The best way as a pilot is to go with it I have even slapped my side and proclaimed " Ride em cowboy " :)
In twins and being slightly hair light I can remember going to the hairdresser after a heavy flight in a twin and the hairdresser pointing out a 1 inch cut from hitting the roof so belt in and hold onto something?
PAX are the big problem especially in GA where even in jets you have that personal contact the crew of heavies do not.
There is nothing much you can do but warn them, make little of the turbulence, slow down or change levels.
Some PAX love turbulence! Probably the type who love fairground rides. Yes I have had some who get a buzz from turbulence.
At the other end of the scale some think the wings are about to fall off reassure them with tales of this is nothing you wouldnt believe what these birds will tolerate.
Smile, look calm, joke tell them that everyone on the radio is complaining even the heavies otherwise they will think its just you or the aircraft is not up to it!
Even then some will be petrified.

Really do read your PAX especially in the company I can remember flying a lady in a private jet.Not a turbulence thing but something quite beautiful.

We were on auto at FL370 over the Alps with the most stunning views of the Alps covered in snow I had seen. We came to a sharp turning point and the aircraft banked to the new course.

Grabbing my camera I clicked a few shots.

The owner rang me stating that the female PAX had complained that I was doing steep turns over the Alps taking photos!!! I pointed out that I was very unlikely to be handflying at 37K in RVSM airspace? So beware of PAX if your in Ear or eye shot of them!!!

I am not an airline pilot but I do think airliners will ride out turbulence because they want to stay on track to keep to their schedule, whereas a private pilot with passengers is more likely to do something about it.

Also airliners fly high where there often is clear air turbulence over long distances (the jet stream) whereas at GA altitudes, say FL100-FL200, once you are above the clouds the air is normally completely calm. I have done plenty of 4-7hr IFR flights and none of them had any significant turbulence enroute.

10540

The worst turbulence I have ever experienced was between 20 K and 30K over the Alps and not clear air turbulence but mountain enduced so dont believe that assumption.
No the airlines or business jets dont just ride out turbulence to keep on track. We request (sorry demand massive deviations to avoid large CBs)
Clear air turbulence gives little option other than to climb or descend and reduce speed but stick on track.
What do light GA pilots do lower level? Land!!!




Pace

[Shunter]

I seem to recall that the ATPL theory notes described severe turbulence as creating "a risk of structural damage".

I've had 2 experiences of what I'd call strong turbulence. First just south of Dewsbury inbound to Leeds which involved repeatedly having my head smacked on the roof and not being able to focus on the instruments, and the second departing the US when cabin crew ordered everyone to pour their hot drinks on the carpet before they and their trollies (and a couple of halfwits who thought they were too important to weat seatbelts) got slapped between roof and floor a few times with some minor bone breakage.