Turbulence vs Computer glitch
 

If, as some posters are suggesting, this incident was caused by a computer failure, this would imply that the “violent” roll reversals were caused by movement of the control surfaces. Although it is not possible to know how violent these reversals were, anecdotal evidence suggests that they were well above that which is possible to induce via the control surfaces. This would support the hypothesis that this incident was initiated by some sort of turbulence related upset.

CBC News this evening is reporting that investigators are now looking into the possibility that wake turbulence was to blame.

Dave F.

I heard from a friend that a UA aircraft's turbulence caused it.

CBC mentioned a UA flight was close by..........

Dave F.

Too much bullsh1t, whenever this kind of turbulence happens. it is some kind of "clear air turbulence" or anything else but the crew error.
The 9o % chance is that the radar was u/s or the crew did not have radar in proper setting or did not even know how to use it properly.

Green Guard,

That's a stupid comment you made about the crew not having the radar on. An even stupider comment is that you insinuate that they may not even know how to use it.

The aircraft hit clear air turbulence at 36,500 feet during daylight hours. The CAT may have been caused by a meterological event or by the wake turbulence from a passing aircraft.

Radar is used to detect thunderstorms. I would hazard a guess that there are very few thunderstorms in Canada in January. As I type this, the temperature outside my house is a balmy -12 degrees C. Not a lot of thunderstorms develop in these temperatures. I was flying over the Rockies the same day that Air Canada had it's jet upset. There wasn't any reason to have the weather radar on.

You show your ignorance by insinuating that this crew should have had their weather radar on or that they may not have even known how to use it.

Sir, you owe this crew an apology.

Ex-beagle

I hope and pray that you are right and I that I was wrong !
The time must tell the truth.

Did the turbulence suffer any damage? :eek:

Well if you read the article, it said the turbulence went to one of the hospitals and suffered some soft tissue problems. :}

During the 18-second duration of the event, heading varied from 065ºM to 086ºM. The captain reacted to the rolls with a total of nine sidestick roll inputs, accompanied by coordinated rudder pedal deflections. Five sidestick inputs were to full travel of 20º. Seven successive rudder pedal inputs were made, with six cyclic reversals from left to right. Rudder deflection followed pedal inputs with maximum deflection of 6º left and 7º right.



Rudder input?

Clear Air Turbulence
 

India Four Two shows a splendid grasp of Canadian geography, illustrated by his photograph of the Livingstone Range as seen from Cowley Airport. The glider pilots in the photo will be well acquainted with the properties of mountain lee wave which can smoothly elevate the glider to over 36,000 feet - or nearly rip your wings off in the rotor that lurks in the curlover! All of which can be exacerbated by jet streams flowing in contrary directions in a boundary layer. Although wave is often marked by lenticular clouds, if the air is dry they do not alway appear.

I believe this phenomenon does not necessarily show on radar. which should warn of the even more exciting conditions to be found in a cu nimbus..

69 Rooster

Thats weird. Most folk, including me, the very LAST thing you'd do is slam the controls about if in CAT.

Baffling. That action on the controls could cause an upset without any input from weather.

This wasn't your run of the mill CAT encounter. This was an entry into the wake of a B747 which caused a significant roll when the aircraft was otherwise flying in smooth air. The startle factor in such an event is significant and the urge to make a correction would be difficult to ignore.

IMHO rudder inputs are only necessary in the following cases:
1. Engine failures/fires/etc
2. crosswind takeoff's and landings
3. taxiing on a long, straight taxi track and thereby freeing your hand from the tiller to empty your coffee cup.

Hmm... I was under the impression that the whole Airbus design philosophy was precisely to protect pilots against themselves. This is a serious breach IMHO.

If I may make a comment on this issue:
As a frequent long distance traveller I have come to believe that the issue of the seat belt sign could be handled better by crew.
It would help if the crew could give some notice of imminent turbulence when possible.
It is quite annoying to make a dash back to your seat only to find that it is 10 min or more before the first bump. People get used to this delay and factor this into their decision to sit down and belt up.

It sometimes seems to me that the crew forget to turn the sign off.
I have often experienced that the sign goes on, followed by a slight bump and then an absolutely smooth ride for an hour or more with the light still on.
My worst experience was an AF flight across Africa with the light on for close to 3 hours and no turbulence worth mentioning.
To me it is inexplicable, especially when you are sitting there with your legs and eyes crossed.
If there is a good reason for the long duration, it would be helpful for the crew to say so, estimate how long they expect the light to be on and keep us updated – is it so difficult?
As it is I comply, but I’m quite sceptical of the necessity for it being on so long.

I have no idea how the crew predict CAT, other that from weather predictions or seeing bad weather below, so these comments are made in ignorance. Maybe someone can educate me?

Reminds me of a day dodging CB through Florida going north. Lots of red on the screen, and lots of deviating. Had the FA's secure the cabin and take their seats. Went around stuff for close to an hour with nary a bump. Some pax complained about the lack of service. Should have gone through a cell just to give them their money's worth.


Mostlylurking: Predicting bumps is not a science.