More severe turbulence for Westjet


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Apparently a Westjet flight flew over the top of a massive thunderstorm at FL390 just east of YWG a few nights ago and reported severe turbulence with the inability to maintain airspeed or altitude. The controller was heard to reply that no other aircraft had gone along that route for more than 2 hours - everyone else chose to deviate. Can anybody provide some detail?

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Guest rattler

Not being a pilot but curious. If everyone else had chosen to deviate in the previous 2 hours because of the conditions, surely the controllers would have known and have alerted the Westjet crew to it, or is that not the way it works????

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Not being a pilot but curious.  If everyone else had chosen to deviate in the previous 2 hours because of the conditions, surely the controllers would have known and have alerted the Westjet crew to it, or is that not the way it works????

yup, but the controller does not make the decision.

I have been waiting to see how long it would be before this made the forum circuit.

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Guest ACSideStick

The AC ops manual says you shouldn't try and top a thunderstorm as they can build at rates exceeding the aircrafts climb rate (they can build at well over 4000 fpm). If however, you want to try you are to be at least 5000 higher than the REPORTED top.

The 737NG flies at 41000 which would be only 2000 above and coffin corner is pretty small (no margin for error) at FL410.

Even when you are in the "clear" above, the rapid building creates a bow wave in the clear air which can contain severe turbulance.

I don't think any WJ pilot would knowingly tempt fate in that manner. If this is a true story, and it was intentional, someone needs some additional debriefing.

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Oh, it's definitely true. The aircraft was at FL390 as it crossed the top and by the crew's own statement they were "just above" the tops when they got the E-ticket ride.

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Might have to call bull$hite on this one. We were flying the red eye Saturday night east bound at 390. We did deviate to the north in the area of Red Lake because of the T-storms, but if there was such an incident/condition, I'm sure some sort of message would have been passed along by ATC or by dispatch. The ride was fine. Remember I said might, we didn't hear anything about it though.

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Oh, it's definitely true. The aircraft was at FL390 as it crossed the top and by the crew's own statement they were "just above" the tops when they got the E-ticket ride.

In the first post you said 'apparently'. In the post quoted here you say 'definitely'. Were you actually flying in the area when it happened? Maybe you can give a flight number so we can find more out.

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May or may not be true but..

TROLL ALERT!!!!! laugh.gif

Troll Alert? I'm hurt. Besides, I don't think you can legitimately call someone a troll for looking for information about an incident involving an airline on an airline website.

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Troll Alert? I'm hurt. Besides, I don't think you can legitimately call someone a troll for looking for information about an incident involving an airline on an airline website.

Okay, instead of a hard core troll you are merely troll-ing. Happy?

When, as spinny pointed out, you change your story to elicit response then you are painting yourself into a corner. As I previously stated I don't know whether it happened or not but undoubtedly it will come out.

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Okay, instead of a hard core troll you are merely troll-ing. Happy?

When, as spinny pointed out, you change your story to elicit response then you are painting yourself into a corner. As I previously stated I don't know whether it happened or not but undoubtedly it will come out.

I have not changed my story. In my first post I said "apparently" because I was not in the Westjet flightdeck when it happened. I can, however, say that it definitely happened because I was on frequency to hear it.

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Okay, instead of a hard core troll you are merely troll-ing. Happy?

When, as spinny pointed out, you change your story to elicit response then you are painting yourself into a corner. As I previously stated I don't know whether it happened or not but undoubtedly it will come out.

Easy there Mav,

Story goes back a couple of weeks.

Everyone else deviating well away from WX, and descending down for a better ride.

Controller asks flight in question two or three times for clarification that they really want to do this. Each time pointing out what everybody else is doing.

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Actually, the incident I'm referring to was a couple of nights ago; Friday, 5th. I don't know what AIP is referring to, is that yet another incident? Starting to look like a pattern.

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Actually, the incident I'm referring to was a couple of nights ago; Friday, 5th. I don't know what AIP is referring to, is that yet another incident? Starting to look like a pattern.

Yes one I was referring to was at least 10 days ago.

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Boy this is a great thread. Next time I hear someone getting a bad ride I'll be sure to post it here. (sarcasm)  rolleyes.gif

Pivot: Are you a pilot? Do you know the definition of severe turbulence? This is from the AIM;

SEVERE

Turbulence that causes large, abrupt changes in altitude and/or

attitude. It usually causes large variations in indicated airspeed.

Aircraft may be momentarily out of control.

Report as “Severe Turbulence”.

Occupants are forced violently

against seat belts or shoulder straps.

Unsecured objects are tossed about.

Food service and walking impossible.

Would you want to be in this aircraft, at FL390, at night, above a thunderstorm experiencing severe turbulence? Not for me, thanks. Plus, if you had heard the pilot's voice on the radio, you would know that he wasn't enjoying the experience either.

So, obviously with the benefit of hindsight, we see that the decision to fly over the top was wrong. I'm not trying to stake out any high ground as I've certainly made my share of bad decisions but my hope is that some Westjet person might find out the reasoning behind this decision and the rest of us could learn something. I would very much like to know what the pilot saw, or reasoned or considered that made this seem like a prudent and conservative course of action because some day I might be faced with the same situation.

If this doesn't interest you maybe you should just not bother reading the thread.

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The AC ops manual says you shouldn't try and top a thunderstorm as they can build at rates exceeding the aircrafts climb rate (they can build at well over 4000 fpm).  If however, you want to try you are to be at least 5000 higher than the REPORTED top.

The 737NG flies at 41000 which would be only 2000 above and coffin corner is pretty small (no margin for error) at FL410.

Even when you are in the "clear" above, the rapid building creates a bow wave in the clear air which can contain severe turbulance.

I don't think any WJ pilot would knowingly tempt fate in that manner. If this is a true story, and it was intentional, someone needs some additional debriefing.

"The 737NG flies at 41000 which would be only 2000 above and coffin corner is pretty small (no margin for error) at FL410."

Not meaning to be picky, but for our non pilot members out there the coffin corner (speed buffer between high speed and low speed buffet) can be pretty small at any high altitude if your heavy enough. This is the reason we sometimes wait before climbing to a higher altitude or "step climb". We must first reduce our weight by fuel consumption. So, yes, at any given weight the margin is tighter the higher you are. The statement "no margin for error at FL410" is quite misleading as we will not climb to FL410 or any other altitude until our weight and the atmospheric conditions allow us an "adequate margin for error". So we don't fly at FL410 until we have the same margin that we would require prior to climbing to any other high altitude. This is our policy at WestJet. The 737NG is quite comfortable at FL410 so we don't know that this crew had "no margin for error" at FL410.

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Guest ACSideStick

Arctic Ace re The statement

"no margin for error at FL410" is quite misleading as we will not climb to FL410 or any other altitude until our weight and the atmospheric conditions allow us an "adequate margin for error". So we don't fly at FL410 until we have the same margin that we would require prior to climbing to any other high altitude. This is our policy at WestJet. The 737NG is quite comfortable at FL410 so we don't know that this crew had "no margin for error" at FL410"

If the two mentioned were unable to maintain altitude at 410 because they were overflying a thunderstorm (atmospheric conditions as you put it above) then I guess the margin of error wasn't enough, was it?

Why not just say, that "they were off the reservation and operating outside of WJ policy."

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