"Extreme" Turbulence

[jabba the hut]

Last night, for the first time in my career, I heard a report of Extreme Turbulence on the North Atlantic. It was forecast as "Severe to Extreme" in Gander Sigmet Uniform 1 and reported as "Extreme" by an Airbus A333 at N58 W 030 at 0200z.

I have to ask, was the ride really that bad in that area? Where you in that Airbus? Was anyone hurt? Was your aircraft damaged?

Just wondering. The definition of "Extreme" is pretty scary.

[fantom]

Was waiting to take a 330 back over the ocean but, after the report of 'severe' on the east-bound sector, they needed to download the FDR and send to Airbus to see of there might have been structural damage.

It was OK though and we went.

[Bearcat]

Extreme= structural damage in my little world

[BOAC]

I'd go along with 'potential for' structural damage, Bear.

From agreed met definitions:

Severe Turbulence:

Abrupt changes in aircraft attitude and/or height: the aircraft may be out of control for short periods. Air–speed variations are usually large. Changes in accelerometer readings of greater than 1.0 g occur at the aircraft's centre of gravity. Occupants are forced violently against seat belts. There is difficulty in walking. Loose objects are tossed about.

Extreme - worse than that, up to wings coming off, when reporting normally ceases.:)

[Agaricus bisporus]

Can't speak for intercontinental routes but in Europe turbulence reports are usually treated in a similar way to a Doctor hearing a patients alcohol consumption. They need factoring by two to get an accurate figure, downwards in the case of turbulence.

[jabba the hut]

Thanks for the replies guys. I've been crossing the pond twice a week now for 20 years and in my opinion February is always the worst month for CAT.

I'd like to get to the bottom of that "Extreme" report though. Was it forecast? and then reported, or the other way round. In fact, I would only expect extreme turbulence inside a cu-nim, but we don't go there do we?

Even "Severe" is over-reported. Very few pilots have ever been out of control in turbulence. Sometimes I wish though, that our companies would route us round the worst stuff-even at the cost of a few extra bucks on the fuel bill.

Cheers All

[AtomKraft]

I've had one encounter that we reported as 'severe' in about 11000 hrs of flying.

A/c climbed about 1000' then descended about 5000'. We couln't stop it doing either of these excursions.

Speed varied from way over Mmo- at flight idle-and climbing :uhoh:
to, stick shaker -while at full power and descending. :uhoh::uhoh:

All the while getting shaken :mad:

Lucky we'd been warned and had a chance to get the cabin secured. One of the most alarming things experienced so far.

It was a rotor over the Pyrennees btw. Strong northerly jetstream.

[con-pilot]

I've had one encounter that we reported as 'severe' in about 11000 hrs of flying.

A/c climbed about 1000' then descended about 5000'. We couln't stop it doing either of these excursions.

Speed varied from way over Mmo- at flight idle-and climbing
to, stick shaker -while at full power and descending.

All the while getting shaken


Had the same thing happen to me over the middle of the US, no mountains, just flat farm fields, in completely clear weather in a 727.

But we had no warning at all, it just hit us and it was like flying into a brick wall. We told ATC that we were starting an immediate descent and then we climbed about three thousand feet at idle power. It only lasted about three or four minutes, but it seemed like an hour.

One guard in the cabin received a broken ankle when he was thrown up into the air, hit the headliner with his head and then landed wrong breaking the ankle. None of the 'passengers' were injured as they had to wear their seat belts at all times.

When we finally stopped the climb, we descended to FL 270 and got out of the turbulence. I don't know if we descended under it or just flew out of it.

So that was my first and only report of extreme or properly stated Severe turbulence in my 21,000 hours of flying. As there were a few times I had no control over the aircraft while we were in the turbulence.

After landing that night I was still curious as to what could have caused this turbulence, so I pulled up the upper wind charts and at the time of the incident, the jet stream had a sharp turn back to the west and then back to the east where we had encountered the turbulence. It made a kind of S turn and we got caught in it.

[grounded27]

Usually in these circumstances most airlines report via ACARS the event and often the DFDR is pulled. Often if it can be confirmed as to violated the aircraft's G-limit by ACARS, flight will continue. If in question there are several levels of inspection required and the FDR is pulled to confirm.