Question regardling turbulance

yomchi

Hello all,

I was just wondering if pilots actually know if they are to experience turbulance in advance? Is there a radar that will tell them?
If so, do the piots generally make a effort to aviod it or do they have to go straight through it?

I ask this because on a recent Ryanair trip, I got up to go to the toilet and while walking down the aisle the plane took such a dip downwards that i felt I was going to float off the floor! The only think I have found was that it could have being avoiding turbulance, or was it just the Ryanair pilot?

Thanks

RoundyMooney

Presumably if the seatbelt sign was off, the aircraft would be above the level at which turbulence would be expected, I'm open to correction on this however.

Pilots do have WX (weather) radar available to them, and you'll often hear warnings over the PA when turbulence is expected, in my experience at least.

HTH

FlutterinBantam

Regarding turbulence,what you experienced was probably CAT= clear air turbulence.

No way of knowing that baby is upon you until you hit it.

Pilots in the same area would always report instances of CAT so those in the area would be aware.

Otherwise they rely on weather radar and meteorological experience.

jmayo

There are Clear Air turbulence forecasts which I think are worked out using both radar and complex algorithms. Also pilots report incidents of turbulence so that following flights can avoid or warn their passengers.

As far as I know you can hit clear air turbulence at over 38,000 and commerical traffic is operating under this so by going high you only avoid lower turbulence.
There are few reasons for air turbulence including:
Mountain wave which can be predicted because the wind direction & speed maybe particularly favourable.
Turbulence can be casued by thunderstorm systems and big multicell systems can reach pretty high altitudes as well.
Wind shear turbulence is pretty dangerous near ground.

You should never go near thunderstorms in small plane because you are asking for trouble.

yomchi

Thanks for the input guys, the seatbelt sign was off alright. So it can be possible for the pilot to make a sound diversion just like that? It was quite a sudden dip. Mind you it ight have felt exaggerated due to the fact that I as standing at the time.

Steyr

You aint hit Turbulence until you hit it in a Cessna 172, i hit it over Lough Corrib in EI-GWY, boy o boy was that a brown pants moment, we dropped a significant altitude too.:eek:

yomchi

can it make you crash?

jmayo

Steyr said ....You aint hit Turbulence until you hit it in a Cessna 172, i hit it over Lough Corrib in EI-GWY, boy o boy was that a brown pants moment

Can't resist this but Steyr are you the one responsible for the water pollution...

Could be just thermal triggered off edge of lake and land?
Are you near mountains at any stage to get ridge lift/sink?

You should try mountain flying, you get some lovely updrafts and of course where there is lift there must be sink. Nothing like getting 10 down, while at full power trying to climb, knowing there is a lot of rock below you and above you. Have to be really careful of rotor around mountains. Also going over passes is interesting because you could be in lift one minute and you could be in sink the next. You have to try to read the wind and fly up side of valley with wind hitting it, cause it is always easier to loose height than gain it.

To answer question on damaging aircraft with turbulence.
The turbulence around big thunderstorms can down an aircraft because the airframe may not be able to handle the stresses if you get too close. The rotor resulting from mountain updrafts/downdrafts can flip an aircraft or overstress the airframe.
Wind shear can down aircraft close to landing and as far as I know has downed jets.
Wind shear may appear like turbulence to passengers not sure if it really fits description here?

The smaller the plane and the bigger the turbulence the more susceptable to damage.
So yes turbulence can be very dangerous to aircraft.

The biggest danger for commerical airline passengers is hitting head on overhead or falling luggae.
Some guy on Asian (Korean or Japanesse) airliner lost his life because he hit is head so hard off overhead storage locker.
So do keep on the seat belt, especially if flying near mountains or in tropics.

RadioRetro

IIRC Ryanair don't go as high as FL 380, something to do with get up to cruising height quick, get down on the ground quick.

What you may have experienced, btw, could have been an air pocket where the air pressure is lower than the surrounding air and the plane drops like a stone until it either hits the bottom of the pocket or the pilot adjusts the controls to fly straight and level again. It can be quite startling with things (and sometimes people) flying up to the cabin ceiling.

yomchi

RadioRetro wrote:

IIRC Ryanair don't go as high as FL 380, something to do with get up to cruising height quick, get down on the ground quick.

What you may have experienced, btw, could have been an air pocket where the air pressure is lower than the surrounding air and the plane drops like a stone until it either hits the bottom of the pocket or the pilot adjusts the controls to fly straight and level again. It can be quite startling with things (and sometimes people) flying up to the cabin ceiling.

I think that pretty much sums it up!
Thanks for all the input.
BTW I came across some information on another forum where a pilot of one of the larger fleets was stating that a plane has never crashd due to turbulance at cruising altitude. INteresting!

Steyr

Jon wrote:

can it make you crash?

Yes it can in extreme cases, we were at about 2,500 and i can only describe it like a punch to the top of the head, the plane just went down a few feet but it was dramatic enough.


And no i did not cause the Pollution i will have you know i shower daily!:D

jmayo

Jon like everything size matters or rather size and strength matters.
Big 747 or fast military jet will take more than Cessna 172.
Then again Cessna 172 would not be up at 35,000 feet.
There have been accidents with large jets down near ground due to wind shear. Also some large aircraft accidents, including 747s, have been listed as having turbulence as possible cause.

yomchi

Thanks jmayo. Are there any pilots here on this forum?

This stuff is fascinating

Steyr

Jon wrote:

Thanks jmayo. Are there any pilots here on this forum?

This stuff is fascinating

a few of my mates are, one is a prof pilot, I am not a pilot but do go up with one of the lads from GFC when asked, great fun in the Cessna's!:D

Darren

I was going to the Ireland v Oz game in Australia 2003 when we hit some wake turbulence between Singapoe and Melbourne on a BA744. The plane took a good few jumps, the pilot even came on the PA to tell everyone what happened ( That's a first for me on BA.) He said that we had crossed the wake of another aircraft. Any one know how long this wake turbulence lasts for, I've already got a pretty good idea that it would depend on size and speed of the aircraft.

FlutterinBantam

Are you SURE thats what he said???

Seems very strange to me.

Darren

Yep, I'm sure. He even remarked on how it should not happen. The flight no was BA17 and guessing here, it was about Oct 30/31st 2003.

oscarBravo

The magnitude of wake vortices depends mostly on the weight of the aircraft that creates it. They descend slowly, dissipating as they descend. In theory they don't dissipate completely until they reach the ground, but (if formed at cruise altitude) they're pretty much infinitesimal at that point.

Steyr

Darren wrote:

on a BA744.

Dont you mean a 747?

oscarBravo

744 is shorthand for 747-400.

damo

Yeah turbulence is pretty crazy in small planes....i was flying a cherokee over in florida, it was one of those crazy hot days over there and the thermals were absolutely blasting the plane, it was nearly uncontrollable, and on top of it i was diverting 70 miles back to base because i was running solely on the electric fuel pump, cos the mechanical one died on me! nervous moments :eek:

highlydebased

RadioRetro wrote:

IIRC Ryanair don't go as high as FL 380, something to do with get up to cruising height quick, get down on the ground quick.

.

Incorrect. Ryanair regularly go upto FL400, especially on the longer flights from the Canaries/Southern Spain. They might settle at 350 etc initially, but once enough fuel is burned they climb higher. Higher altitudes also result in less fuel being burned.

On some flights- Especially Ireland-UK there are level caps in place by London/Manchester ATC. This is generally for traffic etc. Nothing to do with getting up and down quickly

electric69

usually they try and avoid large thunderstorms at all costs,but if for some reason, e.g non clearance from ATC, different countries airpsace, they have to fly straight through them.
What happens in thunderstorms (without getting into to much detail) is at the dissipating stage there are strong winds coming down from above, sometimes 50kts or more, and when these hit the plane/helicopter the ship quite simply drops.Pending on the size of the ship they will have different effects.Most large fixed wings will only drop (or shoot up,if during the cumulus stage of the storm) a couple of hundred ft, but smaller fixed wings and more significantly helicopters usually cant cope with the downwinds and dont have the power to fight against these winds and quite simply drop.
Thats the reason why you arent supposed to fly within 25 nautical miles of a thunderstorm!


The pilot who came on and announced that the turbelence was due to wake turbelence was completly to blame for that.Theres no way that he should have been close enough to the other ship for that to happen.

All smaller fixed winged and helicopters are supposed to land upwind and after the landing spot of larger planes to avoid wake turbulence and have a nice comfortable landing.