Delta Weather Procedures

[Le Pilote]

Well it's going to be a long, bumpy T-storm season. Starting already! But hey at least it's not snowing.

 

[Flyer7SA]

I'm just curious, what exactly can an aircraft handle, thunderstorm wise? Obviously flown at Va, anything from a 172 to a transport category aircraft.

That really depends upon the aircraft. The older series Lears had 6 spars per wing. The wing loading was tested to over 11 Gs without failing, though it was certified much less. The pressure vessel was tested to Apollo standards which was 21 PSI differential before failure, though it was certified only to max 8.9 psi. This type of engineering is just not around anymore. I wouldn't go far to say that newer aircraft are inferior in any way, just that you might not even bat an eye at taking an aircraft such as an earlier Lear or Sabre into heavy Wx, whereas a KingAir or RJ, you may think twice about it (especially if you have Pax riding in back, rather than a drunk businessman who is just going to barf in his briefcase because he's worried that you'll charge his company for the cleanup).

As for Va, well, that's also being "redefined" . American Flight 587 was well below Va when the abrubt control force caused a structural failure. Our "classic" definition of Va is the speed at below which an aircraft will stall before any structural damage occurs. Perhaps that definition needs to be looked at again.

~FLyer7SA

 

[FN FAL]

As for Va, well, that's also being "redefined" . American Flight 587 was well below Va when the abrubt control force caused a structural failure. Our "classic" definition of Va is the speed at below which an aircraft will stall before any structural damage occurs. Perhaps that definition needs to be looked at again.

~FLyer7SA

Why would the definition need to be re-defined? VA protection is guaranteed on a rudder if you are below VA and you make a complete and abrupt control input to the rudder pedal and then let it re-center itself. Stomping on it in one direction all the way to the floor and then stomping on it in the other direction all the way to the floor, exceeds the limits of VA protection. Where is the confusion?

 

[chperplt]

Why would the definition need to be re-defined? VA protection is guaranteed on a rudder if you are below VA and you make a complete and abrupt control input to the rudder pedal and then let it re-center itself

Where is the confusion?

You didn't read the NTSB report on the AA flight, did you? The NTSB specifically calls into question our current definition of VA. They further state that control movement in the manner you describe above below VA can cause a catastrophic event.

 

[learflyer]

I actually flew with a captain who said "Hey, the only thing you have to worry about a thunderstorm is the hail". He made me feel ALOT better! I love these pilots that just launch into tstorms after takeoff and then complain to tower or atc that "we need 20 left or right immediately for wx". You ever think of waiting 5 mins for it to pass?

 

[Goose Egg]

Our "classic" definition of Va is the speed at below which an aircraft will stall before any structural damage occurs. Perhaps that definition needs to be looked at again.

Flying at or below Va will only guarantee the prevention of structural damage if the aircraft is experiencing symmetrical loads. In a thunderstorm, there is no guarantee that loads will be symmetric.

-Goose

 

[satpak77]

I'm just curious, what exactly can an aircraft handle, thunderstorm wise? Obviously flown at Va, anything from a 172 to a transport category aircraft.

Serious T-Storms should be avoided in ANY aircraft. Its the shear and vertical currents that will break an airplane apart, not necessarily (all though these will too...) the horizontal turbulence.

Revisit DAL in DFW in 1985-ish, TWA(?) or Pan Am in New Orleans in 70's, AA at Little Rock in 99(?)

Also observe VA may or may not be the "turbulence penetration speed" in your POH. Whatever the speed is, that is for a brand new airplane, not one flown by 100 freight doggers/CFI's/student pilots/prior owners/etc/etc.

Use your judgement.

My cry-baby puzzy a$$ self avoids all major towering cumulus with tops above 250, and I will deviate BIG TIME (fuel etc, allowing) to stay "VMC" between the clouds. I also prefer my human eyeballs over a radar anyday, altho I couple radar data with stormscope data and attempt to make an educated guess as to storm activity.

Back in my cancelled-check 135 days, we never flew IMC (almost never) thru T-storm areas, we went VFR with flight following and dodged them. At times this meant dropping down LOW LOW to the "highest sector" (or whatever its called, the highest number in that particular quadrant) altitude on the VFR sectional, and dodging rain shafts. Talking to your buddies on 122.85 up ahead also helped. Back then (now?) the only freight dogs with "real radar" were the Show Me or Martinair guys in Caravans. We used their Pireps alot.

later

 

[ATCER]

falcondriver - after watching just about every carrier deal with weather I'll say that they all handle weather very similar. More then once I have seen 2 or 3 A/C "find a hole" and get through the worst of it to get into the airport. I have also had to deal with the guy that tried the same thing and it closed in around him. I notice that 99% of pilots are very conserative enroute but get a little more liberal as they get clsoe to the field. Where they would deviate 30 miles around a buildup enroute, some choose to find a hole to fly through if they are close to their destination.

As for best and worst from my observations... AAL is by far the most conservative. Where everyone goes 10 miles, they go 30. They often are the only ones that deviate. Slight bad rides reported up high... they all file for FL280. Worst... many foreign carriers, especially some of the south american flag carriers. You give them sigmets, airmets, etc. they roger you and stay on the route while everyone is slowing down and deviating.

 

[FlyingSig]

I think this is the oldest thread I've ever seen resurected.... I had been just furloughed for about 2 weeks when I made that post ... 3 years, 2 months later ....


...nevermind, now that I read more threads I see Le Pilot is on a tear.....

 

[Flyer7SA]

I think this is the oldest thread I've ever seen resurected.... I had been just furloughed for about 2 weeks when I made that post ... 3 years, 2 months later ....


...nevermind, now that I read more threads I see Le Pilot is on a tear.....

FlyingSig, you're absolutely right. It is kinda strange how all that time has passed since that thread and somehow I got a reply to it in my inbox and it seems to have started a snowball effect. Someone must have done a search on a word and didn't realize how old the thread was... No matter. Kinda nice to be back on the board again. My how times have changed, eh?

As for bad thunderstorms, we had an exciting afternoon in Wichita. A couple of friends made it in just before the storm (which seemed to die out pretty fast after dark). I had moved from Atlanta to Wichita since I made that post, and I thought that we had some pretty good storms in the south until I moved out here. The Wx out here is full of extremes. In the fall, seriously, watch out for trying to get into ICT on a foggy morning. I drive past the approach end of RWY 19R every day to work and there were some mornings I couldn't see the airport fence 15 feet from the road. I was watching a pretty good light show the other night, listening for sirens and then watching hail accumulate on my deck thinking, I'm glad I'm not up in that - and this was around 11:30PM. We never had hail in ATL that I can remember at night, yet alone very often.

Back on topic, though, sometimes I've chuckled at airlines that deviate WAY out of their way to avoid the slightest bumps or clouds. I shutter to think how my version of "medium chop" must feel to some of those airliner types... Then again, I think that my version of "smooth ride at 330" must be a harrowing experience to some . I've learned to gage my pireps according to the audience listening. Perhaps one pilot's "light chop" is another's "moderate turbulence". -Hard to say.

Livin' the dream,
Flyer7SA