I just read thru the Air France thread and have a question about the rules the 121 guys use for TS avoidence? The reason I ask is from past observations. I remember last summer going north thru the midwest near STL when a UPS plane in cruise punched thru a top of a pretty good sized cell. The pilot reported to center "we just had mod to severe turb I think we flew thru a top". I have noticed also while turning around storms and wondering if I am far enough away only to see an airliner pop up on TCAS 10 miles closer than I am. (look at the pic in the airfrance thread)

A few weeks ago there was a solid line of40k and 50k top thunderstorms across the country between me and the destanation ,,we just sat it out.(we have the option) But I look at flight aware and planes are still going thru the line. I wonder if I am over cautious, (ie, candy a%$ or insert your own name) Do you guys have the option of saying were going to wait, or is it "we have to go so lets find a way to get it done"

 

You never wait. You just leave. You fly until you find a hole you like, and feel good about, no matter how far. If it was to run you short on gas you would divert.

 

However put a doctor in a Bonanza and he'll head for the heart of the storm every time...........

 

I have to admit, I do not know any FARs regarding flight in areas of convective activity. However, my company uses these rules ...

TAKEOFF / LANDING:
TS within 15NM of intended flight path, CA should use another departure/arrival or runway, consider delaying takeoff or landing, and use all available information (PIREP, tower, ground/airborne radar, winds, observations, etc.).

TS within 3NM of intended flight path, takeoff / landing is not permitted.

ENROUTE: (this has been reduced down, but the CA has a lot of leeway).
Avoid flight under the anvil, or flight into the cirrus or cirrostratus cloud layers downwind from a thunderstorm. Everything else is a bunch of suggestions and considerations (for example, you should deviate to the upwind side of the storms, CAUTION, hail can be encountered up to 20NM away from a cell .. etc.)

I typically use the USAF rules of cell avoidance. Above FL230, avoid cells by 20 NM, below FL230, avoid cells by 10 NM. That usually keeps you well clear of anything; however, sometimes you have to thread the needle between two storms. In that case, if I can't go around them, fly between them but stay much closer to the downwind storm.

 

Here is a .pdf copy of an article from the latest Business & Commercial Aviation issue titled "Using Weather Radar to Counter FL Cells".

Nothing earth shattering, but its well worth the read...

 

I'll take a line of thunderstorms any day over most types of inclement weather. A line of thunderstorms is the most predictable type of weather you can ask for. It's going to be smooth upwind from them (usually), it is usually smooth even when you are close to the well developed ones and you will have improved viability (usually) unless they are embedded. Even though there may be a line of TH's they rarely join together to make a true line. And there is never a question if you should fly under them or not. A level 5 thunderstorm can way 450 thousand tons. When it decides to come down... well you dont want to be there in an airplane. Much like the defensive line of the Chiefs, if you are patient and look for the right clues they WILL let you through without having to go over the top.

 

Just skirt around the backside....

 

Never think that you are over cautious in my opinion. I have delayed a flight due to thunderstorms before. That was also when i was first a captain. In the 3 years since i now know what my limits are and looking back, I would have left with out any delay. But that day, it was the best decision to wait in my opinion.

 

From ALPA's magazine:


It's easy, just follow the guy in front, and if it is UPS and they're complaining, stay even further away!

 

Dispatcher!!!!