View Full Version : A question about CB's
111boy
9th Jun 2010, 14:30
Last night there were 2 large Thunder Storms cells over Prague. About 15 miles apart, isolated really, no other clouds above about FL35. They were very active electrically and went above us at our cruise 380. We opted to go round them, upwind giving them a good 10 miles. Whilst flying past them another aircraft at FL360 went between them.
I didn't fancy doing that, being a coward, and was interested to know what anyone else thought about doing that really?
thanks
Pilot Positive
9th Jun 2010, 16:28
Probably best to avoid completely if you are unsure by using you a mixture of WX radar to identify the areas of heavy precipitation return and by advising ATC of upwind track corrections to avoid. :cool:
If you do have to fly between them and its unavoidable put the seatbelts sign on, advise cabin crew and maybe make a PA to pax as an extra precaution.
PP
ggofpac
9th Jun 2010, 16:34
i'd avoid them even if that means way off track.
cortilla
9th Jun 2010, 21:55
Talking about europe where they are avoidable (i.e. not the ITCZ) we have an SOP that at higher levels we must avoid all CB's by atleast 20 miles. In europe it is relatively easy as most CB's are ISOL so can skirt around them. So going inbetween 2 cb's that are 15 miles apart at upper levels. No chance.
frogone
9th Jun 2010, 23:07
If there's blue sky available personally I just use it and go around them, much easier on pax, pilot and plane.
I had a similar scenario near Alicante the other week, about 8 CBs around so I turned left about 30 degrees for about 80nm and went around them, only to hear a colleague overtaking me driving right through them (ones that were providing just amber returns). I just don't see the point in taking any chances if you don't have to, I think it's kinda negligent to drive into developing CBs. Just my 2 cents. I can't comment on the ITCZ :\
Anybody thinking of picking their way at altitude amongst storm tops would be well advised to acquaint themselves with the ARC report 1248 of Ann Burns from 1973, available at http://naca.central.cranfield.ac.uk/reports/arc/cp/1248.pdf
Amongst other things, it suggests that you can get slammed without much warning.
PBL
Pilot Positive
10th Jun 2010, 10:46
Good report PBL, where did you find it?
Perhaps a more extreme example of what could happen when going through CB/TS is the Air France Airbus lost over the Atlantic where all souls were lost (yes I appreciate that it didnt happen in Europe and that its hasnt been officially confirmed as a contributing factor to the accident) ...if you can avoid, do so. :ok:
Good report PBL, where did you find it?
An aerodynamicist with whom I work put me on to it. I understand the report is quite well-known amongst British aerodynamicists, because of the light it sheds on how appropriate certification requirements were/are.
There is another set of older data from the U.S. about what happens *inside* thunderstorms at http://naca.central.cranfield.ac.uk/reports/1956/naca-report-1285.pdf
This one is over half a century old!
PBL