Thunderstorm Avoidance
Thread Starter
Join Date: May 2000
Location: oz
Posts: 127
Likes: 0
Received 0 Likes
on
0 Posts
Thunderstorm Avoidance
Am interested in hearing on how and what methords people use to determine what distance to go off track and any useful tips when avoiding thunderstorm situations.
Join Date: Nov 2001
Location: NY
Posts: 277
Likes: 0
Received 0 Likes
on
0 Posts
just don't go through 'em. The turbulence around them generally isn't any worse than the convective stuff you get off the desert. I've been sitting with one wing in the cloud trying to stay VFR and the ride isn't particullary bad or scary....and most of those were level 5 TS's. I popped under a roll cloud once...wouldn't recommend doing that...but the NT guys could probably give ya a few tips.
When you're feeling brave you can get an extra 30-40 knots on the bowwave off the bottom of a tropical CB....just like surfing 
Just don;t let the lightning scare you!
Seriously though - just look at the way the storm has formed and thing what the wind is doing. Watch the virga, watch the wind effects on the ground. That will tell you how far to stay away from it. Sometimes you have no choice but to get bloody close!
CS
Just don;t let the lightning scare you!
Seriously though - just look at the way the storm has formed and thing what the wind is doing. Watch the virga, watch the wind effects on the ground. That will tell you how far to stay away from it. Sometimes you have no choice but to get bloody close!
CS
Guest
Posts: n/a
There are probably as many techniques and ideas on this as there are pilots, some points that come to mind are;
-Stay out of them (CB,s), especially if Magenta is painting, otherwise expect a memorable ride. Im tempted to say they tend to be more active around the ITCZ & Sub-Continent (and they are) but in reality if the conditions are suitable they can all pack a good punch regardless of Latitude.
-Take note of the Met Brief (assume its accurate) if possible re-file another route to avoid concentrated areas of CB activity.
-Keep your eyes open,(inside & outside the cockpit) especially at nite, there always seems to be a skinny cell sitting just
under/obscured by the trk line that will kick your A... when you least expect.
-Know your wx Radar system, Read the handbook but also have a play (with the Radar!) in clear air. Tilt, Cal, Range, Ident, etc. you will find settings that work for your operation. Wx Radars seem to vary in accuracy and can have thier own personality.
-Try and pass, up-wind of the cell to reduce Turb,
-Begin avoidance early, Try not to find yourself in a situation where the CB is closer than your turn radius!. Some companys have SOP's on lat dist from cells. It is fair to say you can " just miss them" but not that prudent, 3- 5 miles should be safe, depending on how active they are, you may want more
-Try and avoid flying just over CB's, especially building ones, often there is CAT lurking there. conversely avoid flying under
"overhangs" these may contain nasty surprises , freezing rain etc
-If you find yourself in a situation where you cant avoid penetrating a line of CB's, (and sooner or later you will) have an awareness of your Buffet margins, Turb pen speeds, use of a/c systems, Ignition, A/T , A/P, EAI/WAI etc, make sure you have full avail perf if or when you req it.
when in areas of active wx I tend to leave the hdg select at Max AOB so I can turn quickly if required, you can always back off the angle later, Yeh I know some people Bitch about this down the back, but they will Bitch more if you run into a CB.
-I avoid large/excessive deviations from TRK (I would consider this >40- 50nm) I prefer to prepare the cabin, batten down the hatches and find a suitable route, If the atmosphere is that unstable going 100nm off trk will probably just turn up more wx! so what do you do? go another 100nm, next thing your diverting due insuff fuel
-Advise the cabin, dont just tell them "theres a bit turb ahead" if warranted TELL them to stow the Galley and take their seats immediatley, ensure pax remain securely seated until the all-clear. if its a real rough ride advise your maint people.
-Lastly tell ATC if your deviating around wx, otherwise you may be in for another rough ride from the duty supervisor, then the boss, if ATC are slow coming up with a CLR theres a procedure in Jepp to follow
Im sure theres more!
-Stay out of them (CB,s), especially if Magenta is painting, otherwise expect a memorable ride. Im tempted to say they tend to be more active around the ITCZ & Sub-Continent (and they are) but in reality if the conditions are suitable they can all pack a good punch regardless of Latitude.
-Take note of the Met Brief (assume its accurate) if possible re-file another route to avoid concentrated areas of CB activity.
-Keep your eyes open,(inside & outside the cockpit) especially at nite, there always seems to be a skinny cell sitting just
under/obscured by the trk line that will kick your A... when you least expect.
-Know your wx Radar system, Read the handbook but also have a play (with the Radar!) in clear air. Tilt, Cal, Range, Ident, etc. you will find settings that work for your operation. Wx Radars seem to vary in accuracy and can have thier own personality.
-Try and pass, up-wind of the cell to reduce Turb,
-Begin avoidance early, Try not to find yourself in a situation where the CB is closer than your turn radius!. Some companys have SOP's on lat dist from cells. It is fair to say you can " just miss them" but not that prudent, 3- 5 miles should be safe, depending on how active they are, you may want more
-Try and avoid flying just over CB's, especially building ones, often there is CAT lurking there. conversely avoid flying under
"overhangs" these may contain nasty surprises , freezing rain etc
-If you find yourself in a situation where you cant avoid penetrating a line of CB's, (and sooner or later you will) have an awareness of your Buffet margins, Turb pen speeds, use of a/c systems, Ignition, A/T , A/P, EAI/WAI etc, make sure you have full avail perf if or when you req it.
when in areas of active wx I tend to leave the hdg select at Max AOB so I can turn quickly if required, you can always back off the angle later, Yeh I know some people Bitch about this down the back, but they will Bitch more if you run into a CB.
-I avoid large/excessive deviations from TRK (I would consider this >40- 50nm) I prefer to prepare the cabin, batten down the hatches and find a suitable route, If the atmosphere is that unstable going 100nm off trk will probably just turn up more wx! so what do you do? go another 100nm, next thing your diverting due insuff fuel
-Advise the cabin, dont just tell them "theres a bit turb ahead" if warranted TELL them to stow the Galley and take their seats immediatley, ensure pax remain securely seated until the all-clear. if its a real rough ride advise your maint people.
-Lastly tell ATC if your deviating around wx, otherwise you may be in for another rough ride from the duty supervisor, then the boss, if ATC are slow coming up with a CLR theres a procedure in Jepp to follow
Im sure theres more!
Join Date: Jun 2000
Location: Melbourne, Victoria, Australia
Posts: 71
Likes: 0
Received 0 Likes
on
0 Posts
In a non-radar environment, weather diversions probably create more work for ATC than anything else. To help ATC help you it may be worth considering the following.
- There will usually be some delay in provision of clearance to divert off track from ATC, this is caused by the requirement to coordinate with surrounding units and assess the impact of the diversion on separation. If you leave your request until the last possible moment you may not get clearance in time.
- Many of the separation standards that ATC use outside radar coverage are dependant on aircraft tracking directly to or from a known point, whilst an aircraft is actually flying around CBs we have very limited options. Even if you cant regain track once you are established tracking direct to a waypoint or NAVAID we have more to work with.
- I understand the magnitude of a diversion is initially a guestimate, but if it becomes clear that you will not need all of the 40nm or so off track that you initially request, tell us - generally the larger the requested diversion the more work for ATC. The way ATC separate off radar is basically to protect a "sausage" around an aircrafts track, dimensions determined by RNAV capability and ground based NAVAIDS. For approved INS the dimensions are 14nm either side of track, if that aircraft diverts 40nm left of track, this is just added to the appropriate side, so the new sausage would be 54nm left and 14nm right of track. Obviously large diversions can take up a lot of airspace, If you ask for fifty and it turns out twenty will do, please tell us!
- If you are issued a clearance to divert and later report regaining track, ATC will consider the clearance to divert is now void, they may get a nasty surprise if you divert again.
Hope this helps.
- There will usually be some delay in provision of clearance to divert off track from ATC, this is caused by the requirement to coordinate with surrounding units and assess the impact of the diversion on separation. If you leave your request until the last possible moment you may not get clearance in time.
- Many of the separation standards that ATC use outside radar coverage are dependant on aircraft tracking directly to or from a known point, whilst an aircraft is actually flying around CBs we have very limited options. Even if you cant regain track once you are established tracking direct to a waypoint or NAVAID we have more to work with.
- I understand the magnitude of a diversion is initially a guestimate, but if it becomes clear that you will not need all of the 40nm or so off track that you initially request, tell us - generally the larger the requested diversion the more work for ATC. The way ATC separate off radar is basically to protect a "sausage" around an aircrafts track, dimensions determined by RNAV capability and ground based NAVAIDS. For approved INS the dimensions are 14nm either side of track, if that aircraft diverts 40nm left of track, this is just added to the appropriate side, so the new sausage would be 54nm left and 14nm right of track. Obviously large diversions can take up a lot of airspace, If you ask for fifty and it turns out twenty will do, please tell us!
- If you are issued a clearance to divert and later report regaining track, ATC will consider the clearance to divert is now void, they may get a nasty surprise if you divert again.
Hope this helps.
Join Date: Nov 2002
Location: Brisvegas
Posts: 243
Likes: 0
Received 0 Likes
on
0 Posts
Some interesting points there WWT. Good to get an ATCO's perspective. Aerocom as sated there are plenty of different methods to determine a safe distance. I was always taught (and still teach today) that for every 10,000 feet of CB, add 10 miles for off-track avoidance. E.G. 10,00 feet divert 10 miles off track, 20,000 feet 20 miles off track, 30,000 feet, 30 miles off track etc.
The biggest and most powerful thunderstoms I have witnessed anywhere in the world are right here in Oz. Particularly around the Kimberly region of W.A. If you draw a line from Syd across Oz to Perth, you will find some of the best CB activity anywhere. Whilst even the smallest CB should be avoided at all costs, the behemoths in the Northern half of Oz require the utmost respect.
Scouting around the outskirts of ANY CB with your wingtip in the cloud is an accident waiting to happen. Contrary to what has been previously stated, I was in a jet that rolled through 60 degrees and lost 400 feet in "clear air" whilst not giving a CB a wide enough birth. By radar we were more than 15 miles from the cell. I have never been that close since. Maybe an over reaction but I have never been caught out using the above technique.
Use whatever works mate, just don't get too close.
The biggest and most powerful thunderstoms I have witnessed anywhere in the world are right here in Oz. Particularly around the Kimberly region of W.A. If you draw a line from Syd across Oz to Perth, you will find some of the best CB activity anywhere. Whilst even the smallest CB should be avoided at all costs, the behemoths in the Northern half of Oz require the utmost respect.
Scouting around the outskirts of ANY CB with your wingtip in the cloud is an accident waiting to happen. Contrary to what has been previously stated, I was in a jet that rolled through 60 degrees and lost 400 feet in "clear air" whilst not giving a CB a wide enough birth. By radar we were more than 15 miles from the cell. I have never been that close since. Maybe an over reaction but I have never been caught out using the above technique.
Use whatever works mate, just don't get too close.
Guest
Posts: n/a
Radar tip. When cruising at high altitude IMC/night ensure the radar gain control is set at MAX position rather than AUTO or CAL.
It gives you a better chance to pick up weak reflections from the dry area in the CB anvil which will not normally paint on radar in auto gain. Under these conditions even the tiniest echo picked up on MAX gain is indicative of a towering CB top well above your cruise altitude. Read the Pilot's Guide handbooks which each radar manufacturer publishes. See your local radar manufacturer's agent in most capital cities.
It gives you a better chance to pick up weak reflections from the dry area in the CB anvil which will not normally paint on radar in auto gain. Under these conditions even the tiniest echo picked up on MAX gain is indicative of a towering CB top well above your cruise altitude. Read the Pilot's Guide handbooks which each radar manufacturer publishes. See your local radar manufacturer's agent in most capital cities.
Moderate, Modest & Mild.
How interesting. As Sperm Bank wrote, "The biggest and most powerful thunderstoms I have witnessed anywhere in the world are right here in Oz.", I too would concur with that.
The Cb's in the tropics, whilst appearing similar, don't pack the same wallop.
Personally I would totally ignore druglord's comments, because as much as he may have been lucky so far, there have been several recorded instances of aircraft being totally destroyed by straying too close to a Cb.
The recommendation I had beaten into me as a young Ansett pilot, several decades ago, has proven fairly reliable - minimum lateral separation of 10nm from the nearest part of the f@cker when OAT is above freezing level, and 20nm lateral avoidance when OAT is below freezing.
Spermie's probably erred on the safe side, with his 10nm/10k of height, as I have often seen Cb's up to 60,000' in Oz.
Avoid flying under the overhang (the longer part of the anvil top), and try to fly upwind (vs downwind) when diverting around them.
If, at some stage you HAVE to fly through a line of them, avoid "hooks" (on radar returns) and areas where 2 of the mothers are close together. When using radar, 3 on the "Gain" seems about as sensitive as you would want. Some of the younger guys want to use "Max", and then find themselves wanting to divert around rain showers.
If you do get caught in one, fly pitch...don't go chasing airspeed.
Above all - contrary to other advice - avoid going too near them, esp. the young developing ones (usually from 10 or 11am, through to around 2 or 3pm), these are the most active. Dissipating/mature/decaying Cb's pack less of a whack, but probably enough to do some serious structural damage if you get too intimately involved!!
The Cb's in the tropics, whilst appearing similar, don't pack the same wallop.
Personally I would totally ignore druglord's comments, because as much as he may have been lucky so far, there have been several recorded instances of aircraft being totally destroyed by straying too close to a Cb.
The recommendation I had beaten into me as a young Ansett pilot, several decades ago, has proven fairly reliable - minimum lateral separation of 10nm from the nearest part of the f@cker when OAT is above freezing level, and 20nm lateral avoidance when OAT is below freezing.
Spermie's probably erred on the safe side, with his 10nm/10k of height, as I have often seen Cb's up to 60,000' in Oz.
Avoid flying under the overhang (the longer part of the anvil top), and try to fly upwind (vs downwind) when diverting around them.
If, at some stage you HAVE to fly through a line of them, avoid "hooks" (on radar returns) and areas where 2 of the mothers are close together. When using radar, 3 on the "Gain" seems about as sensitive as you would want. Some of the younger guys want to use "Max", and then find themselves wanting to divert around rain showers.
If you do get caught in one, fly pitch...don't go chasing airspeed.
Above all - contrary to other advice - avoid going too near them, esp. the young developing ones (usually from 10 or 11am, through to around 2 or 3pm), these are the most active. Dissipating/mature/decaying Cb's pack less of a whack, but probably enough to do some serious structural damage if you get too intimately involved!!
Last edited by Kaptin M; 27th Oct 2003 at 02:45.
Join Date: Jun 2001
Location: Ozmate
Posts: 376
Likes: 0
Received 0 Likes
on
0 Posts
I agree with Sperm Bank and Kaptin M.
The worst mothers of CB's I have struck anywhere in the world are in Oz.
Particularly avoid anything brewing around Casino, Armidale, Coffs Harbour, Gold Coast, Sunshine Coast or Brisbane !!!!
They can be ferocious (as the last few days have proven).
Best advice is give them a WIDE berth as has been stated.
Don't be tempted to fly over one too closely or between two closely spaced cells.
Treat them with the respect they deserve.
They can BREAK A/C !!!!
Love to watch them though (from a respectable distance of course).
The worst mothers of CB's I have struck anywhere in the world are in Oz.
Particularly avoid anything brewing around Casino, Armidale, Coffs Harbour, Gold Coast, Sunshine Coast or Brisbane !!!!
They can be ferocious (as the last few days have proven).
Best advice is give them a WIDE berth as has been stated.
Don't be tempted to fly over one too closely or between two closely spaced cells.
Treat them with the respect they deserve.
They can BREAK A/C !!!!
Love to watch them though (from a respectable distance of course).
Join Date: Nov 2001
Location: NY
Posts: 277
Likes: 0
Received 0 Likes
on
0 Posts
dittos on the worst TS's being in oz. 10nm and 20nm I'd agree would be ideal, however bush VFR in the wet rarely affords that level of safety.... and bush operators don't like to cease operations for 4 months of the year.
Join Date: Mar 2000
Location: Location Location
Posts: 448
Likes: 0
Received 0 Likes
on
0 Posts
I agree with Hudson, Max manual gain can be very usefull particularly for embedded CBs when flying IMC or at night.
My technique (learned when a copilot by a flightdeck visitor who worked for the radar manufacturer) is to select say 100nm range, max man gain and tilt down until you get a solid semi circle of ground return, bring this ground return to around 50nm and then look on the 50nm scale - anything there will be a storm return. Then tilt up and see how high it goes, if its still there at 2 degrees down then if I can't see it out the window I avoid it by the sort of margins discussed above.
slamer - surely if it's considered nescessary deviating up to 40nm then if it all still looks bad it's worth going another 40 miles rather than "batonning down the hatches" I was held down coming across Italy with cbs everywhere a few years ago eventually we rerouted via Sardinia and France and ended up about 100nm west of our original track, the guy behind us who didn't reroute ended up with a hail dented nosecone. Why take chances?
My technique (learned when a copilot by a flightdeck visitor who worked for the radar manufacturer) is to select say 100nm range, max man gain and tilt down until you get a solid semi circle of ground return, bring this ground return to around 50nm and then look on the 50nm scale - anything there will be a storm return. Then tilt up and see how high it goes, if its still there at 2 degrees down then if I can't see it out the window I avoid it by the sort of margins discussed above.
slamer - surely if it's considered nescessary deviating up to 40nm then if it all still looks bad it's worth going another 40 miles rather than "batonning down the hatches" I was held down coming across Italy with cbs everywhere a few years ago eventually we rerouted via Sardinia and France and ended up about 100nm west of our original track, the guy behind us who didn't reroute ended up with a hail dented nosecone. Why take chances?
Last edited by Hobo; 29th Oct 2003 at 01:24.
Join Date: Oct 2002
Location: planit
Posts: 240
Likes: 0
Received 0 Likes
on
0 Posts
I agree with Sperm Bank and Kaptin M.
Is this a mutual stroking session or what? And why am I not invited?
The worst mothers of CB's I have struck anywhere in the world are in Oz.
Cute..but where in the world have you been besides Oz...
Evidently not South and central USA in spring....or perhaps Brazil, Argentina, Southern Africa, Southern Europe.
"The biggest and most powerful thunderstoms I have witnessed anywhere in the world are right here in Oz.", I too would concur with that.
Let you in on a little secret...the Kimberleys are in the tropics. More severe supercell and squall line Ts are more prevalent in SE Australia due to jet and cold fronts. Australia has not as severe Ts as some locations specified above due less air moisture and less differing airmass movements converging... I know, a Ts is scary stuff nevertheless, specially for you good weather flyboys. But please spare us all the drivel.
Join Date: Aug 2003
Location: South of zero
Posts: 330
Likes: 0
Received 0 Likes
on
0 Posts
What about NZ
You would all be surprised at some of the cells these little islands can produce. Huge amounts of ice and turbulence.
That aside it's always a safe bet to stay well clear of anything that looks harmful if you have no wx radar.
Shake, rattle and roll
splat
That aside it's always a safe bet to stay well clear of anything that looks harmful if you have no wx radar.
Shake, rattle and roll
splat
Guest
Posts: n/a
Sperm Bank .
A nice rule of thumb for lateral dist V Alt to aviod CB,s , however
in my opnion something of a luxury, Good theory, but not that practical,Can you honestly say you avoid all CB,s by as much as 40 nm ( I will assume you dont go much over 40000')
I know some operators have a min 10nm lat dist from ANY CB. I also know very few if any of their people actually do this (unless on a work to rule of course)
The operator I work for has no set policy/SOP on this, and to the best of my knowledge has never had a problem with upsets, either running into or passing close to CB,s while enroute. Naturally the terminal area can be a little more restricive on arrival/Departure and cause problems at times
Hobo,
Yeh figured someone would say that, My point is ,
One can nearly always find a safe path through a line of Wx with intelligent use of the radar system, (granted this may be a problem if your stuck low) It is very unusual to get a solid line of
red/magenta spanning 200nm +, when above 30000'
A few years ago we had an a/c req an en-route fuel diversion as a result of lat diversion in the order of hundreds of miles, From my experiance this is completley unnecessary if you know what your doing and plan ahead
But never say never eh!
anyway,nuff on this thread for me, over and out.
A nice rule of thumb for lateral dist V Alt to aviod CB,s , however
in my opnion something of a luxury, Good theory, but not that practical,Can you honestly say you avoid all CB,s by as much as 40 nm ( I will assume you dont go much over 40000')
I know some operators have a min 10nm lat dist from ANY CB. I also know very few if any of their people actually do this (unless on a work to rule of course)
The operator I work for has no set policy/SOP on this, and to the best of my knowledge has never had a problem with upsets, either running into or passing close to CB,s while enroute. Naturally the terminal area can be a little more restricive on arrival/Departure and cause problems at times
Hobo,
Yeh figured someone would say that, My point is ,
One can nearly always find a safe path through a line of Wx with intelligent use of the radar system, (granted this may be a problem if your stuck low) It is very unusual to get a solid line of
red/magenta spanning 200nm +, when above 30000'
A few years ago we had an a/c req an en-route fuel diversion as a result of lat diversion in the order of hundreds of miles, From my experiance this is completley unnecessary if you know what your doing and plan ahead
But never say never eh!
anyway,nuff on this thread for me, over and out.
Join Date: Jun 2001
Location: Ozmate
Posts: 376
Likes: 0
Received 0 Likes
on
0 Posts
Winstun,
You are an absolute fuc*wit mate!
Do you really think anyone is interested in your smartarse comments?
And yes I have flown in most of the places you mentioned you ACE!
Get dropped on your head as a child or something did you?
****** !!!!!!!!!
You are an absolute fuc*wit mate!
Do you really think anyone is interested in your smartarse comments?
And yes I have flown in most of the places you mentioned you ACE!
Get dropped on your head as a child or something did you?
****** !!!!!!!!!
Join Date: Feb 1999
Location: Perth Australia
Posts: 37
Likes: 0
Received 0 Likes
on
0 Posts
Just when I though there is hope for PPrune , with a great interesting discussion, that benifits all who read.
When along comes Winstun, I wish they would ban brain dead floggers like this. PPrune should have a separate forum for all these idiots, where they can all get in together and annoy each other.
To the rest of the writers in this post well done, a good subject that a lot of junior pilots know little about. Especially the use of Wx Radar.
When along comes Winstun, I wish they would ban brain dead floggers like this. PPrune should have a separate forum for all these idiots, where they can all get in together and annoy each other.
To the rest of the writers in this post well done, a good subject that a lot of junior pilots know little about. Especially the use of Wx Radar.