Weather avoidance
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I find this statement a bit disturbing in light of your original questions. I find it hard to believe someone is actually flying around this type of weather with the lack of understanding suggested by your questions.
As I had mentioned in one of my posts, I have gone through every possible literature I could ever lay my hands on about weather. I take the safer option of deviating all returns by 5-10nms, stay clear of all clouds tops by 5000ft.
The reason why I find Rockwell to be a bit on the sloppy side is, there have been times when I was still getting used to the transition from Honeywell 4000 to the Rockwell series, I noticed that it gave returns in auto mode with Cal gain at cruise FL, which disappeared when I used man tilt to scan 5000-6000 ft below me, leading me to falsely believe that the returns were due to CB well below me.
As I realised later they were the frozen tops of the clouds, not essentially CBs, which didn't show up due to lack of Temperature and altitude compensation in man mode. So it basically tells me to rely on the auto picture that it shows, rather than to do my scanning to find out the extent of the cloud and it's severity
In fact the manual of Rockwell states implicitly at some point to rely on all the automation that it provides. Hope I have made myself clear
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Long line, maybe 100+ miles, of big storms in Brazil. We're deviating upwind, which happens to be left/west as we're heading north. Impressive light show. Winds are about 80 kts from the NW so we're about 40 miles(?) upwind of the storms.
Here's where it gets crazy - the storms had enough outflow to change the winds to the east at about 30 kts. Neither of us had seen that big a change. In lighter winds had we seen a 10-20 kt wind shift direction near a storm? Sure. But to see a thunderstorm mass overcome 80 kts and generate an upwind outflow? That was very impressive.
Here's where it gets crazy - the storms had enough outflow to change the winds to the east at about 30 kts. Neither of us had seen that big a change. In lighter winds had we seen a 10-20 kt wind shift direction near a storm? Sure. But to see a thunderstorm mass overcome 80 kts and generate an upwind outflow? That was very impressive.
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5-10 miles is not sufficient downwind of thunderstorms. Our FOM says 20 mi minimum, and I have seen reports of hail damage beyond that.
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Regarding overfly, either directly or with a little lateral, beware of the OAT temp changes. If you have climbed above an inversion this may put a lid on the CB development. How strong is the inversion? Can you see it. As you approach the CB what do you think your vertical clearance is and is the inversion maintained?
If the CB looks like it might bust the inversion then watch out!! It's quite common to have an absolutely billiard table smooth top. It's also common to see a little mound trying to break free above the lid. Are the clouds pure thermal: what's the time of day? Growing or dissipating? Are you over mountains, perhaps orographic, or over flat lands/big cities perhaps thermic, or over sea. If they're frontal that's another matter about their development.
These are questions to be asked as you are approaching and spot them perhaps 200nm away and have 25mins to assess. It's astonishing how fast they can grow, but also how fast they can disappear when conditions change. Much will depend on your type a/c. If a turbo prop stuck in medium levels, watch out. If a jet flying with performance to spare perhaps you can use it, but if near your top limit you are like the TP at medium levels.
If the CB looks like it might bust the inversion then watch out!! It's quite common to have an absolutely billiard table smooth top. It's also common to see a little mound trying to break free above the lid. Are the clouds pure thermal: what's the time of day? Growing or dissipating? Are you over mountains, perhaps orographic, or over flat lands/big cities perhaps thermic, or over sea. If they're frontal that's another matter about their development.
These are questions to be asked as you are approaching and spot them perhaps 200nm away and have 25mins to assess. It's astonishing how fast they can grow, but also how fast they can disappear when conditions change. Much will depend on your type a/c. If a turbo prop stuck in medium levels, watch out. If a jet flying with performance to spare perhaps you can use it, but if near your top limit you are like the TP at medium levels.
If you really want the thrill of trying to weave your way between solid radar returns best you read through this accident report. You will never see a report like it in your lifetime you may hope!
http://kemhubri.dephub.go.id/knkt/nt...0GA%20Solo.pdf
It deals with a Garuda 737 that penetrated a 70,000 ft thunderstorm during the descent while attempting to navigate between build ups. Lack of maintenance on the radome meant returns were inaccurate. The result was a dual flame out in blinding rain and where the rain was ten times more heavy than certified during engine tests. That is why the engines flamed out. The APU failed to start due failed battery and thus total loss of all electrical power in IMC including standby instruments. The standby ADI was in the process of running down due to no electrical power and u/s battery when they glided out of the side of the CB.
By sheer astounding luck (and they sure needed it) they came out of the side of the CB at 8000 ft and spotted a river into which they ditched flapless with the loss of only one life.
And we still hear of airlines that consider practicing dead stick (Loss of All engines) landings in simulators as a waste of time. Tell that to the crew of the Boeing 767 "Gimli Glider) who ran out of fuel and dead sticked into a 4000 ft runway in Canada. As the captain stated later, if only he had been given just one dead stick practice landing in the simulator he would have approached the event with much more confidence that he could succeed.
http://kemhubri.dephub.go.id/knkt/nt...0GA%20Solo.pdf
It deals with a Garuda 737 that penetrated a 70,000 ft thunderstorm during the descent while attempting to navigate between build ups. Lack of maintenance on the radome meant returns were inaccurate. The result was a dual flame out in blinding rain and where the rain was ten times more heavy than certified during engine tests. That is why the engines flamed out. The APU failed to start due failed battery and thus total loss of all electrical power in IMC including standby instruments. The standby ADI was in the process of running down due to no electrical power and u/s battery when they glided out of the side of the CB.
By sheer astounding luck (and they sure needed it) they came out of the side of the CB at 8000 ft and spotted a river into which they ditched flapless with the loss of only one life.
And we still hear of airlines that consider practicing dead stick (Loss of All engines) landings in simulators as a waste of time. Tell that to the crew of the Boeing 767 "Gimli Glider) who ran out of fuel and dead sticked into a 4000 ft runway in Canada. As the captain stated later, if only he had been given just one dead stick practice landing in the simulator he would have approached the event with much more confidence that he could succeed.
Last edited by Centaurus; 16th Sep 2015 at 13:29.
Even our Ops manual says the same but in practical flying, with bare minimum reserve fuel, it kinda becomes a trade off between deviation and having reserve fuel left for any delay at Destination.
If you are that tight at destination how will you cope with a flap checklist on approach? I'm interested to know if there are companies where putting on a bit of gas for this would be questioned.
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I concur. Seldom do thunderstorms of that magnitude develop without forecast. Add enough fuel for diversion around the storms AND holding AND diversion to another airport if necessary.
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And if you need another reason to avoid flying over the tip of or through the anvil of even "garden variety" cells at high altitude, don't forget about terrestrial lightning-induced gamma ray bursts:
http://www.bbc.com/news/science-environment-30491840
You could have your nuts fried off and not even know it. I am POSITIVE that none of us here are compensated well enough to accept the Mother of All X-Rays to save 5 minutes of weather deviation fuel enroute.
While you are it it, if still on the fence about tankering that extra 1000 pounds of gas before crossing the "Itch" (ITCZ), enjoy this video by NASA explaining how said gamma-ray bursts blow antimatter into space (through your nuts, again):
https://m.youtube.com/watch?v=lXKt7UVjd-I
Can you say, "I'm calling in sick", boys and girls?
http://www.bbc.com/news/science-environment-30491840
You could have your nuts fried off and not even know it. I am POSITIVE that none of us here are compensated well enough to accept the Mother of All X-Rays to save 5 minutes of weather deviation fuel enroute.
While you are it it, if still on the fence about tankering that extra 1000 pounds of gas before crossing the "Itch" (ITCZ), enjoy this video by NASA explaining how said gamma-ray bursts blow antimatter into space (through your nuts, again):
https://m.youtube.com/watch?v=lXKt7UVjd-I
Can you say, "I'm calling in sick", boys and girls?
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RDR-4B
Last night, somewhere in Yangon FIR, our lovely RDR-4B showed a 20NM red cell at FL390, no high terrain anywhere in sight, full ground contact (tried ELEV, ON PATH, gain, still wouldn't go away) ... when we got closer (30 NM) the "cell" vanished without a trace.
Later on, between Chittagong and Kolkata, intense lightning ahead, our lovely radar was asleep, nothing on the display (tried max gain, elevation down up to FL290 still no returns) ... we started avoiding the beast by following traffic below and looking out for flashes ... when ~40NM from the beast, out of nowhere, a large (30-40NM) red/magenta circle appeared.
Can't trust this radar after that, no way to plan ahead ...
We were lucky to be on a populated track out of clouds at FL390, the radar was useless
Later on, between Chittagong and Kolkata, intense lightning ahead, our lovely radar was asleep, nothing on the display (tried max gain, elevation down up to FL290 still no returns) ... we started avoiding the beast by following traffic below and looking out for flashes ... when ~40NM from the beast, out of nowhere, a large (30-40NM) red/magenta circle appeared.
Can't trust this radar after that, no way to plan ahead ...
We were lucky to be on a populated track out of clouds at FL390, the radar was useless
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As mentioned, it is at low level on approach I get concerned and lacking in confidence. Example. Going into Gerona RW02 approaching from the east 4000'. ATC is giving CB's in the vicinity. There are hills directly west of the airfield within 10nm and mountains to the north. We spent a lot of time painting the area during descent and 25,000-15000' it seemed not too bad a prospect. We asked BCN for some radar Wx advice. Useless, and GRO didn't have any. It was daylight and it didn't seem too back and ugly. We proceeded to 4000' and were now looking at the hills. The deep red covered the airfield environment as well. We couldn't get rid of it. To venture in or divert? It still didn't look dark enough in the cloud to cause those tomatoes. In the end it was only heavy rain and a few bumps. We'd asked ATC about conditions over the airfield, cloud base, w/v, rain etc. and it seemed very doable. We were coming in over the sea and the wind was slightly NE pushing the clouds further inland.
With no outside information the radar gave us a No-Go picture. It is something I never managed to work out over 25 years of colour displays; how to achieve accurate low level returns with confidence.
With no outside information the radar gave us a No-Go picture. It is something I never managed to work out over 25 years of colour displays; how to achieve accurate low level returns with confidence.
Airbus guidance on the subject:https://www.google.co.uk/url?sa=t&rc...GenFDw&cad=rja
Thank you Tubby
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in case anyone stumbles across this thread and is looking for the airbus document, it seems airbus is not offering publicly anymore but you can maybe find it by googling like this:
https://www.google.de/search?q=FLT_OPS-ADV_WX-SEQ07
apart from that there is a new document about weather radar from airbus found here:
Library | Airbus, Commercial Aircraft
sorry for dredging up this thread but i thought it might help
edit: very nice training video https://www.youtube.com/watch?v=H_2NruqjQi4 (rockwell, some flaws from this thread discussed 45min onwards)
https://www.youtube.com/watch?v=WNVtJeccNSM (honeywell ... didn't watch yet)
https://www.google.de/search?q=FLT_OPS-ADV_WX-SEQ07
apart from that there is a new document about weather radar from airbus found here:
Library | Airbus, Commercial Aircraft
sorry for dredging up this thread but i thought it might help
edit: very nice training video https://www.youtube.com/watch?v=H_2NruqjQi4 (rockwell, some flaws from this thread discussed 45min onwards)
https://www.youtube.com/watch?v=WNVtJeccNSM (honeywell ... didn't watch yet)
Last edited by wiedehopf; 8th Aug 2017 at 20:31.
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How not to do it.
Bureau d'Enquêtes et d'Analyses pour la sécurité de l'aviation civile
Report
Serious incident on 22 July 2011 in cruise at FL350, north Atlantic Ocean to the Airbus A340-313 registered F-GLZU operated by Air France
Bureau d'Enquêtes et d'Analyses pour la sécurité de l'aviation civile
Report
Serious incident on 22 July 2011 in cruise at FL350, north Atlantic Ocean to the Airbus A340-313 registered F-GLZU operated by Air France
