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Dangers of Flying over a Tropical Storm

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Dangers of Flying over a Tropical Storm

Old 24th Sep 2019, 22:55
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Dangers of Flying over a Tropical Storm

Does anyone have any documentation of the dangers of flying Commercial airplanes over a Tropical Storm?
I知 not speaking of the obvious dangers of thunderstorms as some storms have big enough gaps which can be navigated.
I知 speaking of the Low pressure , shifting winds etc.

Last edited by B888; 24th Sep 2019 at 23:11.
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Old 25th Sep 2019, 00:34
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At what height are you considering?

Tropical Storm systems are primarily a low level phenomena other than the convective weather that exists. At high level, avoidance of the convective weather gives a reasonable transit. Routinely flightpaths for jet transports will pass over a storm system. Weather avoidance increases track miles flown so affects fuel and time for the transit. Turbulence is mainly associated with the convective weather. Next storm of note, go and look at windy.com, and look at the difference in vectors for sea level, and higher altitudes. Right now there is a storm developing just west of the cape verde islands that shows the change with altitude clearly.
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Old 25th Sep 2019, 00:46
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Airlines usually route around Tropical Storms. The concern is a pressurisation failure and rapid descent
to 10,000 feet or lower. Not somewhere I would like to be.
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Old 25th Sep 2019, 01:51
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FL380 To FL400
The pressurization failure scenario is good to note.
Ice crystal icing does occur near these weather phenomena
Inversions also occur. There was an airplane from my mob which flew close to a storm and the temperature changed from -50 degrees to -37 degrees at FL380.
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Old 25th Sep 2019, 12:52
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Company I work for will plan me straight through a tropical depression because their books say they can. Unless the storm system is declared as a Cyclone, Typhoon or whatever then they'll plan it. Can get interesting, particularly if you're unlucky enough to be enroute and the weather folk sitting comfortably on the ground declare the system is now a Cyclone. Bit late then I'd say. I've seen ISA deviations from +15 (typical in the area I fly) shoot up to +30 when flying over tropical circular Lows and these weren't fully developed storm systems. A few hours later they were. Documentation I can't provide but watch out for the temperature rise if trying to climb above these weather systems. It's worth having a read of your company ground planning manuals about their reasoning on planning of the route. The devil could be in the detail.
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Old 25th Sep 2019, 14:47
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Originally Posted by AnthonyMachin View Post
Airlines usually route around Tropical Storms. The concern is a pressurisation failure and rapid descent
to 10,000 feet or lower. Not somewhere I would like to be.
That would rule out flying over the Himalayas as well?
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Old 25th Sep 2019, 15:05
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Airlines routing over Tibet have to carry extra oxygen to account for the lowest safe altitude.

Flying into a weather system will see your ISA deviation go up, I’ve seen in excess of ISA +20, which means your recommended MAX ALT goes down so make sure you have a good margin before entering. The associated turbulence would warrant a decent spread between the upper and lower limits displayed on the ASI as well.

Avoid weather at your upper altitude limit with a narrow coffin corner.
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Old 25th Sep 2019, 20:21
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Basically dont

Obviously the answers are from those who haven t transited a virulent ITCZ.
The tops around the equator are above service ceiling.
Done my bit of trying to out climb a cell or going twixt two with max continuous and wouldn't recommend it.
AF447 is an example
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Old 25th Sep 2019, 21:54
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Yes. When it says frequent CB tops FL550+, that痴 a clue to avoid.

A small angular deviation a long way away to be clear of the whole lot is more efficient than lots of manoeuvring around storms at close range, anyway.
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Old 25th Sep 2019, 22:52
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Originally Posted by Rabbit 1 View Post
Company I work for will plan me straight through a tropical depression because their books say they can. Unless the storm system is declared as a Cyclone, Typhoon or whatever then they'll plan it. Can get interesting, particularly if you're unlucky enough to be enroute and the weather folk sitting comfortably on the ground declare the system is now a Cyclone. Bit late then I'd say. I've seen ISA deviations from +15 (typical in the area I fly) shoot up to +30 when flying over tropical circular Lows and these weren't fully developed storm systems. A few hours later they were. Documentation I can't provide but watch out for the temperature rise if trying to climb above these weather systems. It's worth having a read of your company ground planning manuals about their reasoning on planning of the route. The devil could be in the detail.
That is what Capts decisions are for... Been there done that added an additional hour or so... Storms/ weather equals take more fuel! Now if you are heavy and at max then if you have no choice but to take FP fuel (can稚 see offloading an option), then make sure plenty of 双uts along the way.

Weather, respect it or it bites.

Yes have hmmmm learnt the hard way at times!
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Old 26th Sep 2019, 00:56
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Problem with trying to out climb weather, is you get too high for the "G" protection of the A/C.1.3VS. minimum,. or in the FL310/330 max depending on weight and temp of course, you get good "G" protection. As long as you penetrate below max turbulence speed, the A/C should hold together. A/C are build strong!. Sure you're in for a rough ride but stall out and you're in trouble, as was mentioned above..<br /><br />Oh the Commander should be in His/Her seat, not in the bunk, segregated or otherwise, negotiating thunderstorms and or the ITCZ.

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Old 26th Sep 2019, 04:42
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The recommendation is if you are overflying a CB to be at least 5000' above it , difficult with tops around FL400.

Weather showing on your radar 80 miles ahead which looks acceptable can be very different when you arrive there 10-15 minutes later. During that time cells can easily build up and returns get stronger as you get closer.
​​​​
A towering CU doesn't show up very well due to its low water content but the turbulence can be quite severe so use mark 1 eyeball in addition to the radar
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Old 26th Sep 2019, 06:16
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Flying over tropical rotating storms doesn't present many issues - I've done it a few times. I would prefer not to, but sometimes you have no choice. The OP may be asking about a fairly standard interview question about the threats of doing so, for which the standard answer is that the OAT will rise, so if you are close to your maximum altitude, you may have to descend.
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Old 26th Sep 2019, 11:55
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As Dan W says, flying over a rotating storm isn't a big deal.
If you're talking about flying over a bunch of Cbs, forget it. In the tropics they usually top out way over 50K feet. but the big gotcha is that when building they rise at a phenomenal rate. No outclimbing them and the tops are usually extremely turbulent. Then there are the temperature variations to consider. About 40-50 miles deviation sounds good, at least over the Pacific, I have no idea about the Atlantic.
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Old 26th Sep 2019, 17:57
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Building

Once tried to outclimb a building CB over northern France...ex luftwaffe starfighter captain looked at me..max continuous power and wind back the speed...s##t myself whilst the skipper had this impish grin of **** alan..never tried it again.
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Old 27th Sep 2019, 00:07
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Originally Posted by Dan Winterland View Post
Flying over tropical rotating storms doesn't present many issues - I've done it a few times. I would prefer not to, but sometimes you have no choice. The OP may be asking about a fairly standard interview question about the threats of doing so, for which the standard answer is that the OAT will rise, so if you are close to your maximum altitude, you may have to descend.
Thanks for all the replies of which I do agree to most, having flown medium/heavies for 20+ years.
But what I really wanted was hard evidence/ documentation of the dangers of flying over/close to Tropical Storms/Cyclones.
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Old 27th Sep 2019, 03:19
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I will throw it out there that it depends on the intensity and that every weather pattern is different.

I have flown over a weak tropical depression that became a typhoon a few moons ago. You could clearly see the weather pattern on the radar. Was it rough? No. Was it smart? Hmmmm on reflection probably not as I wouldn’t do it again. It is amazing what thought processes go through your mind at 4am on a 2 crew red eye.....

Thats just it in my eyes, weather can and will do anything, predictions aside, it’s nature!

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Old 27th Sep 2019, 15:49
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What should be interesting next time you fly over a tropical storm/depression/hurricane is a comparison of displayed pressure altitude and GPS altitude. I suspect that you will find as you approach the tropical storm and the air pressure reduces the aircraft will start to descend in 'real GPS altitude' which will show continually lower vertical distance above the geoid, while the pressure altitude will remain the same.

It raises the question of whether it is time to move to GPS altitudes as it would save all the real height descending and climbing but also significantly reduce altimeter pressure setting errors which are surprisingly common if ASRS is to be believed.
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Old 27th Sep 2019, 16:14
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A tropical storm has winds of 34-63 kts. They're typically 100-300 miles (160-480 km) diameter. We routinely flow over, and sometimes into, tropical storms. If you're in an area with 34-50 kts winds, if the convective weather isn't a major concern, operations will continue.
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