RodRB
Topic Author
Posts: 75
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AF 744 Returns To GIG After Hail Storm

Wed Nov 13, 2013 9:26 am

AF flight 443 returned to GIG shortly after takeoff yesterday, november 12th. It was hit by a hail storm and suffered some damages:



Photos by Alessandro Santos (GIG Group on Facebook)

How dangerous can be a hail storm?

Thanks

[Edited 2013-11-13 01:28:31]
 
NobleRT
Posts: 34
Joined: Wed Sep 22, 2010 9:23 pm

RE: AF 744 Returns To GIG After Hail Storm

Wed Nov 13, 2013 10:25 am

Wow. I would give a lot to not ever have to find out what that sounded like from inside.
 
AA737-823
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RE: AF 744 Returns To GIG After Hail Storm

Wed Nov 13, 2013 10:34 am

AF and Brazil and bad weather just don't seem to be a great mix.
Could the storm not be detected on weather radar?
 
migair54
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RE: AF 744 Returns To GIG After Hail Storm

Wed Nov 13, 2013 4:08 pm

Quoting AA737-823 (Reply 2):
Could the storm not be detected on weather radar?

No, but they might think it was not so bad, Basically weather radar detects water in the sky, so a hail storm will always be visible with the radar, for example CAT is not visible because there´s no water in it.

Quoting RodRB (Thread starter):
How dangerous can be a hail storm?

Very dangerous, not only because of damage on the plane (windows, radome, lights) but also because severe icing over control surfaces and excessive water and hail can even flame out engines. There´s a pic of an A319 of Easyjet in the database I think in GVA, it´s amazing the damage on the nose.
 
SA7700
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RE: AF 744 Returns To GIG After Hail Storm

Wed Nov 13, 2013 4:17 pm

This looks really bad... I'm glad I was not on that plane.  
Quoting migair54 (Reply 3):
There´s a pic of an A319 of Easyjet in the database I think in GVA, it´s amazing the damage on the nose.

Here are some more examples:


View Large View Medium
Click here for bigger photo!

Photo © Dave Broome
View Large View Medium
Click here for bigger photo!

Photo © Kenji Satoh




Regards,

SA7700
When you are doing stuff that nobody has done before, there is no manual – Kevin McCloud (Grand Designs)
 
B747forever
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RE: AF 744 Returns To GIG After Hail Storm

Wed Nov 13, 2013 4:37 pm

Wow, that looks really bad.

Quoting Noblert (Reply 1):
Wow. I would give a lot to not ever have to find out what that sounded like from inside.

Cant imagine how it must have sounded like for those sitting in the first row.
Work Hard, Fly Right
 
airproxx
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RE: AF 744 Returns To GIG After Hail Storm

Wed Nov 13, 2013 5:08 pm

Quoting migair54 (Reply 3):

No, but they might think it was not so bad, Basically weather radar detects water in the sky, so a hail storm will always be visible with the radar, for example CAT is not visible because there´s no water in it.

Hail IS NOT detected by weather radar. Only liquid water.
If you can meet with triumph and disaster, and treat those two impostors just the same
 
DiamondFlyer
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RE: AF 744 Returns To GIG After Hail Storm

Wed Nov 13, 2013 5:26 pm

Quoting airproxx (Reply 6):
Hail IS NOT detected by weather radar. Only liquid water.

Seriously, are you implying that then snow doesn't show up on radar either?

-DiamondFlyer
From my cold, dead hands
 
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airmagnac
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RE: AF 744 Returns To GIG After Hail Storm

Wed Nov 13, 2013 6:09 pm

This could be a useful read :
http://www.airbus.com/fileadmin/medi...afetyLib_-FLT_OPS-ADV_WX-SEQ07.pdf

In short : it's somewhat complicated  
My goal as an engineer is to fill my soul with coffee and become immortal
 
goboeing
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RE: AF 744 Returns To GIG After Hail Storm

Wed Nov 13, 2013 6:13 pm

Going forward in the argument/debate that ensues in this thread, you should all distinguish whether you are talking about radar from a ground station or the radar that is available in the cockpit from the dish behind the radome.
 
migair54
Posts: 2179
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RE: AF 744 Returns To GIG After Hail Storm

Wed Nov 13, 2013 7:02 pm

Quoting airproxx (Reply 6):
Hail IS NOT detected by weather radar. Only liquid water.

The hail is not floating in the sky, it´s inside the CB´s and believe me, they are clearly visible in the weather radar because they are usually full of water (the CB not the hail itself), not all have hail, that´s the difference, and the Hail precipitation comes with rain.

I know that there´s no a specific colour in the plane radar for the hail, I should have said this maybe. Anyway I´m sure that every pilot in this foro agree that the best we can do is avoid the CB´s, even with a B747 or a Caravan, the power of that things is huge and they are really dangerous. I have been in a few hail situations and just the noise in the cockpit is scary, the turbulence, the lightings, the drafts, it´s a really serious issue, Actually is a reportable weather occurrence like wind-shear.

Quoting goboeing (Reply 11):
Going forward in the argument/debate that ensues in this thread, you should all distinguish whether you are talking about radar from a ground station or the radar that is available in the cockpit from the dish behind the radome.

Exactly,
 
Spacepope
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RE: AF 744 Returns To GIG After Hail Storm

Wed Nov 13, 2013 7:30 pm

Quoting SA7700 (Reply 4):
Here are some more examples:

IIRC this Air Transat L1011 was W/O after this hail encounter.


View Large View Medium
Click here for bigger photo!

Photo © Ariel Shocrón

The last of the famous international playboys
 
HNLsurfer
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RE: AF 744 Returns To GIG After Hail Storm

Wed Nov 13, 2013 7:31 pm

It could also take out the pitot tubes and other instruments mounted on the exterior which obviously could be catastrophic
 
L0VE2FLY
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RE: AF 744 Returns To GIG After Hail Storm

Wed Nov 13, 2013 9:07 pm

Quoting Spacepope (Reply 11):
IIRC this Air Transat L1011 was W/O after this hail encounter.

TS started to retire all their L-1011s around that time anyway, I'm sure they would have repaired her if she was a young bird.
 
glbltrvlr
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RE: AF 744 Returns To GIG After Hail Storm

Wed Nov 13, 2013 9:36 pm

Quoting airproxx (Reply 6):

Hail IS NOT detected by weather radar.

But other indications of potential hail can be detected with the right radar:

http://www.newfromhoneywell.com/system_features.php
 
jetblueguy22
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RE: AF 744 Returns To GIG After Hail Storm

Wed Nov 13, 2013 9:55 pm

Quoting airproxx (Reply 6):
Hail IS NOT detected by weather radar. Only liquid water.

You will absolutely get a return for hail on weather radar. But what you may not be able to distinguish is whether or not it is hail or liquid water. Dry hail's reflectivity is low, so it may be hard tough to distinguish from a rain shower, but wet hail will reflect a lot of energy back. But again distinguishing it is more the issue.

Quoting HNLsurfer (Reply 12):
It could also take out the pitot tubes and other instruments mounted on the exterior which obviously could be catastrophic

Luckily there is some redundancy, but that would be a scary situation losing all your pitot tubes.

I can't imagine being onboard that airplane. It had to be a very scary event. There isn't much that really gets my blood pumping in an airplane, but that would get me going for sure. AF doesn't seem to have much luck on flights from Brazil, but the pilots did a good job of getting the aircraft and ultimately the passengers back safe. Rattled though I'm sure.
Pat
Look at sweatpants guy. This is a 90 million dollar aircraft, not a Tallahassee strip club
 
Pihero
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RE: AF 744 Returns To GIG After Hail Storm

Wed Nov 13, 2013 10:34 pm

So, if I understand you well : you see it but you don't see it ; Right ?
What people on this thread are missing is that in many ways, radar use and interpretation is more a formof art and experience than technology.
It takes years of dedication to begin understanding what one really sees and interprets.

NO ! Your radar doesn't detect either dry hail or dry snow : It's onlywhen they exist with mliquid water than the returnsare visible... as water, i.e rain drops. Scanning a Cb, if one sees a shadow behind the strongest return, you could with a great deal of certainty that hail is present... but as you would avoid that zone anyway, that knowledge is moot.

Hail encounter most of the time occurs below the anvil of a well developped Cb and by definition, it is dry, therefore invisible... That's the main reason we avoid thyose clouds with a wide margin.

Other instances are Cbs embedded in a Stratocumulus cloud, with a lot of rain : detecting it requires a very vigilant and attentive pilot switched on operating gain and tilt during - here - the climb... In these conditions, the slightest lag in operating these controls might get you in all sorts of trouble.

Quoting jetblueguy22 (Reply 15):
that would be a scary situation losing all your pitot tubes.

That's quite unlikely. Pitot tubes are very sturdy... But the pîtot sensors can very well be disturbed by the radome deformation or destruction... another unreliable airspeed situation.
Contrail designer
 
YWG
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RE: AF 744 Returns To GIG After Hail Storm

Wed Nov 13, 2013 11:13 pm

Hail also has a habit of damaging compressor blades which can lead to surging and engine flameouts.
Contact Winnipeg center now on 134.4, good day.
 
PGNCS
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RE: AF 744 Returns To GIG After Hail Storm

Wed Nov 13, 2013 11:32 pm

Quoting AA737-823 (Reply 2):
Could the storm not be detected on weather radar?

The storm can almost certainly be detected, however hail can be ejected far from the storm and hail shafts cannot be detected by onboard radar.

Quoting airproxx (Reply 6):
Hail IS NOT detected by weather radar.

Correct.

Quoting DiamondFlyer (Reply 7):
Quoting airproxx (Reply 6):Hail IS NOT detected by weather radar. Only liquid water.
Seriously, are you implying that then snow doesn't show up on radar either?

I don't know how much experience you have in operating radars on commercial airliners (I've been at it since 1988) but frozen precipitation is generally not detectable with onboard equipment, though there may be liquid phase water coexisting in the same clouds. Depending on the exact makeup of the weather you may see detectable moisture or you may see nothing depending on the exact phase of the water in the clouds.

Quoting migair54 (Reply 10):

The hail is not floating in the sky, it´s inside the CB´s and believe me, they are clearly visible in the weather radar because they are usually full of water (the CB not the hail itself), not all have hail, that´s the difference, and the Hail precipitation comes with rain.

Again the storms are detectable, but the hail is not always inside the storms as you incorrectly believe.

Quoting jetblueguy22 (Reply 15):
You will absolutely get a return for hail on weather radar.

No you won't.

Quoting Pihero (Reply 16):
What people on this thread are missing is that in many ways, radar use and interpretation is more a formof art and experience than technology.

That is absolutely correct. Radar use is one of the most difficult skills to learn and use effectively.

Quoting Pihero (Reply 16):
It takes years of dedication to begin understanding what one really sees and interprets.

Absolutely.

Quoting Pihero (Reply 16):
NO ! Your radar doesn't detect either dry hail or dry snow

Correct.

Quoting Pihero (Reply 16):
Hail encounter most of the time occurs below the anvil of a well developped Cb

And as such is outside of the storm detectable on radar. This is why we give these cells such a wide berth, especially downwind of them.

Quoting Pihero (Reply 16):
Other instances are Cbs embedded in a Stratocumulus cloud, with a lot of rain : detecting it requires a very vigilant and attentive pilot switched on operating gain and tilt during

Yes indeed. It is a skill that takes many years to learn.
 
dc9super80
Posts: 36
Joined: Sun May 12, 2013 1:26 pm

RE: AF 744 Returns To GIG After Hail Storm

Wed Nov 13, 2013 11:37 pm

I guess that a lot of the time there is big convective clouds in this part of the world, so these things are bound to happen?
 
Viscount724
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RE: AF 744 Returns To GIG After Hail Storm

Thu Nov 14, 2013 12:08 am

Quoting Spacepope (Reply 11):
Quoting SA7700 (Reply 4):
Here are some more examples:

IIRC this Air Transat L1011 was W/O after this hail encounter.

Other photos of the Air Transat L-1011 hail damage here.
http://www.avherald.com/h?article=42fca893&opt=0

And the EasyJet Switzerland 733 that encountered hail after takeoff from GVA for LTN in 2003.

http://avherald.com/img/easyjet_hail.png

 
AR385
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RE: AF 744 Returns To GIG After Hail Storm

Thu Nov 14, 2013 12:30 am

Quoting migair54 (Reply 3):
but also because severe icing over control surfaces and excessive water and hail can even flame out engines.

After the engine less landing of that TACA 737-300 in New Orleans the engines were redesigned and rain and hail during normal encounters do not cause engine flameout.
 
ArmitageShanks
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RE: AF 744 Returns To GIG After Hail Storm

Thu Nov 14, 2013 12:43 am

A bit off topic about weather radar in aircraft but here goes. How strong is the beam coming out of the nose? 320 mile returns sound like it has to be pretty harmful to anyone standing in front of it when its on.
 
ScottishDavie
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RE: AF 744 Returns To GIG After Hail Storm

Thu Nov 14, 2013 12:47 am

The discussion about what does or doesn't show up on radar becomes a little bit academic if the crew switch off the weather radar as happened in this incident:
http://www.pprune.org/rumours-news/1...storm-damage-radar-turned-off.html

Most of the links in the pprune piece no longer work but it appears that the crew followed BD's then current SOP which I assume was subsequently changed!

[Edited 2013-11-13 16:48:54]
 
md80fanatic
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RE: AF 744 Returns To GIG After Hail Storm

Thu Nov 14, 2013 1:17 am

Radar detects anything that will reflect enough of it's radiation back to the emitter, where it's interpreted and displayed. Chunks of ice reflect some of the beam from the surface patches perpendicular to the oncoming radiation. Sadly, the returned signal is not bold enough to register well, if at all. A water droplet is like a prism, they reflect much and "brightly".

There is still one tried and true method for detecting hail and that is meteorological knowledge and experience. Hail doesn't form out of nowhere, the mechanics of formation have been known for some time. Each hail producing cell features incredible fast-moving vertical columns of air, fast enough to hold aloft a baseball, for example. Detecting cells like these may be beyond commercial radars in today's cockpits, but are child's play for fixed installations on the ground.
 
dirtyfrankd
Posts: 182
Joined: Tue Apr 26, 2011 3:10 am

RE: AF 744 Returns To GIG After Hail Storm

Thu Nov 14, 2013 1:50 am

On a side note, when did AF start using 744s on this route. I thought they were using a combination of A-330/A-340 for this route?
 
cornutt
Posts: 333
Joined: Sun Jan 20, 2013 6:57 am

RE: AF 744 Returns To GIG After Hail Storm

Thu Nov 14, 2013 2:49 am

Quoting YWG (Reply 17):
Hail also has a habit of damaging compressor blades which can lead to surging and engine flameouts.

Southern Airways Flight 242.
 
flyenthu
Posts: 547
Joined: Fri Dec 21, 2012 2:37 pm

RE: AF 744 Returns To GIG After Hail Storm

Thu Nov 14, 2013 5:18 am

Why did the cockpit crew not allow for a wide margin from the edge of the storm? Was it a mistake of some sort?
 
goldorak
Posts: 1369
Joined: Sat Sep 09, 2006 5:29 am

RE: AF 744 Returns To GIG After Hail Storm

Thu Nov 14, 2013 5:59 am

Quoting dirtyfrankd (Reply 25):
On a side note, when did AF start using 744s on this route.

I don't know when they started but it was many years ago. One flight is operated by B744, the other one by A332. AF announced recently that the B777 will soon replace the B744 on this route
 
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Francoflier
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RE: AF 744 Returns To GIG After Hail Storm

Thu Nov 14, 2013 7:44 am

Quoting AR385 (Reply 21):
After the engine less landing of that TACA 737-300 in New Orleans the engines were redesigned and rain and hail during normal encounters do not cause engine flameout.

All they did was to fit a continuous ignition system which could be switched on inflight for these exact occurrences.
All modern airliner engines have such a system now, either manually or automatically switchable.

It could have prevented the TACA mishap, but it does not guarantee that it will recover the engine from a flameout in any weather phenomena. Massive rain/hail storms associated with shearing winds can still cool the engine core and disrupt its airflow beyond the igniters' capacity to keep the flame alive.

No matter the aircraft, stay well clear of these clouds...
I'll do my own airline. With Blackjack. And hookers. In fact, forget the airline.

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