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AF 744 Returns To GIG After Hail Storm  
User currently offlineRodRB From Brazil, joined Feb 2010, 125 posts, RR: 0
Posted (1 year 1 month 1 week 2 days 17 hours ago) and read 22600 times:

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]

29 replies: All unread, showing first 25:
 
User currently offlineNoblert From United States of America, joined Sep 2010, 35 posts, RR: 0
Reply 1, posted (1 year 1 month 1 week 2 days 16 hours ago) and read 22286 times:

Wow. I would give a lot to not ever have to find out what that sounded like from inside.

User currently offlineAA737-823 From United States of America, joined Mar 2000, 5947 posts, RR: 11
Reply 2, posted (1 year 1 month 1 week 2 days 15 hours ago) and read 22222 times:

AF and Brazil and bad weather just don't seem to be a great mix.
Could the storm not be detected on weather radar?


User currently offlinemigair54 From Spain, joined Jun 2007, 1912 posts, RR: 1
Reply 3, posted (1 year 1 month 1 week 2 days 10 hours ago) and read 21104 times:

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.


User currently offlineSA7700 From South Africa, joined Dec 2003, 3431 posts, RR: 26
Reply 4, posted (1 year 1 month 1 week 2 days 10 hours ago) and read 21022 times:
AIRLINERS.NET CREW
HEAD MODERATOR

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)
User currently onlineB747forever From Sweden, joined May 2007, 17147 posts, RR: 10
Reply 5, posted (1 year 1 month 1 week 2 days 9 hours ago) and read 20813 times:

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
User currently offlineairproxx From France, joined Jun 2008, 641 posts, RR: 1
Reply 6, posted (1 year 1 month 1 week 2 days 9 hours ago) and read 20137 times:

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
User currently offlineDiamondFlyer From United States of America, joined Oct 2008, 1632 posts, RR: 3
Reply 7, posted (1 year 1 month 1 week 2 days 9 hours ago) and read 19690 times:

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


User currently offlineairmagnac From Germany, joined Apr 2012, 321 posts, RR: 52
Reply 8, posted (1 year 1 month 1 week 2 days 8 hours ago) and read 18573 times:

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  



One "oh shit" can erase a thousand "attaboys".
User currently offlinegoboeing From United States of America, joined Jun 2000, 2725 posts, RR: 15
Reply 9, posted (1 year 1 month 1 week 2 days 8 hours ago) and read 18463 times:

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.

User currently offlinemigair54 From Spain, joined Jun 2007, 1912 posts, RR: 1
Reply 10, posted (1 year 1 month 1 week 2 days 7 hours ago) and read 17360 times:

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,


User currently offlineSpacepope From Vatican City, joined Dec 1999, 2987 posts, RR: 1
Reply 11, posted (1 year 1 month 1 week 2 days 7 hours ago) and read 16601 times:

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
User currently offlineHNLsurfer From United States of America, joined Feb 2009, 48 posts, RR: 0
Reply 12, posted (1 year 1 month 1 week 2 days 7 hours ago) and read 16605 times:

It could also take out the pitot tubes and other instruments mounted on the exterior which obviously could be catastrophic

User currently offlineL0VE2FLY From United States of America, joined Dec 2012, 1636 posts, RR: 0
Reply 13, posted (1 year 1 month 1 week 2 days 5 hours ago) and read 14736 times:

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.


User currently offlineglbltrvlr From United States of America, joined Oct 2007, 770 posts, RR: 0
Reply 14, posted (1 year 1 month 1 week 2 days 4 hours ago) and read 14230 times:

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


User currently offlinejetblueguy22 From United States of America, joined Nov 2007, 2838 posts, RR: 4
Reply 15, posted (1 year 1 month 1 week 2 days 4 hours ago) and read 13867 times:
AIRLINERS.NET CREW
HEAD MODERATOR

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



All of the opinions stated above are mine and do not represent Airliners.net or my employer unless otherwise stated.
User currently offlinePihero From France, joined Jan 2005, 4673 posts, RR: 77
Reply 16, posted (1 year 1 month 1 week 2 days 3 hours ago) and read 13111 times:
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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
User currently offlineYWG From Canada, joined Feb 2001, 1147 posts, RR: 2
Reply 17, posted (1 year 1 month 1 week 2 days 3 hours ago) and read 12455 times:

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.
User currently offlinePGNCS From United States of America, joined Apr 2007, 2858 posts, RR: 48
Reply 18, posted (1 year 1 month 1 week 2 days 3 hours ago) and read 12153 times:

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.


User currently offlineDC9super80 From Denmark, joined May 2013, 14 posts, RR: 0
Reply 19, posted (1 year 1 month 1 week 2 days 2 hours ago) and read 12087 times:

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?

User currently offlineViscount724 From Switzerland, joined Oct 2006, 26005 posts, RR: 22
Reply 20, posted (1 year 1 month 1 week 2 days 2 hours ago) and read 11662 times:

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



User currently offlineAR385 From Mexico, joined Nov 2003, 6603 posts, RR: 35
Reply 21, posted (1 year 1 month 1 week 2 days 2 hours ago) and read 11320 times:
Support Airliners.net - become a First Class Member!

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.


User currently offlineArmitageShanks From UK - England, joined Dec 2003, 3645 posts, RR: 15
Reply 22, posted (1 year 1 month 1 week 2 days 1 hour ago) and read 11167 times:

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.

User currently offlineScottishDavie From UK - Scotland, joined Feb 2011, 188 posts, RR: 0
Reply 23, posted (1 year 1 month 1 week 2 days 1 hour ago) and read 11119 times:

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]

User currently offlinemd80fanatic From United States of America, joined Apr 2004, 2661 posts, RR: 9
Reply 24, posted (1 year 1 month 1 week 2 days 1 hour ago) and read 10772 times:

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.


25 dirtyfrankd : 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?
26 cornutt : Southern Airways Flight 242.
27 flyenthu : Why did the cockpit crew not allow for a wide margin from the edge of the storm? Was it a mistake of some sort?
28 goldorak : 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
29 francoflier : All they did was to fit a continuous ignition system which could be switched on inflight for these exact occurrences. All modern airliner engines hav
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