AF 747 hit severe weather between Rio and Paris
Join Date: Aug 2009
Location: Germany
Age: 67
Posts: 1,777
Likes: 0
Received 0 Likes
on
0 Posts
If on the other hand you have a crew blindly following a SID through a Cb , then you migh have a problem worth investigating, . But for the moment we do not know if that is thecase or not.
) .. maybe interesting ...
Pegase Driver
Thread Starter
Join Date: May 1997
Location: Europe
Age: 74
Posts: 3,692
Likes: 0
Received 0 Likes
on
0 Posts
I've heard 2nd hand that they had their radar on Auto and were avoiding what they saw on the radar. They said the hail area was not visible on the radar.
Join Date: Dec 2000
Location: on the golf course (Covid permitting)
Posts: 2,131
Likes: 0
Received 0 Likes
on
0 Posts
ATC Watcher
Not doubting what you say, and not wishing to teach granny how to suck eggs, but there are two different major controls on most radars of the B747-400 era.
The first is the 'gain' or the sensitivity of the radar to the returns received - for this to be in auto is quite usual and not to be criticised,
The second is the 'tilt' of the beam, which is under manual ie pilot control, and where on the B744's I flew, auto was not available. The tilt selected references where the beam is looking relative to the horizon and will vary in various flight phases, the beam itself being about 3-4 degrees wide. At TO, for example +10degrees might be appropriate, reducing to +2 to 5 degrees during the climb phase. In cruise flight, you obviously want to know what is at/around your level and so will point it lower than in the climb. At all stages thoough, you should vary the tilt up and down to build a better picture of the overall atmosphere. I believe that more recent developments provide automated 3D mapping for the crew.
So, whilst I agree that hail may well not provide a return in itself, then the hail is coming from some cloud structure that will, and that by using the tilt you should be able to 'see' formations worth avoiding.
Not doubting what you say, and not wishing to teach granny how to suck eggs, but there are two different major controls on most radars of the B747-400 era.
The first is the 'gain' or the sensitivity of the radar to the returns received - for this to be in auto is quite usual and not to be criticised,
The second is the 'tilt' of the beam, which is under manual ie pilot control, and where on the B744's I flew, auto was not available. The tilt selected references where the beam is looking relative to the horizon and will vary in various flight phases, the beam itself being about 3-4 degrees wide. At TO, for example +10degrees might be appropriate, reducing to +2 to 5 degrees during the climb phase. In cruise flight, you obviously want to know what is at/around your level and so will point it lower than in the climb. At all stages thoough, you should vary the tilt up and down to build a better picture of the overall atmosphere. I believe that more recent developments provide automated 3D mapping for the crew.
So, whilst I agree that hail may well not provide a return in itself, then the hail is coming from some cloud structure that will, and that by using the tilt you should be able to 'see' formations worth avoiding.
Join Date: Feb 2008
Location: somewhere
Posts: 93
Likes: 0
Received 0 Likes
on
0 Posts
ATC watcher
Good second hand !
They avoided weather along the SID , same weather avoidance on the way back after dumping .
Reading some Airbus documents on radar, 40 % of hail is outside the cumulonimbus , 60% inside. Dry hail has a "green reflectivity" looking as snow .
This can cure "jcjeant" " wish to read syndrome"
I've heard 2nd hand that they had their radar on Auto and were avoiding what they saw on the radar. They said the hail area was not visible on the radar.
They avoided weather along the SID , same weather avoidance on the way back after dumping .
Reading some Airbus documents on radar, 40 % of hail is outside the cumulonimbus , 60% inside. Dry hail has a "green reflectivity" looking as snow .
This can cure "jcjeant" " wish to read syndrome"
Aviator Extraordinaire
Join Date: May 2000
Location: Oklahoma City, Oklahoma USA
Age: 76
Posts: 2,394
Likes: 0
Received 0 Likes
on
0 Posts
filejw
Okay, a little confused here. What wind are you referring to? If it is the upper jet stream winds, that is a bit too much and unrealistic in my humble opinion. I've had upper winds in excess of 150 knots during the spring over the US (lower 48) which is uncommon, but certainly not unheard of.
As GF posted, the stardard is 20 miles downwind which I used for stardard garden variety style thunderstorms. But when a rapid moving cold front is moving across the country driven by jetstreams of over 100 plus knots with tops near FL500, I do give them more than 20 miles, more the better really.
So as you posted, giving them one mile for each knot of speed of the jet stream is great if you have the fuel and can talk ATC into such a large deviation.
CON ..1nm for every knot of wind works real well for downwind....
As GF posted, the stardard is 20 miles downwind which I used for stardard garden variety style thunderstorms. But when a rapid moving cold front is moving across the country driven by jetstreams of over 100 plus knots with tops near FL500, I do give them more than 20 miles, more the better really.
So as you posted, giving them one mile for each knot of speed of the jet stream is great if you have the fuel and can talk ATC into such a large deviation.
Join Date: Mar 2004
Location: Origae-6
Posts: 137
Likes: 0
Received 0 Likes
on
0 Posts
Wait! According to some posters on this forum this flight should have continued to its destination
Regards
Join Date: Apr 2005
Location: U.K.
Age: 68
Posts: 380
Likes: 0
Received 0 Likes
on
0 Posts
Wait! According to some posters on this forum this flight should have continued to its destination
I hope your not getting your threads confused;-) Big difference between flying through a hail shaft and flying a 4 engine airplane on 3 engines in cruise.
I think squawk 7777 might have been suggesting that flying a 3 engine heavy into another problem (like a Cb) thousands of miles later is a definite maybe and something which could be avoided by a return.
Especially when so many things can go wrong and those things are no respecter of being on 3 engines...
Murphy's Law?
Regards.
Join Date: Mar 2004
Location: Origae-6
Posts: 137
Likes: 0
Received 0 Likes
on
0 Posts
Dream Buster
Thanks for your reply. I did come off a little glib on my post in regards to 3 engine cruise but, I don't think I need to tell another professional pilot that one always considers his options during the cruise phase, weather being a big considerations. In my career I have had my share of long range 3 engine flights, most of them being engine out ferry's.
