View Full Version : B737 Classics.....Wx Radar Techniques

17th Sep 2005, 15:19
Hi All,
Im being trained for P1 on the 737 Classics. So i do spend a lot of time sitting at home and thinking how it'll be, trying to track storms brewing up at 35000 feet in the nightskys.

I have been handed down a few pointers on Wx Radars over the years by my mates, would love you guys to pitch in a few as well. And also tell me if you guys do follow the following stuff or not.....

1) Instead of Calibrated, select gain to -3 and stay off all yellow and reds (a bit tooooo conservative i feel)

2) above FL250, circumnavigate a CB cell by more than 25 NMs.

3) at a high cruise lvl...reduce the tilt angle of the radar, till you observe ground echo at about 80-90 NMs ahead...thats the tilt angle one would like to keep at that level...or maybe just above that angle.


17th Sep 2005, 18:48

I'm far from being a weather radar artist, since I fly weather radar equipped aircrafts only from a few months;)
For point 1, I think that it is not so conservative... yellow stuff is not really the most funny situation, while red can get you into serious troubles. Have you ever tried to get in between two nice red cells ? It happened to me a couple of times, and it's not so relaxing:}
When avoiding you also have to consider downwind and upwind conditions. There might be some huge Cb's that can still shake you in a good way in 25 nm range while downwind.
If I'm flying in a 80 nm Map Range, a select the tilt to have echoes on top of my screen, the classic green band that is caused by terrain returns. In 160 nm map range, I do more or less the same.
Anyway, waiting for some usefull replies to your question as well :cool:


18th Sep 2005, 01:39
First thing to do is obtain a copy of the Pilot Information Manual from the manufacturer of the radar. For example the Allied Signal RDR-4B Pilot's Manual with radar operating guidelines ACS-5082 August 2004. Or The Rockwell Collins WXR-700X Pilot's Guide.
You will be able to find a copy in your airline technical library -or should be able to. Rockwell Collins also publish a book called "Your Guide to Weather radar". The read the books from cover to cover, particularly some of the really good advice contained on high altitude radar interpretation using a combination of max gain and tilt.

Business and Commercial Aviation magazine (USA) has superb articles on radar use. Google it and you will be amazed what comes up. Radar interpretation is a fine art, but be prepared for every pilot you fly with having different opinions on it's use.

One thing is for sure. If dodgy weather is forecast it is wise to make sure the radar is operating before you take off, and not just the test pattern. At high altitude select the Gain control (if fitted) at the maximum gain position (not auto) and this enables the radar to pick up traces of moisture in the higher levels of thunderstorms which may top 50,000.

Auto gain will not pick up ice crystals present in anvil tops and you can blunder straight into turbulent tops 28,000 and above if you happen to be in 8/8 or at night. Max gain has a better chance of picking up the tiny echoes associated with a high CB top. Once you pick that up, then lower the tilt and search for the main part of the storm.

But never underestimate the importance of the smallest echo even 3 mm long on the screen at high altitude when in Max gain. It could be the invisible to radar top of a bloody great CB. Most reports of "unexpected" or "unreported clear air" turbulence encounters that throw people around is due to lack of close monitoring by the crew of the high level tops because of poor use of auto versus max gain, and poor use of the tilt control at high altitude.

Finally, even in clear weather use the radar to watch the isolated big clouds as they pass by and compare their visual appearance with how they show up on radar. Photograph them in your mind.
Differentiate between the "soft heavy rain" that occurs at low altitudes in tropical areas (lots of red on the radar but not dangerous) and "hard rain" from CB. If the screen is covered in red at low altitude (8000 ft down) in the tropics or over water, then reducing the gain to minimum will cut out most of the red echoes. The last red echo remaining on the screen is the one to avoid. This is personal opinion only, by the way.

18th Sep 2005, 15:22
It could be the invisible to radar top of a bloody great CB - to support Centaurus - ALWAYS keep the scanner moving down every now and then, because, as C says, there could be a 'bg' cb that is bubbling rapidly upwards towards your level, and with 'bg' cbs the upward air motion can continue for several thousand feet in clear air making a nasty bump.

I ALWAYS use max gain (737) to 'find' the wx, and assess its 'severity' in Auto. It enables you, for one thing, to make a smallish heading change at 50 miles instead of a panic '40 right' at 20 miles when it appears in 'Auto'.

I seem to recall someone called 'Archie Trammel'??? in the USA used to 'train' radar techniques. It is often (sadly) missed out on line training.

A few years ago I flew with a Captain one night who avoided the island of Jersey - 'wow - that's a big b**rd'. It seemed a shame to say anything.........:D

Edit to say it is Archie Trammel - just Google.

18th Sep 2005, 15:41
Gentlemen, Archie Tremmel IS THE MAN!!!

thanx BOAC, Centaur, and others. Your views were really enlightening indeed. I shall observe how Maxing the Gain would work out in hunting down cells and then increasing gain progressively to scan for the worst part of the cell.

and yes, google has a LOT of hits for the name Archie Tremmel, (thankfully all of them relate to the Wx Radar Guy himself!!)

anyone else would be still encouraged to give in their pointers collected by them over the years. Who knows, there might be PPrune's very OWN "Archie" emerging!!

thanx again.

18th Sep 2005, 15:46
YT- two minor typo corrections for others reading - 'TrAmmel' and 'lower TILT to scan for ' etc - gain is already at 'MAX'

.and for that Captain of mine - always go 10 nm UPWIND of Jersey:D :D

22nd Sep 2005, 13:08
All good stuff - may I throw these in?

In addition to scanning up and down, keep switching the range from close in (20 - 80nms) which is your tactical picture, to far off (80 - 320nms) which is your strategic picture. It's all too easy to get deeply involved with the close in one, only to discover when you have passed it that you are heading for a 'dead end' or a 'sucker's gap' which could have been avoided with strategic looks earlier on.

Try to go upwind of the big ones and be aware that, broadly speaking, CBs travel roughly with the 10,000' wind which may be significantly different to the wind at your cruise level if you are taking their drift into account on a long 'look'.


West Coast
23rd Sep 2005, 05:36
"I ALWAYS use max gain (737) to 'find' the wx"

People, repeat this a hundred times before you go to bed. I run the gain up and find the wx. I want to know if there is a glass of water out there. This technique being especially true in the desert SW of the US.

23rd Sep 2005, 08:55
I find it disturbing that a professional airline captain has to come onto the Pprune website to find out how to work the weather radar. He must have been a First officer for some years, as he is now getting his command. He appears to have been flying in the sub-continent. So, why has he not learnt the rudiments of the weather and the radar? This is to do with the safe operation of a commercial aircraft and basic airmanship...is he the right man for the job!!??
I hope the press miss this one.

23rd Sep 2005, 15:07
Openfly..the day you stop learning is the day you stop living. It is the very fact that he is a professional that he sought help and asked a question...
Openfly..I suppose you never ask questions..and you know all there is to know in your chosen field?

24th Sep 2005, 04:35
Yes i have been a First Officer (as if you havent ever been one) and yes i am being upgraded to P1 right now.

But i must inform that if PPrune does stick around for some years ahead, you might still find me joining and sparking off discussions in the coming years as well, even though i may be flying (who knows) a check pilot. Im sure a lot of the guys in these forums are Senior Flyers.

Dear Openfly, As a Young Professional Airline pilot, being an avid reader of Aviation Psychology, i would suggest to you books like The Naked Pilot (by David Beaty) and Emergency : Crisis on the Flight deck (By Stanley Stewart). You would be surprised to see how the "I am a captain...i know it all" attitude has caused so many mishaps in the past.

Atleast i wouldnt wanna end up with my name in these books as classic Macho Ego Examples........so i do my bit everyday to read up on something i may have read up already.....just keeping my learning curve pointing up......and pprune helps me in this endevour of mine.

happy landings.

p.s. thanks to haughtney1 for the rebuke.

25th Sep 2005, 13:29
Hey Openfly,

I expect Turk knows how to work the radar, and where all the switches are by now.

I suspect he is asking for guidance as to how to interpret the radar picture which I suppose is something developed by a lot of experience.

Anything can be done mechanically.........but is it for the best ?

25th Sep 2005, 13:58
;) Hey, I have got about 8 years on the classics and about 3 on the 777.

Using the weather radar, like nearly everything in aviation, is still a learning process. All the comments I read hear are common practices I have seen and used. Dont forget too that the wx out there is so so fluid.

I am running out with the kids now.....when I get a few mins I 'll jump in with a couple of techniques I use. Just had to get this one in though. Only the professionals ask questions. Good on you Young turk. Welcome to the left of the 737 classics.

25th Sep 2005, 16:25
Hey Brianigham, Thanx Mate for the encouraging words. ....waiting for your tips.....drop in anytime

26th Sep 2005, 19:05
hey young turk, i would be glad if you could take some time in the comming days and answer the PM i sent you!

thanks in advance