737NG weather radar

[N1 Limit]

Hi guys
I was on the climb the other day and there was a cell just on my way and there was no returns on the radar,I pressed HDG select flew around just I was passing abeam the cloud it was very turbulent as a residual of the clouds,the radar was on AUTO-wax and turb tilt on +5.My question here is what's the optimum position for the radar in climb,cruise and descent with the tilt setting,and can anybody just explain me how Gain works better
Best Regards

[Centaurus]

a cell just on my way and there was no returns on the radar. More detail needed about height flying and height of CB tops. At high altitude in auto-gain on some radars there will be no return from clouds tops due no moisture. That is why at night or in IMC aircraft often get clobbered by severe turbulence due to CB top not visible on radar.

Again, on some radars it is best to set the gain control to max gain at high altitude and this usually gives a small echo which signifies a CB top. As some CB tops in the Pacific area can be over 63,000 ft known as super-cells, an inadvertent trip through that lot will shake you up and has been known to cause a dual flame-out. Happened to a Garuda 737 that made a dead stick flapless ditching. Max gain at high altitude cruise will usually give you a better chance of "seeing" ahead.

[Denti]

And a lot depends on what kind of weather radar is installed. Boeinf offers at least five different types of weather radar for the NG, it is basically a customer option. We use mainly a collins wx2100 installation which is actually much better in automatic mode than most pilots are in manual mode. Playing with gain can give additional info though, however more than one click of plus gain is usually too much.

[PCars]

One technique which may help is to select your flight path vector (FPV) on your PFD and note the degrees, (for example 3.0 degrees) and use that as a default tilt starting point for climb. 5 degrees is OK for takeoff but too high for an established climb. Leaving the tilt there will not give the complete picture. Use the enroute park position (tilt so as to leave a green band of ground return at the far edge of the ND) and vary the range from 40 to 80 during climb adjusting the enroute park picture to form a strategic plan -left or right or left then right then left etc. Adjust the stategic plan to a tactical maneuver when within 40 NM of the weather cells. Try to deviate upwind for turbulence avoidance.


Someone brought up the Collins 2100. For further study, when you have some extra time, Google WXR 2100 and select the smartcockpit 222 page PDF operator manual. I realize you don't have this type of radar on board, but just skim through it and look at the graphics and read about radar energy, reflectivity, beam width, and gain adjustment to get the gist of what the 2100 is doing. With your manual radar you are trying to form a mental picture of the weather threat, just like the 2100 is doing electronically. Good luck.

[EW73]

Not sure of the accuracy of this technique, but you may like to try it some day...

When approaching a CB buildup on your track...
Adjust the tilt/range to just see the very top of the buildup, then...
calculate:
(Selected range x 100) multiplied by (Tilt reading in degrees(-1.5 deg)) = height in feet the top of the CB is above your level.

Might be handy to know, if it can proven accurate in known conditions.

[N1 Limit]

@EW73 how do i use the tilt in order to see the top of the CB?thanks for the infos to everybody.

[Checkboard]

http://www.pprune.org/tech-log/48016-terminal-area-weather-radar-technique.html - Good PPRuNe TechLog thread :)

http://www.pprune.org/tech-log/10510-x-band-radar-tips.html - good PPRuNe TechLog thread :)

Weather radar, online information from Severewx.com (http://www.everythingweather.com/weather-radar/Weather_radar.shtml)

The Radar Theory Pages (http://www.radarpages.co.uk/theory/theoryindex.htm)

[Centaurus]

Adjust the tilt/range to just see the very top of the buildup

The problem with that technique is the radar may not "see" the actual top of the CB because there is very little moisture up there. That is why turning the Gain switch to MAX instead of AUTO may possibly give you a tiny return but not always. Radar interpretation is indeed an art of its own and you can obtain plenty of practice by observing CB visually then compare what you see outside with the radar picture.

[misd-agin]

+5 tilt is probably too high. That's a tilt angle for low altitude, that should decrease as you climb so that you're at approx. -1 in cruise(related to radar range selected)


You've entered the area of book knowledge vs. technique vs. experience.

For very low altitude work I actually decrease the sensitivity. High altitude I increase the sensitivity and use 'auto'(calibrated) for mid level weather.

Play with the radar tilt and gain settings to get the radar to display what your eye thinks it should see. Note those settings. After multiple experiences you'll have radar settings that you think work best.

At my carrier probably 80-90% of the guys increase the gain sensitivity above 'auto'(calibrated) in cruise and the most common tilt angle is probably -1 for cruise in the FL300-410 altitudes.