eaglefly

Well, if this "encounter" wasn't enough to spill any coffee from a passengers cup, then I have to wonder why they diverted ?

Overreaaction and/or hysteria on the part of an inexperienced flightcrew ?

fosters

I agree with your analysis that he is using it wrong but even your way of using it is incorrect. Well not incorrect, it will keep you alive but the return won't be accurate, it will overpaint weather. You will go around things you don't need to go around.

The goal of weather RADAR is to aim the beam somewhere between FL180 and 250 depending on who you listen to. David Gwinn says FL180. Archie Trammel says FL 250. Anyways. I use FL250 as a worst case "if I have to penetrate" level.

OK, how to aim it at that level?

Every 10 miles 1* of tilt changes the beam center by 1000' of your altitude.

What does that mean? If you want to aim it at FL250:

Q) You are at FL 250. Where should the tilt be?
A) 0* no matter what the range.

Q) If weather is 30 miles away and you are at 15,000, where should the tilt be?
A) Right around 3.2*. That will give you an accurate return on that weather.

Q) If you are on the ground departing on the 10-20 mile scale, where should the tilt be?
A) Anywhere from 10*-15*

The reason people think the RJ's RADAR "sucks" is because they don't know how to use it. We followed company the other day, 2000' below them. They didn't know how to use the RADAR and actually asked for a round about way around the weather in front of them that would've put them in a worse position because they were over painting a level 2 storm.

Landing in PHL the other day, ATC says "you'll go thru a level 3/4 return but the rides have been smooth, it's over the OM".

OK if this was really a level 3/4 return WE SHOULD NOT BE GOING THRU IT! It was a level 2 return.

For those who care the level 3 returns (red) start at 40 decibels. So compare your favorite online RADAR source with the 40 dbz returns and you can correlate what you are seeing out the window with what is being returned by ground based RADAR. The "red" on the NOAA/NWS site (NOAA's National Weather Service) actually is a higher level red than you will see in the cockpit.

Not sure about other RJ's but the limit on the CRJ-200 RADAR dish is around 45 miles or so to depict an accurate VIP level at altitude. This is due to the pickup of ground clutter, which can clutter up the display.

For bonus points what's the quickest way to determine if you are painting a city vs. a cell in the distance?

Airsupport

yes you dont want to over paint either. i guess i could explain a little more. once you start to paint a cell and you see it leaving the ground clutter and moving towards the plane then you can adjust the tilt up and see exactly how high it is. but then again if i am flying into memphis and all i see are a bunch of magenta blobs i will leave the radar where it is at and fly around them. i am really not interested in seeing which ones i dont need to go around. and we have had a lot of magenta blobs lately down here.

and for your bonus question i am going to say go to the mfd menu, select airports, and then if there is an airport where you are painting red then its probably ground clutter or a city.

fosters

I disagree precip held in the cloud by updrafts will still paint even if it is not falling.

Any storm that is worth going around will paint red at the FL250 level regardless if it is raining below it or not.

fosters

Yes you are 100% right. But sometimes you have to make a choice. You need to know what you can go through. Case in point, the "level 3/4 storm" over the OM in PHL. If someone won't go through a level 3/4 at altitude why would they go through it at 2000' AGL?

Yes that works, but easiest way is cities don't attenuate. With your way there might still be a cell on top of the airport/vor !

BoilerUP

Business & Commercial Aviation - "Using Weather Radar to Counter FL Cells"

I consider myself a reasonably smart guy, but I've never understood the Trammel method of doing mental mathematics to use a radar while you're busy flying an airplane.

The guy who taught me how to use airborne radar and had a Ph.D in synoptic meteorology did understand it though...but didn't use that method while flying.

Radar usage is mostly technique, and there is no "wrong" way to use it as long as you're avoiding the worst of the weather.

fosters

It takes a split second to do the math. It's very easy once you know how to do it. I'm curious what method your mentor used, more so because I like to expand my knowledge on the subject, not because I am calling you out. Feel free to PM if you want.

Of course not, you are 100% correct. The issue comes up when you are down in the thick of it shooting approaches. If you are overpainting the cell you might divert for no reason, costing hundreds or thousands in fuel costs alone. It's important to understand the science behind it IMO.

Or in the majority of cases people assume the RADAR "sucks" and go through the storm cell. One day they'll do that on a true storm and get the crap kicked out of them (and that is if they are lucky). The boy who cried wolf comes to mind.

filejw

You guys sure that about Flightware history . My son was going into BNA a few days ago and complained about a lot of turbulence and lighting in a TRW. The A/C then diverted into BHM...i check the flight out using Flightware it it looks like somebody drove him through a line...nice

BoilerUP

The radar on Flightaware does not accurately represent the actual weather an airplane works its way through along a flight.

There have been more times than I can count when, after landing, it shows me having gone head-long through a long line of weather when I was 40 miles in front and paralleling it.

bertengineer

I used to fly for PEANUCKLE before I grew up and got a real job. I heard this about a month ago on the radios..

Center: "Flagship slow to 250"

Flagship: "Ah, center stand-by, we have to get the books out for that one"

Center: "Flagship, are you saying you cannot fly 250?"

Flagship: "Sir, we have to see if we can fly that slow in the books!"


No kidding!
Way to sound professional Flagship, by the way, what is your recommended holding speed above 15000ft IAW the FOM, 225 knots? Also you could use Ref + 40 to figure out slowest speed, keeping within the stall margins...something like that?