Airborne Weather Radar Tips
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medicineman
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Airborne Weather Radar Tips
Anyone have any good tips on the proper use of airborne weather radar? Thanks in advance.
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Three Holer
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Disclaimer: I have never flown a piston twin around thunderstorms and this is all based on being in the flight levels. I don't know how much of it is applicable to dodging around down low.
Tip number one: Read the manual for your weather radar and make sure you understand completely what each function and button does. What does STAB do? When will it work? How well does it work?
When using a weather radar, first you need to do a confidence check by generating a return off something. This is either the plane in front of you in the lineup or the ground. Once airborne you shoud make sure you are constantly painting (getting a return) a bit of the ground.
Your radar sends out a cone. The size of the cone is determined by the size of your radar antenna. The larger the antenna, the smaller the cone. Once you know the size of the cone you can figure out at what distance your radar should paint the ground at zero tilt. Then you can be sure what setting on the radar actually gives you a zero tilt.
The single biggest factor in making a weather radar useful is tilt control. Proper tilt control will tell you how bad a storm is, and will make sure that you do not miss danger areas and fly through them while deviating around the storm. Start by painting the ground and work your way up. Develop a picture in your mind of what the storms look like at all levels, not just at your level. Two cells may look the same at your level and be of very different intensity, looking up and seeing which one is taller will immediately clue you in to this.
When looking at your radar screen, laterally stretched out returns are usually ground, round returns are usually thunderstorm cells. Anything that looks different from this can be very dangerous: hooks, elongations, concavities, blank spots behind narrow bands, anything that is not a run of the mill cell can be very dangerous.
Don't forget to keep a clear idea of the big picture. Deviate sooner rather than later and keep looking periodically at longer ranges to make sure that you are not putting yourself into a corner. Use your stormscope if you have one to back up where you think the storm cells are and where they are not.
The above are just a few tips to add to a good grounding in weather radar theory. There is a good book by some US airline guy, i can't remember the name but i will dig it up. First and foremost, study all the material you can and find pictures of typical and not so typical storm returns.
Tip number one: Read the manual for your weather radar and make sure you understand completely what each function and button does. What does STAB do? When will it work? How well does it work?
When using a weather radar, first you need to do a confidence check by generating a return off something. This is either the plane in front of you in the lineup or the ground. Once airborne you shoud make sure you are constantly painting (getting a return) a bit of the ground.
Your radar sends out a cone. The size of the cone is determined by the size of your radar antenna. The larger the antenna, the smaller the cone. Once you know the size of the cone you can figure out at what distance your radar should paint the ground at zero tilt. Then you can be sure what setting on the radar actually gives you a zero tilt.
The single biggest factor in making a weather radar useful is tilt control. Proper tilt control will tell you how bad a storm is, and will make sure that you do not miss danger areas and fly through them while deviating around the storm. Start by painting the ground and work your way up. Develop a picture in your mind of what the storms look like at all levels, not just at your level. Two cells may look the same at your level and be of very different intensity, looking up and seeing which one is taller will immediately clue you in to this.
When looking at your radar screen, laterally stretched out returns are usually ground, round returns are usually thunderstorm cells. Anything that looks different from this can be very dangerous: hooks, elongations, concavities, blank spots behind narrow bands, anything that is not a run of the mill cell can be very dangerous.
Don't forget to keep a clear idea of the big picture. Deviate sooner rather than later and keep looking periodically at longer ranges to make sure that you are not putting yourself into a corner. Use your stormscope if you have one to back up where you think the storm cells are and where they are not.
The above are just a few tips to add to a good grounding in weather radar theory. There is a good book by some US airline guy, i can't remember the name but i will dig it up. First and foremost, study all the material you can and find pictures of typical and not so typical storm returns.
Last edited by ahramin on Tue May 16, 2006 8:44 pm, edited 1 time in total.
Stay away from magenta. Red's kinda bad too.
Buildings and rain reflects, snow doesn't.
Look out the window to make sure what's outside kinda jives with what's on the screen. Sometimes radars fail.
Read a GFA before you go flying.
Buildings and rain reflects, snow doesn't.
Look out the window to make sure what's outside kinda jives with what's on the screen. Sometimes radars fail.
Read a GFA before you go flying.
It's better to break ground and head into the wind than to break wind and head into the ground.
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sidestick stirrer
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TOGA Descent
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Re: Airborne Weather Radar Tips
"ahramin" gave you some excellent advice regarding Airborne Weather Radar. If you'll permit me, I'll expand on it a little.Mr.Navajo wrote:Anyone have any good tips on the proper use of airborne weather radar? Thanks in advance.
Like "ahramin" stated, "Tilt and Gain" are the two functions that you need to master. I'll begin with "Gain". Simply put, leave it in the Auto, Calibrated, or whichever setting your system has that provides that function. I'll explain why shortly.
Next is the issue of "Tilt". Many experienced Radar users don't realize that there is an inverse relationship between the diameter of the Weather Radar Units Antenna and the Diameter of the bean that it creates.
For example, a Transport Category Aircraft typically has a 30 inch antenna, which results in a very precise 3 degree radar beam.
Conversely, a 10 inch general aviation antenna creates a bean that is about 18 degrees. Not very accurate for tilt management. Other sizes in between, have varing inverse size relationships.
To effectively manage “Tilt” - and to make it somewhat simple to do whilst during flight - you should re-familiarize yourself with the old “1 on 60 rule”.
For example, on the Airbus, we have the 30 inch antenna. When I place the antenna tilt to zero, I remember that I have 1 ½ degrees of beam width above the horizon, and 1 ½ degrees below (3 degree beam). 1 in 60 means that – with a 3 degree antenna – I am scanning 9000 feet above and below my altitude at 60 miles. Half of that at 30 miles, and double at 120 miles.
With the antenna at 1.5 degrees up, I am scanning an area from my current altitude, up to approximately 18000 feet above that altitude. Remember, at Zero Tilt,(regarless of antenna diameter) half of the beams diameter is scanning above you, and half is scanning below you.
Now we’ll go back to the gain issue. Normally, gain is used to reduce an “Echoe's” return strength. Typically, you would use it to find the “Least worst” area to penetrate. That said, allow me to introduce you to a much better, and safer method.
Leave the Gain in the setting I described earlier. Then, set “tilt” so that you can obtain ground returns on the outer edge of the radar display in the cockpit.
Regardless of the extent of the weather that you are scanning, if you are able to obtain ground returns behind that weather, you now know the TRUE extent of that weather. Many times a “Shadow” will form behind a weather system, thus masking that weathers true extent.
When a “Shadow” occurs, basically all of the radars energy becomes lost in the storm. Again, if there is enough radar energy to penetrate the storm, and then provide a ground return, you have a much better picture of that weather. Basically, that's what the Gain function does, but without knowing exactly how much energy the radar creates in each gain setting, it's not much use to you. The ground return method is much more accurate.
All of that said, my career began in Navajos, so let me offer this final piece of advise. In any light twin, if you really think that you will need to use the radar "pentrate" hazardous weather, DON'T DO IT!
I hope this helps. Again, take "ahramin’s” advise. Thoroughly read the operating manual for the radar unit in your aircraft.
Any questions, feel free to email me. aa321486@yahoo.co.uk
Fly safe!
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Veteran Airbus Crew… "It's doing it again!"
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Jiving on the screen I meen that if there's a cell 40nm off your nose, it's good when you see it on your screen. If it's not there maybe play with knobs until it is. If it still isn't go WAY around.
I've also used weather radar as poor man's gps in the arctic a few times. It's good for knowing when to descend.
Excellent tool when you know what it's telling you
Jiving on the screen I meen that if there's a cell 40nm off your nose, it's good when you see it on your screen. If it's not there maybe play with knobs until it is. If it still isn't go WAY around.
I've also used weather radar as poor man's gps in the arctic a few times. It's good for knowing when to descend.
Excellent tool when you know what it's telling you
It's better to break ground and head into the wind than to break wind and head into the ground.
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TOGA Descent
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A good book on the subject is: Airborne Weather Radar: A User's Guide: Books: James C. Barr
You can order it at:
http://www.amazon.com/gp/product/081381 ... e&n=283155
You can order it at:
http://www.amazon.com/gp/product/081381 ... e&n=283155
Rookie Airbus Crew… "What's it doing now?"
Veteran Airbus Crew… "It's doing it again!"
Veteran Airbus Crew… "It's doing it again!"
I fly a pressurized piston twin with wx radar, and I'm pretty well self-taught on the radar, which likely means I'm doing it wrong. I'm just a dumb airshow pilot, after all.
It's all about the tilt. If you point way up in the sky, there's generally nothing to look at. I might be wrong, but most of the time, the precip is heaviest below (or bottom part) of the cloud. Of course, there are monster exceptions to this.
Run the tilt down until you can see the ground. Raise it up just a smidgeon above that, so the ground returns disappear. They will reappear in turns. There's your starting point for the tilt. Go up from there.
The little radar dishes in light twins really don't work very well, in my experience - their range is quite limited. Combined with the shadowing effect of radar, personally I'd prefer a stormscope, which won't keep you dry, but will keep you out of the bad stuff, and doesn't suffer from shadowing. Costs a tenth as much as radar.
Even better, get an inexpensive garmin 396 w/xm nexrad. Dunno if there's coverage in the glorious People's Republic of Canada yet, but maybe some day there will be, despite the best efforts of the government to thwart it.
It's all about the tilt. If you point way up in the sky, there's generally nothing to look at. I might be wrong, but most of the time, the precip is heaviest below (or bottom part) of the cloud. Of course, there are monster exceptions to this.
Run the tilt down until you can see the ground. Raise it up just a smidgeon above that, so the ground returns disappear. They will reappear in turns. There's your starting point for the tilt. Go up from there.
The little radar dishes in light twins really don't work very well, in my experience - their range is quite limited. Combined with the shadowing effect of radar, personally I'd prefer a stormscope, which won't keep you dry, but will keep you out of the bad stuff, and doesn't suffer from shadowing. Costs a tenth as much as radar.
Even better, get an inexpensive garmin 396 w/xm nexrad. Dunno if there's coverage in the glorious People's Republic of Canada yet, but maybe some day there will be, despite the best efforts of the government to thwart it.
Cessna has a good cd rom for caravan operators and being that you would fly at the same altitudes as they do (and probably have the same or similar unit) you should try to get a hold of a copy.
Some things I remember in particular for it are:
1. Calibrating for zero tilt:
When it is installed it might not be exactly lined up level. To find actual zero tilt while flying, tilt the radar down until it paints ground at a distance in miles equal to your height AGL in feet, ie 5000' AGL = 5 miles.
Next tilt up 10 degrees minus half the beam width (you will have that information in the POH or the radar manual). You probably have a 12" antenna on your bird, which equates to a 8 degree beam width, therefore, up 10 degrees minus 4 = up 6 degrees. Make note of the tilt on the display, this is the calibrated zero tilt for the aircraft.
2. Target identification setting:
This is simply tilting up the extra 4 degrees so that the bottom of the beam is parallel to the flight path. Of course once you start painting targets, you can adjust the tilt to look up and down the cell. Using some rules of thumb like the one in 60 rule etc. you can estimate cell tops and that sort of thing (or use trig if you really want to SOH CAH TOA).
3. VP (Vertical Profile)mode:
If you're lucky enough to have it, which you do if you have the unit I think you do will make target interpretation substantially easier. Start off in normal wx mode and identify targets. When you are painting one, slew the track bar on the radar onto the centre of the target and then press VP to look at the vertical profile of the target.
I should start off by describing how vertical profile works. When you press VP mode, the radar tilts up and down 30 degrees (15 up and 15 down) along the selected track line. If there are no targets, ie wx then you will see a symmetrical ground return (magenta in the middle with red, yellow, then green towards the outside on either side. If you are painting a target then the display will be asymmetrical with lobes on the top of the ground return. Notice the height of the aircraft in relation to the ground return and any wx returns.
Hope that helps. I've used the same radar (radar 2000) in three airplanes (Navajo, Caravan and Pilatus), it seems to be one of the most common for smaller aircraft.
Some things I remember in particular for it are:
1. Calibrating for zero tilt:
When it is installed it might not be exactly lined up level. To find actual zero tilt while flying, tilt the radar down until it paints ground at a distance in miles equal to your height AGL in feet, ie 5000' AGL = 5 miles.
Next tilt up 10 degrees minus half the beam width (you will have that information in the POH or the radar manual). You probably have a 12" antenna on your bird, which equates to a 8 degree beam width, therefore, up 10 degrees minus 4 = up 6 degrees. Make note of the tilt on the display, this is the calibrated zero tilt for the aircraft.
2. Target identification setting:
This is simply tilting up the extra 4 degrees so that the bottom of the beam is parallel to the flight path. Of course once you start painting targets, you can adjust the tilt to look up and down the cell. Using some rules of thumb like the one in 60 rule etc. you can estimate cell tops and that sort of thing (or use trig if you really want to SOH CAH TOA).
3. VP (Vertical Profile)mode:
If you're lucky enough to have it, which you do if you have the unit I think you do will make target interpretation substantially easier. Start off in normal wx mode and identify targets. When you are painting one, slew the track bar on the radar onto the centre of the target and then press VP to look at the vertical profile of the target.
I should start off by describing how vertical profile works. When you press VP mode, the radar tilts up and down 30 degrees (15 up and 15 down) along the selected track line. If there are no targets, ie wx then you will see a symmetrical ground return (magenta in the middle with red, yellow, then green towards the outside on either side. If you are painting a target then the display will be asymmetrical with lobes on the top of the ground return. Notice the height of the aircraft in relation to the ground return and any wx returns.
Hope that helps. I've used the same radar (radar 2000) in three airplanes (Navajo, Caravan and Pilatus), it seems to be one of the most common for smaller aircraft.
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medicineman
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Is the tilt set relative to the airplane, or relative to the deck angle the aircraft generally has in cruise? For example, if your aircraft flies in cruise with a 3 deg nose high deck angle, does zero tilt mean that the radar is pointing 3 degrees up as well? Or is this compensated for during installation, so that during cruise, zero tilt is in fact scanning the actual horizon?
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