How to determine radar tilt - T.I.P ?

[tathepilot]

There is a formula to determine the tilt required to paint the base of a cell at your altitude.. The formula uses the antenna size and your altitude...

Does anyone know the formula to determine the 'threat identification position' ?

 

[Princedietrich]

Off the top of my head, I have no clue. But try doing a google search for Archie Trammel, the guy has probably forgotten more about airborne weather radar than all of us combined have ever learned.

Be warned: if you watch one of his videos, keep LOTS of caffeine within easy reach. We're talking serious sleep aid here.

 

[GravityHater]

Here are the notes I scribbled when I was watching Arch describe it. Not sure if it will be comprehensible but give it a try:

USING THE RADAR:
Four Fundamental Tilt Settings:
1. TIP - THREAT IDENTIFICATION POSITION
Bottom of the beam is horizontal or parallel to the earth’s surface
A temporary setting, for use in the terminal area only – ie 6 sweeps.
Use TIP with caution if OAT<0C as frozen tops of TZs don’t show up well – they are only 1/5th as reflective.
Note Alt AGL. Tilt to ground displayed at the 12nm position if at 12000’agl (ie lower edge of beam 10degrees down) Raise tilt 10d from there to get lower edge at horizon.
At low altitudes, TIP needs to be adjusted by raising tilt (after doing the above) to reduce false returns:
4000’ add 1d
3000’ add 2d
2000’ add 3d
Anything that shows up can be a threat (because it is not below you). Does not show anything below your travel.
a)[FONT=&quot] [/FONT]note alt in 00s of feet. Ei 12000’
b)[FONT=&quot] [/FONT]paint ground at ie 12 mi & outwards
c)[FONT=&quot] [/FONT]raise tilt 10 degrees from the last step. Now the bottom of beam is parallel to the ground below. (I think this is for 10d wide radars)

USING TIP:
The Characteristics of Dangerous Returns:

• movement >30kts
• non-oval non-cirular return esp asymetric shape or pendant shape, hourglass shape
• asymmetric gradients
• notching or V or U shape in the return
• hooks and fingers (toronadic) Reflectivity: Tilt Control is key 1. Center the beam at 25,000’ to assess storm strength.
• nm x 100 = # of feet in one degree.
• you can make a chart of distance to echo on bottom, altitude along the side…. Provides the degrees above the calibrated zero setting (CZS) that you need to set the tilt to center it at the 25,000’ level.
• eg fl370 and 20nm range chart says use 6d below CZS.
• IF Red at 25,000’, Severe Thunderstorm (painting that high in a cell means a lot of convection as that is above the fz level.
• Look at the base, if you are descending into this area.