Originally Posted by
dweeks
What I don't like about the radar tilt formula for estimating cell heights is that it only sees the top of the radar return.
You can plan on getting your butt severely kicked in the turbulent cloud tops above the highest radar return that don't show on radar.
Our formula is to add 20 percent to the outcome. As an exercise to understand the operation of the weather radar, I can see it has some value. Beam width, the importance of tilt management (most of our control heads don’t have auto tilt) I teach it because I must, but I advocate against its use operationally.
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- Parallel beam position, estimating cell height
- EVALUATING CELL HEIGHT
- Useful only for determining the relative severity of storm
- Should not be used to attempt overflight in IMC.
- Radar height is not the storm height, due to low reflectivity in the cell tops. Assume the actual storm top is at least 20% above the measured radar top. Severe turbulence can exist well above the actual top.
- Tilt - Adjust to parallel beam position
- Adjust the tilt to paint the ground stripe at a range equal to current AGL altitude
- (e.g., flying at FL 370 over sea-level terrain, paint it at 37 NM; at FL 370 over Denver, paint it at approximately 32 NM):
- Increase tilt 10 degrees from previous step
- Determine cell height
- Increases tilt until echo disappears.
- Distance to echo x 100 x degrees of tilt change =
- Radar height of storm above current flight level
- e.g., an echo at 40 NM disappears with a 4° tilt increase: 40 x 100 x 4°= radar top, which is at least 16,000 feet above current flight level; actual top is 120% of 16,000 feet or at least 19,200 feet above current flight level).