We are required to teach a method for estimating thunderstorm cell height using the weather radar. The method IMHO is more inaccurate than simply looking out the window if in daylight.

[gnd return at distance = to height in feet, move up 10 degrees to establish perpendicular beam position, find cell, examine chicken entrails, x .20 % equal cell height....)

Do any other carriers still teach this? Is so why? (I am trying to make a case to delete this from our program)

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).

True... On the mini bus it’s praticaly impossible to safely over fly CBs anyway...

Why would you need to know the top of a cb; to compare with the forecast, interest, etc.

You should be planning how best to avoid the area, never contemplate going over it. If there are red returns, or even a large area of yellow from a radar scan at your level then the avoidance margin should be increased. Red returns indicated a storm above your level, yellow, similar and / or water-ice outflow, both conducive to ice crystal icing - associated with large storms.

Use the radar to assess the shape and extent of the storm and any others around it, which way is it moving, direction of the anvil - avoid going under that. Compare these with the expectation based on the forecast, generate and assess options for action; choose the safest.

Use your time to plan ahead instead of playing with some math formula or rule of thumb.

#1, why not ask ‘why do we need to teach angle / height / range relationships in conjunction with cbs’; what bad habits might be formed, negative training.
Just as much learning value in checking altitude / range from coast lines, etc, or angle - range cross track avoidance distance which is of much more value.

I was the checkee on a line check and the checker tried to impress me with his magic numbers estimating the height of a CB ahead. I looked at him and said I didn’t give a f..k about his estimate, we’re going around it no matter what you say.