so let's discuss that in the tech section down below
Aircraft clipping the tops of CB's in IMC and then getting into all sorts of trouble, is a common occurrence world wide. Only the pilots concerned will know why they didn't "see" the offending cloud on their weather radar and for obvious reasons involving legal liability, media interest and job security they ain't gonna talk! While most of the new radars may give give a better "view", at medium altitudes the problem will always exist of low reflectivity of CB tops at high altitudes.
Some Pilot Radar Information Handbooks are supplied with the radar installation. From my experience, these POH are very often not made available to pilots unless they are keen enough to search for them in operator's technical libraries. Occasionally, selected paragraphs from these POH may find their way into company operations manuals. The result is that the art of radar weather interpretation is often a case of learning on the job, with the occasional "mistake" causing broken bones and scared passengers.
Some of the best lessons are learned by "playing" with the radar tilt and Gain controls while looking at isolated CB cells as you pass them by in VMC.
I have no experience of the latest radars installed in the big jets, but believe me, it was the careful use of the variable Gain Control set to max gain in the older radars, that allowed you to pick up the dry tops of big cells and thus warn you of something big ahead and allow time to take whatever action was necessary to avoid the weather.
The Auto or CAL setting of the radar Gain control is not always the optimum setting at high altitudes. If a variable Gain is available, then taking it out of Auto or CAL to the Maximum Gain stop at high cruise altitudes (30,000 to 37,000 ft in the 737 I flew), can often give a tiny "echo" within 40 miles ahead of the top of a CB. But it goes without saying you must know what you are looking for. It appears as a few almost indiscernable dots on the screen - and if you have that dot(s) with zero tilt, then you can be sure there is a big bugger ahead.
If you return to Auto or CAL (depending on the radar type) the echo vanishes and you wouldn't have a clue about what is ahead unless you lower the tilt control. It is the CB top that concerns you because in IMC you can't always "see" it.
You can have all the mathematical calculations you like when talking about tilts and ground returns and so on but I could never remember them anyway. But I do know from long experience that the variable Gain control set to maximum setting at high cruise levels was a life saver on more than a few occasions among seriously nasty areas of CB's.