Miami radar
 

Hi all. OK so, I was flying my qualifying cross country nav flight a couple weeks ago. I was receiving flight following from Miami Center. I was at around 3000ft. Then because of some low cloud I had to descend to below 2000ft to maintain VMC. The Miami Center controller advised me that I was getting a bit low, and asked me if I could maintain a higher altitude. I told him that for the time being I couldn't - because of the cloud. So, he wasn't all too happy I think but nevertheless I was still receiving FF.

Then, on my second leg, I asked for flight following again. They said I was too low to be picked up by the radar and that I would have to be at around 2500ft... This confuses me slightly because I was well bellow 2500ft on parts of my first leg and still visible on radar.

Any thoughts???

Thanks! :)

Simple - think about the range and angles

The radar waves are not parallel to the ground they are at a slight angle typically a couple of degrees.

The further away from the radar the greater the distance between the ground and the lowest radar wave.

The closer you are the smaller the angle.

Miami has several radars that feed into their system - I would imagine on the 2nd leg you were simply further away.

Radar is affected by many factors but range is a basic one.

This is the best image I can find - it's for weather radar but still illustrates the point https://encrypted-tbn1.gstatic.com/i...WtTaiuYfrBKkTw

The other alternative is that the controller didn't have the capacity to control you as VFR - remember in the USA flight following is workload permitting for controllers.

Aha! Makes perfect sense, don't know why I didn't think of that! And come to think of it... the controller did seem very busy as well, (told me to stand-by twice!) but I think I must simply have been too far from the station.

Thanks!!