Verb
fly under the radar (third-person singular simple present flies under the radar, present participle flying under the radar, simple past flew under the radar, past participle flown under the radar)
(idiomatic) To go unnoticed, especially for a long period of time.
A lot of shows fly under the radar for the first couple seasons and then become successful. It doesn't necessarily have any bearing on the success of the show or how much the network is behind it. Katee Sackhoff
I like to fly under the radar. Lynsi Torres