it's... SKY KING! Neeeeeeooooooowww (plane diving behind announcer's voice) I saw this show when I was a kid - around 5 yrs. old. The shows were syndicated releases shown on my local station. It was around 1959 or 1960 and the series had debuted in 1951. I don't remember much about the shows, other than Sky King wore Western Wear, Penny had blonde hair and they flew around in a plane looking for lost people and stopping baddies from doing dastardly deeds.
I liked the plane, a Cessna T-50 named Songbird, but I was a little more impressed with jets at the time.
Sky was friendly and Penny was "Golly-gee-whiz." It was a good show as I remember it.