When did that stop? There had to be some criteria for which ones were. Probably on air 24 hours. Do you have pic of it?
Here's a portion of a 1964 Los Angeles Local chart (what's now called a Terminal Area Chart). Several broadcast stations are charted here. It shows KNX 1070 just north of Torrance - a 24/7, 50,000 watt blowtorch that can be heard from a long way away. Just southeast of Van Nuys is KMPC 710 (my favorite station in those days). It was a 24-hour station, but at reduced power after dark. KABC, east of Santa Monica, was a low-power station, only 5,000 watts, I believe. And KDAY 1590 is charted as being "days only".
Surprisingly, KFI 640 is not charted. KFI is the 823' tower just west of Fullerton Airport. I learned to fly at Fullerton, and one was always aware of KFI. The top of the tower was 23 feet higher than the traffic pattern altitude in those days, so one kept bloodshot eyes peeled on smoggy days in the pattern. KFI was a 50,000 watt clear channel station -- with your ADF you could home in on that sucker from Mars. (Cold War-era trivia: KFI was one of the "
Conelrad" stations. Remember AM radios that had the little "CD" logo at the 640 and 1240 spots on the dial?) I grew up just a mile from KFI's transmitter. You could faintly hear KFI programming over the dial tone on our home telephone. My mother swore she could hear it in the fillings in her teeth. KFI carried the Dodgers baseball broadcasts in the '60s and early '70s, so you could listen to Vin Scully's play-by-play as you're cruising all the way back home from Albuquerque. In a slow airplane you could hear the whole double-header.
Remember
Flight Guide, those little brown loose-leaf books chock full of airport diagrams and information? For every airport, Flight Guide listed a nearby AM broadcast station. Came in handy sometimes.
