dixi188
Many thanks for those explanations. The bleepy radios appeared on one or two 737s in the 1980s, UK operators, but I can't remember who.
The Court Line fleet had them too of course, frequent diversions from EGGW to EGNX.
Othe great sounds include the Vanguards and the RB162 boost engine on the Trident 3.
Best Wishes to all who designed, built and flew all these amazing- sounding machines.