I have noticed that on every MD-80 flight I have been, I have never heard a high-low chime for a crew to FA call on any of them. I have heard that chime on every Boeing, Airbus, and Lockheed aircraft I have flown on with their respective pink or red light.
I was wondering, is there any particular reason why the MD-80 doesn't have the high-low chime? Was this standard on all McDonnell Douglas aircraft?
Interestingly, I remember flying a CO MD-80 in 2002, and the chimes sounded like those on many Schindler elevators from the 1990s, but still I did not hear any high-low chimes on that flight.