Originally Posted by
OskiBear
Here's the link to FlightRadar24 for AA912 (I hope it'll show correctly):
https://www.flightradar24.com/data/flights/aa912
It only goes through April 4th, but shows AA912's scheduled departure each day is 8:40pm and arrival is 4:27am.
So, with DST ending in Chile, it would seem correct that the departure time is going to be an hour "earlier" - even though it's the same time (8:40pm Daylight Saving Time = 7:40pm Standard Time). It appears they are maintaining the arrival time into MIA for 4:27am and just correcting the departure time for the DST to ST change.
Or is my math wrong?
No, I think your math is wrong, because 7:40 PM + 9hr37m would be 5:17 AM.
I counted it out on my fingers several times

7:40 PM, plus 9 hours is 4:40 AM, then the 37 minutes gets you to 5:17 AM.