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Flight time and departure/arrival time don't add up (AA912 SCL-MIA)

Flight time and departure/arrival time don't add up (AA912 SCL-MIA)

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Old Mar 26, 19, 1:48 pm
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Flight time and departure/arrival time don't add up (AA912 SCL-MIA)

I am scheduled in AA912 SCL-MIA on April 9. DST ends on April 7th in Chile and they move clocks back an hour, putting them at UTC-4, matching Miami who is also UTC-4. If my math is correct, and I've double and triple checked it, since the flight is within the same time zone, if it departs at 7:40 PM and takes 9hr37m, it would arrive at 5:17 AM in Miami, not 4:17 AM. They are off by an hour somewhere.

Obviously, I'm hoping that the arrival time is wrong, and I'm arriving at 5:17 AM in MIA, which cuts my layover to 3 hours instead of 4. I assume no matter what, the departure time is correct and it's not really departing at 6:40 PM. I hope that assumption is correct?

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Old Mar 26, 19, 2:29 pm
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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?
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Old Mar 26, 19, 2:43 pm
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Originally Posted by OskiBear View Post
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.
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Old Mar 26, 19, 2:44 pm
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Dep and Arr times are correct as listed. DST in SCL ends on 4/7. SCL moves from UTC-3 to UTC-4 when DST ends, effectively matching MIA (UTC-4) at that point. Proper flight duration should be 8:37.
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Old Mar 26, 19, 3:06 pm
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Originally Posted by ntamayo View Post
Dep and Arr times are correct as listed. DST in SCL ends on 4/7. SCL moves from UTC-3 to UTC-4 when DST ends, effectively matching MIA (UTC-4) at that point. Proper flight duration should be 8:37.
That's what is throwing OP off - the flight duration listed as 9hours 37minutes when it's actually 8hours 37minutes
If you look at the FightRadar24 link I provided, most flights are clocking in at just under 8hours.

So, all of our math is correct, it's AA's math that is bad :-)
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Old Mar 26, 19, 3:11 pm
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Originally Posted by ntamayo View Post
Dep and Arr times are correct as listed. DST in SCL ends on 4/7. SCL moves from UTC-3 to UTC-4 when DST ends, effectively matching MIA (UTC-4) at that point. Proper flight duration should be 8:37.
Originally Posted by OskiBear View Post
That's what is throwing OP off - the flight duration listed as 9hours 37minutes when it's actually 8hours 37minutes
If you look at the FightRadar24 link I provided, most flights are clocking in at just under 8hours.

So, all of our math is correct, it's AA's math that is bad :-)
Ahhh, there’s where that extra hour comes from, thanks!

As a software developer, I can’t really fault them. Time zones and DST are the bane of our existence
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Old Mar 26, 19, 3:17 pm
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Especially when inconsistent. On a trip between Chile and Argentina around 2010 or so, after the earthquake, Chile had imposed a different DST timeline than before. It was havoc flying between the two countries as I was always unsure whether I’d be late or super-early for a flight.
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Old Mar 26, 19, 3:41 pm
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Originally Posted by t325 View Post




Ahhh, there’s where that extra hour comes from, thanks!

As a software developer, I can’t really fault them. Time zones and DST are the bane of our existence
Fun for navigation too.... especially when combined.... lol. Having three DR positions in a row all marked with the same time is a bit surreal....
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Old Mar 26, 19, 7:53 pm
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And arrived in Miami the other day at 340 am. We had to wait for immigration to open.
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Old Mar 27, 19, 3:33 am
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This is a common problem with AA and SCL flights twice each year with time change in Chile that something gets messed up for a little while each time the clocks change. As an earlier poster pointed out, the dep/arr times are correct, but the calculation of flight duration is incorrect. (Which is better than in the past when AA suddenly change the departure times by an hour just days before time change to maintain the same arrival times state-side; this time they seem to have planned ahead correctly!)

To be fair to the developers, the date of DST ending changed this year from May to April reasonably recently. When I was looking into this a week or two ago the durations for SCL-DFW were only incorrect between the “new” time change date (weekend of April 7) and the “old” time change date in May. After that durations were correct.
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Old Mar 27, 19, 3:34 am
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Originally Posted by C17PSGR View Post
And arrived in Miami the other day at 340 am. We had to wait for immigration to open.
SCL-DFW regularly arrives right as customs opens at 5am. Is not uncommon to have to sit and wait a few minutes for customs to arrive before opening the door.
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Old Mar 27, 19, 10:12 am
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Originally Posted by OskiBear View Post
Especially when inconsistent. On a trip between Chile and Argentina around 2010 or so, after the earthquake, Chile had imposed a different DST timeline than before. It was havoc flying between the two countries as I was always unsure whether I’d be late or super-early for a flight.
Chile actually decides on and publishes their DST/ST dates year by year so there's rarely consistency (it's the Ministry of Energy, to be exact). One year they did away with DST fully, and then reinstated it the next. Most of my flights around those times of year had incorrect in-flight times/dates, schedules were updated at the last minute, etc. I feel the OP's pain.

Last edited by zpaul; Mar 27, 19 at 10:17 am
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Old Mar 27, 19, 11:49 am
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Sorry, OP. You got the flight duration wrong. It takes the same amount of flying between two airports regardless of what the clock says at takeoff or landing.
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Old Mar 27, 19, 12:28 pm
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Sometimes it's better to see the comparison before vs after DST change. Note the O & D time scales are different before DST, but same after DST:



ITA screenshot for flights before and after DST change
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