Did LAX and ATL airports move 5 miles closer?
Jan 9, 2011, 1:12 am
#1
Original Poster
Join Date: Jan 2008
Location: LAS
Programs: DL PM, UA PS, Hyatt Globalist, Marriott Titanium
Posts: 4,904
Did LAX and ATL airports move 5 miles closer?
Just noticed LAX-ATL flight tomorrow gives 1941 miles. Yet the segment I flew last month was 1946 miles. Going back in my account summary to 2009 shows it was 1947 miles then.
Someone explain this to me please.
I want my 6 (+ medallion bonus) miles back!
Someone explain this to me please.
I want my 6 (+ medallion bonus) miles back!
Jan 9, 2011, 1:32 am
#2
Join Date: Nov 2009
Posts: 1,601
Jan 9, 2011, 6:38 am
#5
Join Date: Dec 2007
Posts: 1,688
They probably changed the software for doing the calculations. There are two things that could cause differences, which might even account for the two changes you saw if they changed each at different times.
The first is fairly understandable: the database listing the exact spot on the earth's surface where the airport is was updated. Airports are pretty big so moving the surveyed location could easily change the calculations by a mile or two.
The second would be if they changed the reference datum for the earth. The earth isn't a perfect sphere, so an ellipsoid is used. But it isn't a perfect ellipsoid either, so you have to map the earths surface onto an ellipsoid to do distance calculations. A very typical reference datum to use is the WGS 84 datum. The FlyerTalk favorite Great Circle mapper uses this datum. But, maybe Delta changed their datum.
The first is fairly understandable: the database listing the exact spot on the earth's surface where the airport is was updated. Airports are pretty big so moving the surveyed location could easily change the calculations by a mile or two.
The second would be if they changed the reference datum for the earth. The earth isn't a perfect sphere, so an ellipsoid is used. But it isn't a perfect ellipsoid either, so you have to map the earths surface onto an ellipsoid to do distance calculations. A very typical reference datum to use is the WGS 84 datum. The FlyerTalk favorite Great Circle mapper uses this datum. But, maybe Delta changed their datum.
Jan 9, 2011, 7:07 am
#7
Join Date: Dec 2007
Posts: 1,688
I'm not sure if this was a joke, but it is almost certainly not the explanation. ATL and LAX both have east-west aligned runways. So they'd have to have extended the runways (considerably) to move the airport survey point by 5 miles.
Jan 9, 2011, 7:26 am
#9
Join Date: Feb 2010
Posts: 96
http://gc.kls2.com/cgi-bin/gc?PATH=k...avy&MAP-STYLE=
This uses the GPS coordinates with the official Airport Reference Points.
This uses the GPS coordinates with the official Airport Reference Points.
Jan 9, 2011, 7:50 am
#10
Join Date: Apr 2002
Location: BOS
Programs: riding the lifetime status. DL MM / AA MM
Posts: 2,968
if you are in the process of booking a flight in the future, and click on the flight number for details, it still says 1946 for ATL-LAX. but, if you look at flight status for a current flight, it says 1941.
looking at something the other direction from ATL -- BOS-ATL is 944 in flight status, and regularly posts at 946. this has been the case for some time..
looking at something the other direction from ATL -- BOS-ATL is 944 in flight status, and regularly posts at 946. this has been the case for some time..
Last edited by Seat1A; Jan 9, 2011 at 8:20 am
Jan 9, 2011, 9:02 am
#12
Join Date: Aug 2010
Location: South Carolina
Programs: Delta FO
Posts: 313
Aren't there official distances used and shared by all carriers for things like maximum permissible miles calculations? I recall looking these up on KVS, and they don't necessarily equal the mileage given in frequent flyer programs.
Jan 9, 2011, 9:05 am
#13
FlyerTalk Evangelist
Join Date: Jun 2006
Location: LAX/BOS/HKG/AMS/SFO...hmm, I need a life.
Programs: United1K, AA ExPlAAt, DL MM/Gold, Hilton Diamond, Avis First
Posts: 13,316
Jan 9, 2011, 9:09 am
#14
FlyerTalk Evangelist
Join Date: Jun 2006
Location: LAX/BOS/HKG/AMS/SFO...hmm, I need a life.
Programs: United1K, AA ExPlAAt, DL MM/Gold, Hilton Diamond, Avis First
Posts: 13,316
I am actually shocked some up and coming accountant has not sold "rounding down" to the powers that be at all the airlines. Just shaving 10 miles from a route has a return of $$$$$$millions across the FF program over a few years.
