rsrik
Posts: 141
Joined: Mon Oct 20, 2008 10:22 am

Mileage - All Over The Place

Tue Jan 27, 2009 6:08 am

My first post of the year, so Happy New Year.

So, what's the story here:
When I book a SFO - NRT ticket
1. The itinerary my travel agent sends out notes the mileage as 5164 miles
2. When I access the reservation on nwa.com, the mileage is 5131
3. When I am buckled up in the plane, the TV screen says 5109 miles
4. When the mileage credit makes it to my DL Skymiles account it is 5124

What is going on there  Smile !? I can understand #3 above - the TV on the plane is likely based on GPS data, and probably the most accurate. Why are the rest off from each other...?

On the same note, do you guys see this in your travels on other airlines? Sorry if I am bringing up something obvious to all of you. I noticed this just about last week, and verified my upcoming itinerary for this anomaly.
Thanks in advance.
Sri

[Edited 2009-01-26 22:09:40]

[Edited 2009-01-26 22:10:09]
 
utapao
Posts: 546
Joined: Sat Jul 09, 2005 10:19 pm

RE: Mileage - All Over The Place

Tue Jan 27, 2009 6:18 am

Have seen the same for years. GDS shows one number, onboard screens another, GCM shows another obviously, and the mileage credited to your account is different.

The thing I have never quite understood is 1) an airline's website showing one total, but the mileage credited being different, and 2) mileage on the same airline, same city-pairs changing from time to time... DFW-MIA -- 1115, 1121, 1127 FF miles in different years.
Sawasdee khrab!
 
rsrik
Posts: 141
Joined: Mon Oct 20, 2008 10:22 am

RE: Mileage - All Over The Place

Tue Jan 27, 2009 6:26 am

Hmm... I didn't realize that the mileage for same city pairs could also change.
How Sneaky  Smile.
 
Viscount724
Posts: 19071
Joined: Thu Oct 12, 2006 7:32 pm

RE: Mileage - All Over The Place

Tue Jan 27, 2009 6:47 am



Quoting Rsrik (Thread starter):
When I book a SFO - NRT ticket
1. The itinerary my travel agent sends out notes the mileage as 5164 miles
2. When I access the reservation on nwa.com, the mileage is 5131
3. When I am buckled up in the plane, the TV screen says 5109 miles
4. When the mileage credit makes it to my DL Skymiles account it is 5124

5131 is what is known as the IATA Ticketed Point Mileage and is used for fare construction purposes. The actual great circle mileage SFO-NRT is 5124 so it looks like DL uses that number. The IATA mileage varies slightly from the great circle mileage when one or both cities at each end of the sector have more than one airport, as Tokyo does. In that case, the IATA mileage uses a formula that uses a mid-point between the airports serving the city. For example, IATA mileages to/from NYC are calculated roughly to/from the mid-point of JFK/EWR/LGA.

I'm not sure where the 5164 comes from, but if there was service from SFO to HND, the other Tokyo airport, the great circle mileage would be 5160.

I expect different frequent flyer programs may not all be consistent but I think quite a few use the IATA mileages since those are also programmed into their systems for certain fare calculation and accounting purposes.
 
rsrik
Posts: 141
Joined: Mon Oct 20, 2008 10:22 am

RE: Mileage - All Over The Place

Tue Jan 27, 2009 7:50 am

Viscount,
Thanks for the info on IATA practice. Although, I don't understand why they need consider multiple airports in a city. After all, I am not asking for a ticket to 'Tokyo', but specifically to Narita. Accepting that and moving on, I still wonder why they publish that as the actual mileage on the itinerary. And, as Utapao pointed out, it makes little sense that my itinerary on nwa.com does not display the actual mileage that will be credited.

An additional observation to my O/P is, once we reach 10,000 feet, the purser usually makes an announcement which calls the correct mileage ... "In today's flight our WorldPerks members will earn approximately 5124 miles...". I would, at a minimum expect the nwa.com reservation detail to indicate the mileage credited.

By the way, I am not critizing the airline for this. Just wondering out aloud.
Sri
 
rsrik
Posts: 141
Joined: Mon Oct 20, 2008 10:22 am

RE: Mileage - All Over The Place

Wed Jan 28, 2009 6:38 pm

Guys
Due to a technical glitch, my post was offline all day yesterday.
I am still interested in what other people have to say on this. Please respond with anything you may have to add...
Thanks

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