Rsrik From India, joined Oct 2008, 143 posts, RR: 0 Posted (4 years 4 months 3 weeks 2 days 20 hours ago) and read 2752 times:
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 !? 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
Utapao From Thailand, joined Jul 2005, 645 posts, RR: 9 Reply 1, posted (4 years 4 months 3 weeks 2 days 20 hours ago) and read 2731 times:
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.
Viscount724 From Switzerland, joined Oct 2006, 21679 posts, RR: 23 Reply 3, posted (4 years 4 months 3 weeks 2 days 20 hours ago) and read 2689 times:
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 From India, joined Oct 2008, 143 posts, RR: 0 Reply 4, posted (4 years 4 months 3 weeks 2 days 18 hours ago) and read 2640 times:
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 From India, joined Oct 2008, 143 posts, RR: 0 Reply 5, posted (4 years 4 months 3 weeks 1 day 8 hours ago) and read 2528 times:
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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From India, joined Oct 2008, 143 posts, 
!? 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...?
From Thailand, joined Jul 2005, 645 posts, 
From Switzerland, joined Oct 2006, 21679 posts, 
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