How can I find the maximum permitted mileage (MPM) between two cities?

Question

Apparently the IATA publishes a list of the "maximum permitted mileage" (MPM) between a large set of city pairs. This mileage is referenced in airline fares.

For example, in order to get an award ticket with a particular itinerary (route) between two points, the proposed route must generally be shorter than the MPM.

Without buying it from IATA, where can I find this list?

Where can I look up the MPM between two particular airports?

Answer 1

The IATA MPM guide is proprietary; I highly doubt they would license a free version for the public.

Fortunately, it looks like a subscription to ExpertFlyer will cover you:

If you're looking to check if a certain routing will be permitted for frequent flyer mile award ticket redemptions, know that the program's/carrier's/alliance's rules will trump what would seem to be permitted by MPM. At this writing, American lets you exceed MPM on an award by 25% and United by 15%, but that may not even matter:

Say you want to fly from San Francisco to Delhi. Using OneWorld carriers, the most direct routing would be to fly from San Francisco to Delhi via Hong Kong…. The problem is that Hong Kong is in “Asia 2″ region while India is in “Indian Sub Continent/Middle East” region, and you can’t transit another region on a partner award.… The MPM between San Francisco and Delhi is 11,922 miles, and American will let you exceed that by 25%, meaning you could fly 14,902 miles. Despite the fact that the routing via Hong Kong is over 5,000 miles under the MPM, it’s still not allowed. (One Mile at a Time blog)

If it's not a miles thing and you're actually constructing complex full fare itineraries for somebody, maybe you should invest in direct GDS (global distribution system) access.