Let s say we want to travel on the 60 degrees south parallel between the 000 meridian and 010 east meridian . On a round earth this distance will be half of the same distance measured at the equator. The formula to calculate distances o. The same latitude is "distance = difference in longitude in minutes x cos of latitude . So the result will be 300 nautical miles. Same distance at the Equator will be 600 Nautical miles. So a llane flying with 300 NM /hr will fly 10 meridians , following the rhumb line( the paralel of latitude) in 1 hour.

Now on the flat earth the distance between 10 meridians on the parallel of 60 South will be double the distance that on the Equator.(1200 NM) Wich would mean that a plane , following the parallel of 60 South , with a speed of 300 Nm/hr , will have to make 4 hrs to cover it.

Now in real life the, if you take the plane and do the distance your self you will make it in one hour.

Can anyone explain to me why in real life at the parallel 60 South you cover 10 degrees of longitude, in one hr, travelling with 300 nm /hr ? And not in 4 hrs?

Again , if you can explain the distances of 10 degrees of longitude between the parallels 60North and 60South? Which one is greater?

I don't need any "ifs" because I have done a similar measurements "in real life". It was a little approximate because it was partly based on my Landcruiser's odometer. Though I do know it was accurate to better than 1% and its measured distances agreed with the GPS distances.

One case is where I drove almost directly from the Ballodonia Roadhouse (at 32.35°S, 123.62°E) to Eucla (at 31.68°S, 128.88°E), both in Western Australia.

The Google road distance calculator shows the distance as 518.6 km via National Highway 1.

The distance along the road was 532 km on both the car's odometer and on the Garmin GPS but I made a short deviation to the Eucla Telegraph Station.

And the direct distance from the Ballodonia Roadhouse to Eucla on Google Earth (or on the Garmin maps) is 503 km.

But the direct distance on the usual North Polar AEP map is 1250 km about 2.5 times the direct distance on either map.

I have numerous other similar examples and the North Polar AEP map is unquestionably wrong when it comes to west-east distances here.