projections in long range plotting charts
As an academic exercise I am trying to create (in ARCGIS 9.1) some ETOPS plotting charts covering aerodromes from mid to high latitudes. The extremities of two aerodromes are at latitudes 40/42 and the other pair of aerodromes at latitudes 67/78.
I am using a Lambert's Conformal Conic projection, standard parallels of 55 and 65.
The trouble is that the 90 minute range rings between the lat 67 and lat 78 aerodromes are not the correct distance apart on the map due to the projection. ie. I have told it to project a 609nm ring around both airports. The airports are 1144nm apart, but the two 609nm rings do not overlap - they miss by about 30nm.
Any suggestions, other than reduce the extent of the map to try and eliminate this error?
What are real etops charts like in their coverage, and what projections, extents and std parallels are used?
Are there any ETOPS charts that cover this vertical (n/s) extent? Or are ETOPS charts for say LAX-LHR broken down into more bitesize chunks, thus eliminating this problem.
Thanks in advance