STBYRUD, thanks for your explanation, makes sense to me now...
Spooky 2, it seems to me this is a software issue. I fly often across the Pacific and Polar routes on our B777-300ERs.
Our B777-200s and -300s will only allow a max distance of 511 to be inserted.
Our -300ERs allow up to 999. All our fleet FMCs wont allow NPOLE insertion. The only way around this (for us) is to insert N00E(or W)179 on our FIX page or N000.0E(or W)179.59 on either the FIX or LEGS page.
