Quote from the FAQ´s at their website:
Why is NAA discontinuing its scheduled service operations beyond May 19, 2008?
What makes NAA's scheduled service operations untenable is the rising cost of fuel, with jet fuel costs increasing 60 percent since 2005. This was a difficult decision, especially in light of the continuing support we have received from the governments and the traveling public in these markets. NAA's modern Boeing 757/767 fleet is in high demand and NAA will redeploy these aircraft profitably in the charter market.
Another one!
.. how far is this gonna get! ... Airplanes belong in the sky! not freking fuel prices!