On Oct.23 Tunisia's Syphax Airlines flew a kind of promotional flight to Montreal, Canada on the occasion of an exhibition there and some 140 businessmen and journalists were on that flight.
You can notice that the aircraft didn't follow a NAT route and approaching Iceland it descended from FL380 to FL280. What could be the reason for that ? Flights to Montreal on that day were all on NATs, so why Syphax A330 flew further north on a classic route and why descended ? Does it have to do with MNPS certification ? Or ETOPS ? Or else ? The retour from Montreal on Oct.27 also did the same route back through Greenland and Iceland.