Originally Posted by EvD86

I flew this route in December too .

It's good to realise the aircraft has one of the longest turnaround on KL outstations. This means KL855 is frequently delayed on purpose, because they have an ability to swap aircrafts and send other flights off on time. KL855 often takes the pain of the 777 fleet during the day, since the return flight KL856 can still depart on time if the inbound flight is delayed for hours..

So, mostly, KLM choices deliberately to delay KL855 in favour of other flights.

For example, my return flight ICN-AMS even arrived on time in AMS, even when the inbound flight was delayed for 5 hours or so (was that your flight )..