In fact, flights overall were for the most part very punctual, according to data compiled by turisti.is
. Of the 407 flights which flew from Keflavík to other countries in the latter part of September, only 24 were late, meaning 94% of these flights were on time.
Of all the airlines, Iceland Express was the most punctual. Only one in 43 departures at that airline were delayed. At WOW Air, all 13 of their flights were on time. At Icelandair, their flights were on time about 90% of the time.
Turisti.is, among other things, tracks the daily punctuality of arrivals and departures for different airlines.
Of the different airlines coming in and out of Keflavík International Airport, Iceland Express proved the most punctual of them all.