The summer Icelandair timetable, does show the flights arriving at 17:30 and departing the next day at 16:30.
Flights depart Reykjavik on Mondays, Wednesdays, Fridays, and Saturdays between 28 Mar 10 and 30 Oct 10. There’s an additional flight on Tuesday between 11 May and 11 Sep. The additional flight between 12 Sep and 30 Oct is on Sundays.
In order of probablity, here’s what I think happens:
The aircraft are based at Reykjavik. Due to crewing issues, the aircraft do spend nearly 24 hours in Seattle for crew rest.
The aircraft is (are) based at Seattle.
The aircraft is (are) based in Reykjavik and have maintenance performed on them while at SEA.
Maybe not 23 hours but it’s not unusual for aircraft to be parked for a long time between flights on European/Far East services. This is due to time slot issues. Ditto for flights between Europe and southern Africa.
And it seems Qantas parks its aircraft at LAX for most of the day. If I’m not mistaken, many of their flights arrive in the early morning and depart late at night.
Yes QF does that and also at London. I think that’s also because of curfew issues or to avoid middle-of-the night arr/dep. I can’t see Icelandair having the same problem which in any case could be avoided by just a slight modification to the BIK-SEA schedule. Plenty of slots at both places.
Icelandair spends a lot of time on the ground in Orlando, also. The flights arrive at 20:55 on Tuesday and Friday. They depart at 19:00 on Wednesday and Saturday. (These flights operated 28 Mar-30 Apr and 25 Sep-30 Oct per the Summer 2010 timetable.)