Originally Posted by
sokolov
I've checked similar cross-border routes operated by ExpressJet with Emb 135/145: EWR-YQB-EWR and EWR-YUL-EWR. I don't see such large variations in block time there. Actually, in YUL, the mid-morning departure 10:37 am has a bit longer block time than the early morning and afternoon departures.
The wind doesn't affect north-south routes as much, so the flight time is probably similar. EWR to YQB and YUL are almost due north and much shorter than it is to YHZ. United and others uses historical data to publish block times. The afternoon is almost always more congested at EWR, hence the longer block times. It all comes down to the algorithms they use.