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Finnair AY15 flies the jet-stream + mountain-wave corridor from Helsinki to New York. Conditions change hour to hour — view the live forecast for your departure date.
View live forecastJet-stream exposure on this corridor is significant. Long mid-latitude legs mean clear-air turbulence is the dominant source of bumps, typically encountered at cruise altitude. The route crosses or passes near the Greenland ice cap, which can generate mountain-wave turbulence downwind when upper-level winds are strong. Westbound aircraft typically fly against the prevailing winds, adding flight time. Captains often pick altitudes that avoid the strongest headwinds, which can also mean picking cleaner-air altitudes.
Calmest season: May–September. The North Atlantic track sees its strongest jet-stream activity from November through February, when winds commonly exceed 150 kt and clear-air turbulence is more frequent. Wind flowing over Greenland ice cap can generate mountain-wave turbulence that extends hundreds of kilometres downwind — most pronounced in winter when upper-level winds are strongest.
Full HEL to JFK route guideFinnair AY15 operates between HEL and JFK. Whether it’s bumpy depends on the day’s weather — Turbcast pulls live NOAA aviation-grade data so you can check the actual forecast for your departure date rather than relying on averages.
AY15 is typically operated by the A359. Aircraft swaps happen — confirm with your booking before flying.
Approximately 8h 11m direct, covering 6,607 km at a typical cruise of FL390.
Historically calmest during May–September. Forecast accuracy improves as you get closer to departure — within 48 hours the NOAA WAFS model is at peak skill.