Is the flight to London turbulent?
Cruise is smooth most of the way, but transatlantic flights to London cross the North Atlantic jet stream, the busiest CAT hotspot on Earth. Clear-air turbulence is most likely in winter. Approaches into Heathrow and Gatwick can be gusty when Atlantic low-pressure systems bring strong surface winds.
When is the smoothest time to fly to London?
May through September generally has a weaker, more northerly jet and calmer air. Winter (November–March) brings the strongest jet stream and the most clear-air turbulence, plus frequent windy approaches into the London airports.
Why is there turbulence over the Atlantic?
The North Atlantic jet stream — a fast river of air at cruise altitude — creates wind shear at its edges that can jolt an aircraft without warning (clear-air turbulence, or CAT). It is strongest in winter and on the eastbound US→Europe leg, which rides the jet. Pilots change altitude to find smoother air, but CAT is invisible on radar, so it is the main reason to keep your belt on.
Where should I sit on a flight to London?
Over the wing, near the aircraft's center of gravity, gives the steadiest ride. Keep your seatbelt fastened even when the sign is off — clear-air turbulence over the Atlantic can appear suddenly. Overnight eastbound flights often cross the jet stream while you are sleeping, so belt over the blanket.