Seattle SEA to London Heathrow Flights (SEA to LHR): Nonstop Airlines, Flight Time and Tips

Several nonstop airlines, one seasonal

Seattle to London Heathrow is a nonstop route that follows a northern great-circle path over Canada and Greenland. As of recent schedules, British Airways, Delta and Alaska Airlines fly nonstop between SEA and LHR. Alaska Airlines, Seattle's home airline, added its own daily Heathrow nonstop in 2026. Virgin Atlantic has also flown the route but has paused its Seattle flights for the 2026/27 winter, with plans to return in spring, so check the airline for your dates.

The airlines sit in different partner groups. British Airways and Alaska Airlines are both oneworld members, so their loyalty programmes earn and redeem on each other. Delta and Virgin Atlantic run a joint venture across the Atlantic and sell each other's seats. That gives travellers in either group a nonstop choice.

Connecting itineraries through Chicago, New York, Amsterdam or Reykjavik are also sold, but the nonstop is usually several hours faster door to door.

Route fact	SEA to LHR
Distance	about 4,790 miles (7,710 km)
Eastbound flight time	roughly 9 to 9.5 hours
Westbound flight time	roughly 9.5 to 10 hours
Nonstop airlines	British Airways, Delta, Alaska Airlines (Virgin Atlantic paused winter 2026/27)
Time difference	London is 8 hours ahead of Seattle

Flight time and why the route is shorter than it looks

On a flat map Seattle looks much farther from London than New York does, but the curve of the Earth makes the northern route surprisingly direct. The distance is about 4,790 miles, and eastbound flights typically take 9 to 9.5 hours. The return is a little longer at 9.5 to 10 hours, because the westbound flight faces the jet stream.

Departures range from the afternoon to late evening, landing at Heathrow between the next morning and mid-afternoon. On a clear winter night the route passes over Hudson Bay and southern Greenland, and window seats on the left side going east may catch the northern lights.

Departing from Seattle-Tacoma

Sea-Tac has a single main terminal with several concourses. International departures use a mix of the South Satellite and the main concourses, so check your gate on the day. The International Arrivals Facility handles customs for passengers landing from abroad, which matters on your return.

The Link light rail runs from downtown Seattle and the University District to the SeaTac/Airport station, a short walk across the parking garage to the terminal. It is usually the most reliable way to reach the airport in afternoon traffic on Interstate 5.

Arriving at Heathrow and getting into London

British Airways normally arrives at Terminal 5, while Delta, Alaska Airlines and Virgin Atlantic use Terminal 3. With an approved ETA, most US passport holders can use the eGates.

The Heathrow Express takes about 15 minutes to Paddington. The Elizabeth line runs straight through Bond Street, Tottenham Court Road and the City. If your hotel is near South Kensington or Piccadilly Circus, the Piccadilly line is the direct but slower option.

Eight hours of jet lag

London is eight hours ahead of Seattle for most of the year, and seven hours for short periods in spring and autumn when the two countries change their clocks on different dates. That makes this one of the harder time changes from the US.

Try to sleep in the second half of the flight, when it is night in London. On arrival, get outside in daylight, eat at normal London mealtimes and hold out until a reasonable bedtime. Most people need several days to adjust fully, so plan lighter commitments for your first day.

Choosing between the airlines

Alaska Airlines suits members of its Mileage Plan and travellers starting elsewhere in the Pacific Northwest, since it connects smaller airports such as Spokane, Boise and Portland into its Seattle hub. British Airways lands at Terminal 5, convenient for onward British Airways flights to Europe, and earns oneworld miles too. Delta is the natural choice for SkyMiles members and connects through its Seattle hub, landing at Terminal 3.

If you start your journey outside Seattle, booking the whole trip on one ticket keeps your bags checked through and protects the connection if the first flight runs late.

Entry requirements

US citizens need no visa for short visits to the UK but must have an approved Electronic Travel Authorisation (ETA) before boarding. Apply through the official UK government app or GOV.UK. Canadian travellers who cross the border to fly from Seattle need an ETA as well, and should check GOV.UK for current rules.

When to fly

Summer is the busiest season, with long daylight hours in London and demand from both tourists and the tech industry. Spring and early autumn are quieter and pleasant in both cities. December brings Christmas markets and theatre in London, though days are short. In winter there are fewer nonstop seats on this route while Virgin Atlantic's flights are paused, so book holiday dates early.

Easy things to get wrong

The biggest is assuming every London fare from Seattle goes to Heathrow. Some connecting itineraries land at Gatwick or Stansted, which are farther from the city centre.

The other is the westbound arrival. Flights back to Seattle land in the afternoon or evening, so plan your ride home from the airport around rush-hour traffic or take the Link light rail.