$492 Cheap Flights from Seattle (SEA) to Londonderry (LDY)

View $492 flight on Fri, Jan 23, 2026Opens in a new window

Popular airlines from Seattle-Tacoma International Airport (SEA) to Londonderry (LDY-City of Derry)

Cheap Flights from Seattle to Londonderry (SEA-LDY)

Prices were available within the past 7 days and start at $492 for one-way flights and $913 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

Aer Lingus
Sat, Apr 18 - Sat, Apr 25
SEA
Seattle
LDY
Londonderry
$913 Roundtrip, found 6 days ago
$913
Roundtrip
found 6 days ago
Select Aer Lingus flight, departing Sat, Apr 18 from Seattle to Londonderry, returning Sat, Apr 25, priced at $913 found 6 days ago
Aer Lingus
Sat, Apr 18 - Sat, Apr 25
SEA
Seattle
LDY
Londonderry
$924 Roundtrip, found 6 days ago
$924
Roundtrip
found 6 days ago
Select Aer Lingus flight, departing Sat, Apr 18 from Seattle to Londonderry, returning Sat, Apr 25, priced at $924 found 6 days ago
Aer Lingus
Sat, Apr 18 - Sat, Apr 25
SEA
Seattle
LDY
Londonderry
$933 Roundtrip, found 6 days ago
$933
Roundtrip
found 6 days ago
Select Aer Lingus flight, departing Sat, Apr 18 from Seattle to Londonderry, returning Sat, Apr 25, priced at $933 found 6 days ago
Aer Lingus
Sat, Apr 18 - Sat, Apr 25
SEA
Seattle
LDY
Londonderry
$938 Roundtrip, found 6 days ago
$938
Roundtrip
found 6 days ago
Select Aer Lingus flight, departing Sat, Apr 18 from Seattle to Londonderry, returning Sat, Apr 25, priced at $938 found 6 days ago
British Airways
Sat, Apr 18 - Sat, Apr 25
SEA
Seattle
LDY
Londonderry
$942 Roundtrip, found 6 days ago
$942
Roundtrip
found 6 days ago
Select British Airways flight, departing Sat, Apr 18 from Seattle to Londonderry, returning Sat, Apr 25, priced at $942 found 6 days ago
Aer Lingus
Sat, Apr 18 - Sat, Apr 25
SEA
Seattle
LDY
Londonderry
$944 Roundtrip, found 6 days ago
$944
Roundtrip
found 6 days ago
Select Aer Lingus flight, departing Sat, Apr 18 from Seattle to Londonderry, returning Sat, Apr 25, priced at $944 found 6 days ago
Aer Lingus
Sat, Apr 18 - Sat, Apr 25
SEA
Seattle
LDY
Londonderry
$949 Roundtrip, found 6 days ago
$949
Roundtrip
found 6 days ago
Select Aer Lingus flight, departing Sat, Apr 18 from Seattle to Londonderry, returning Sat, Apr 25, priced at $949 found 6 days ago
Aer Lingus
Sat, Apr 18 - Sat, Apr 25
SEA
Seattle
LDY
Londonderry
$952 Roundtrip, found 6 days ago
$952
Roundtrip
found 6 days ago
Select Aer Lingus flight, departing Sat, Apr 18 from Seattle to Londonderry, returning Sat, Apr 25, priced at $952 found 6 days ago
Aer Lingus
Sat, Apr 18 - Sat, Apr 25
SEA
Seattle
LDY
Londonderry
$954 Roundtrip, found 6 days ago
$954
Roundtrip
found 6 days ago
Select Aer Lingus flight, departing Sat, Apr 18 from Seattle to Londonderry, returning Sat, Apr 25, priced at $954 found 6 days ago
Aer Lingus
Sat, Apr 18 - Sat, Apr 25
SEA
Seattle
LDY
Londonderry
$958 Roundtrip, found 6 days ago
$958
Roundtrip
found 6 days ago
Select Aer Lingus flight, departing Sat, Apr 18 from Seattle to Londonderry, returning Sat, Apr 25, priced at $958 found 6 days ago
Flights from Seattle (SEA) to Londonderry (LDY)
Origin airport
Seattle - Tacoma Intl.
Destination airport
City of Derry
Roundtrip price
$913
Distance
4418 mi

Seattle to Londonderry Flights

The cheapest times to fly from Seattle to Londonderry

On average, Thursday can be the cheapest time to fly, according to data from the Airlines Reporting Corporation (ARC), one of the world's biggest databases for global airline sales. The data reveals that you could save up to 16% by flying on a Thursday—the cheapest day to travel on average—instead of a Sunday—the most expensive. Some of the most affordable flights from Seattle to Londonderry are during the month of April. You can find some of the cheapest flights from Seattle to Londonderry with Expedia's search tool and vast selection of airlines.

 

The best time to book a flight from Seattle to Londonderry

Sunday is one of the best days to book for cheap flights from Seattle to Londonderry: Tickets reserved on a Sunday cost between 6% and 13% less than those reserved on a Friday, according to ARC data. The data also suggests booking early can also lead to cheaper airfares. You could save 24% by buying your tickets for domestic flights at least a month in advance and 10% by booking international flights 2 months in advance.

 

How to find cheap round-trip tickets from Seattle to Londonderry

Being flexible with your dates and using Expedia's Price Drop Protection and Price Tracking features are some of the best ways of finding a cheap ticket from Seattle to Londonderry in 2026. You can also book with separate airlines for your outbound and return journeys, from $492 one-way. Expedia also offers Price Drop Protection, so if the cost of your airfare goes down after booking, you'll receive a credit for the difference*. This is available for a small fee, and is free to One Key Gold and Platinum tier members.

 

Expedia's Price Tracking feature means you can stay on top of airfares without manually checking every day. It sends you automated price alerts for cheap Seattle to Londonderry flights and uses historical data to indicate when the best time to book is. Download Expedia's free app to activate this handy tool in a few easy taps.

 

You could also save big by booking one of Expedia's vacation packages. Bundling together your Seattle to Londonderry airfare with your accommodations and car rental is often cheaper than booking everything separately. There’s also One Key, Expedia's generous rewards program. Join for free and you could earn One Key cash on most bookings to save on future adventures.

 

*Terms apply.

 

Disclaimer: ARC The statistics are based on average round-trip ticket prices between January and August 2023. The percentages you see are averages.

 

Frequently asked questions

How much does a flight from Seattle - Tacoma Intl. Airport (SEA) to City of Derry Airport (LDY) cost?
Get a cheap one-way flight from $492 or cheap return flight from $913 from Seattle - Tacoma Intl. Airport (SEA) to City of Derry Airport (LDY) with Expedia. Enter your travel dates and sort by "Price (lowest to highest)" to see our cheapest flight offers on this route.
What is the cheapest month to fly from Seattle - Tacoma Intl. Airport (SEA) to City of Derry Airport (LDY)?
Flying in April is a great way to save, as it's the cheapest month for flights between SEA and LDY. You'll usually find the lowest fares during off-peak months.
What is the cheapest airline that flies from Seattle - Tacoma Intl. Airport (SEA) to City of Derry Airport (LDY)?
Expedia's filter tool lets you easily compare travel time, airlines and fares all in one place. Tailor the search to your trip, then sort by "Price (lowest to highest)" to find out which carrier offers the cheapest SEA to LDY flight.
How many flights per day from Seattle - Tacoma Intl. Airport (SEA) to City of Derry Airport (LDY)?
You'll need to take a flight with a layover if you're traveling from Seattle - Tacoma Intl. Airport (SEA) to City of Derry Airport (LDY). Direct flights don't operate daily on this route. However, simply filter your search to include one or two stops to find an option that works for you.
What day of the week has the most flights from SEA to LDY?
Friday is generally the busiest day for flights, while Tuesday is often the quietest.* Keep in mind that flight schedules can change depending on a range of factors, such as the season and airline.*Busiest/quietest day to travel is based on Expedia flight demand through January to December 2024.
What is the best time to fly from Seattle - Tacoma Intl. Airport (SEA) to City of Derry Airport (LDY)?
Book a flight from Seattle - Tacoma Intl. Airport (SEA) to City of Derry Airport (LDY) that takes off before 3 PM to reduce the risk of cancellations. Departures after this hour are on average 22% more likely to be canceled.**Most reliable time of the day and month to travel recommendation is based on January through August 2024 flight status data sourced from OAG's global flight data platform.
Is it cheaper to buy a plane ticket from Seattle - Tacoma Intl. Airport (SEA) to City of Derry Airport (LDY) last-minute?
Booking your ticket from SEA to LDY shortly before your getaway is generally more expensive. However, if there's some wiggle room with your itinerary, you could grab a cheap last-minute fare.
Is it cheaper to book a SEA to LDY flight and hotel package?
You can save money by booking a SEA to LDY flight and hotel package compared to booking separately. In fact, you could save hundreds of dollars by bundling with Expedia. And it's simple to manage it all in one convenient place. Once you've chosen your ideal flights and accommodations, consider adding extras including activities, car rentals and tours.
Can I cancel or change the date of my flight from Seattle - Tacoma Intl. Airport (SEA) to City of Derry Airport (LDY)?
In most instances, you're able to reschedule or cancel your SEA to LDY flight. However, there may be additional charges, especially if you made your booking more than 24 hours ago. Double-check your itinerary for the airline's fees and policies on flight changes, or if you'd like more details, go to our Customer Service portal.

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*Available to One Key members.