Best airline from Washington to Seattle
Most punctual on this route
79.74% on time across 688 flights · 0.58% cancelled
That is 2.6 points clear of Delta Air Lines, the next best on this route at 77.18%.
Every airline on IAD to SEA, ranked
| # | Airline | Flights | On time | Cancelled | Grade |
|---|---|---|---|---|---|
| 1 | United Airlines | 688 | 79.74% | 0.58% | C |
| 2 | Delta Air Lines | 361 | 77.18% | 1.39% | C |
| 3 | Alaska Airlines | 835 | 73.7% | 1.2% | D |
Why this is worth checking per route
An airline's overall punctuality is an average across everywhere it flies, and averages hide the thing you are booking. A carrier can be middling nationally and the best option on this particular pair of airports — because of which slots it holds, what time of day it schedules, and which aircraft feeds the flight.
On IAD to SEA the spread between best and worst is 6 points. Both carriers fly the same corridor, into the same weather and the same air traffic control — so a gap that size is a fact about the airlines, not the route.
Punctuality is one dimension of a good airline and not the one most people would name first. It is, though, the only one measured the same way for everybody and published by someone with no stake in the answer. Full IAD to SEA record → · Best time of year to fly it →