Route reliability record

SEA→PHX

Seattle to Phoenix

Flights: 7,317
Period: June 2025 to May 2026
Distance: 1,107 mi
Carriers: 7

This route lands a B+, 2 points better than the national rate of 77.4%. About one flight in five arrive 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 7,317 flights, of which Envoy Air flew 646 at 84.9% on time.

Envoy Air is the most reliable of the five carriers covered here at 84.9% on time across 646 flights.

On time

79.1%

Arrivals under 15 minutes late, of 7,240 completed flights

Avg delay

56 min

Across delayed arrivals only, not all flights

Cancelled

0.70%

National rate is 1.80%

Best carrier

Envoy

84.9% on time across 646 flights

These figures cover 7,317 flights between June 2025 and May 2026. The median arrival is 5 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.

Carrier by carrier

Which airline is most reliable on SEA to PHX

The choice of carrier is not cosmetic here. Envoy Air arrives on time 84.9% of the time; Southwest Airlines manages 71.1%. Sample sizes sit next to every figure, because a two-point gap across 1,035 flights means less than a ten-point one.

On-time performance by carrier on SEA to PHX
Airline	Flights	On time	Avg delay	Cancelled	Grade
Envoy Air	646	84.9%	65 min	0.00%	B+
American Airlinesthin sample	203	84.7%	79 min	0.49%	B+
Delta Air Lines	1,765	83.2%	67 min	0.91%	B+
SkyWest Airlines	547	81.7%	75 min	0.55%	B+
Alaska Airlines	2,930	77.9%	44 min	0.61%	B+
Frontier Airlinesthin sample	191	71.4%	133 min	3.14%	C−
Southwest Airlines	1,035	71.1%	48 min	0.68%	C+

The spread between Envoy and Southwest is 14 points, wide enough that it should decide the booking. On a hundred trips that is 14 more arrivals inside the on-time window.

Departure window

The best time of day to leave

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 21 points, against 14 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am1,284 flights92.5%
8am–11am1,215 flights82.2%
11am–2pm1,576 flights74.7%
2pm–5pm1,395 flights76.7%
5pm–8pm1,183 flights74.4%
8pm–5am664 flights71.5%

Scale runs 65% to 100%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 92.5% of the time, against 71.5% for the overnight window. That is 21 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on.

Across the year

When delays peak on this route

This route's year swings by 15 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.

Darker means more delays. Figures are on-time percentages.February best, November worst

Delays peak in November, when the on-time rate falls to 70.9%. February is the strongest month at 85.8%. Moving a flexible trip across that boundary buys 15 points.

Across the week, Tuesday is the strongest day at 83.0% on time and Monday the weakest at 75.7%. 7 points is a smaller lever than departure hour, but it is free.

Delay causes

Why this route gets delayed

One category carries most of the weight here. Carrier accounts for 45% of the 85,000 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.

Carrier
45%
Late-arriving aircraft
36%
National Airspace System
18%
Extreme weather
1%
Security
0%

36% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 85,000 reported delay minutes here, that single category outweighs weather by 29 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit.

The largest share of delay minutes, 45%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 38,000 of the 85,000 delay minutes reported here.

Cancellations are rare at 0.70%, below the national 1.80% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.

Connections and stage length

What a delay here actually costs

5.0% of arrivals land an hour or more late, close to the national 8.2%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route are the about an hour kind, which a normal layover absorbs.

The 1,107 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.

The return leg is a different operation and performs like one: it runs 82.6% on time across 7,317 flights, 4 points above this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 4 points of difference.

The sample behind these figures is 7,317 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.

What to do with this

Booking this route

Put together: the calendar is the biggest lever here, not the carrier or the hour. February runs 85.8% on time and November 70.9%, a swing of 15 points. If the dates move at all, move them out of November before you think about anything else.

Common questions

SEA to PHX questions

How often is SEA to PHX delayed?

About one flight in five arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 20.9% of the 7,317 flights in this analysis, against 22.6% nationally. Delayed flights are late by about an hour on average.

Which airline is most reliable on SEA to PHX?

Envoy Air leads at 84.9% on time across 646 flights. Southwest Airlines is at the other end on 71.1%, a gap of 14 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.

What time of day has the fewest delays on SEA to PHX?

The 5am–8am departure window is the strongest at 92.5% on time. The 8pm–5am window is the weakest at 71.5%, 21 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.

How bad are November delays on SEA to PHX?

November is the weakest month at 70.9% on time, compared with 85.8% in February. Across the year that is 15 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.

Where to go next

Direction matters. SEA to PHX and PHX to SEA are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.

Source: US DOT Bureau of Transportation Statistics, on-time performance data, June 2025 to May 2026. Updated monthly. How this data is collected.

Key figures