Carrier route record

F9SEA→PHX

Frontier Airlines · Seattle to Phoenix

Flights: 165
Period: July 2025 to June 2026
Share of route: 2%
Carriers: 7

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Frontier Airlines.

Frontier on SEA to PHX sits in the middle of the pack with a C−. About seven flights in ten arrive on time by the DOT's definition, 7 points worse than the national rate of 77.6%. The late ones land about 2.1 hours behind schedule. That rests on 165 flights. The strongest carrier on the route with a full sample, Envoy Air, flew 691 at 86.9% on time.

Envoy Air is the most reliable of the five carriers covered here at 86.9% on time across 691 flights.

On time

70.4%

Arrivals under 15 minutes late, of 159 completed flights

Avg delay

126 min

Across delayed arrivals only, not all flights

Cancelled

3.64%

National rate is 1.81%

Whole route

79.2%

Every carrier on SEA to PHX, 7,268 flights

These figures cover 165 flights between July 2025 and June 2026. Beyond the headline rate, 10.7% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.

Carrier by carrier

Frontier against every carrier on SEA to PHX

Frontier flew 165 of the 7,268 flights on SEA to PHX, about 2% of it. Its 70.4% on time is 9 points worse than the route as a whole, which runs 79.2%. Ranked by on-time rate it is number six of seven carriers on the route, where the range runs from Envoy at 86.9% to Southwest at 69.0%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.

The choice of carrier is not cosmetic here. Envoy Air arrives on time 86.9% of the time; Southwest Airlines manages 69.0%. Sample sizes sit next to every figure, because a two-point gap across 1,036 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	691	86.9%	71 min	0.00%	A+
American Airlinesthin sample	199	84.8%	81 min	0.50%	B+
Delta Air Lines	1,765	82.6%	65 min	0.85%	B+
SkyWest Airlines	506	80.2%	75 min	0.59%	B+
Alaska Airlines	2,906	79.0%	45 min	0.65%	B+
Frontier Airlines (this page)thin sample	165	70.4%	126 min	3.64%	C−
Southwest Airlines	1,036	69.0%	47 min	0.68%	C+

The spread between Envoy and Southwest is 18 points, wide enough that it should decide the booking. On a hundred trips that is 18 more arrivals inside the on-time window.

Departure window

When Frontier runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 20 points, against 18 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am—
8am–11am—
11am–2pm48 flights76.6%
2pm–5pm5 flights—
5pm–8pm41 flights56.1%
8pm–5am71 flights72.7%

Scale runs 50% to 80%. Rows with fewer than 30 flights show a dash.

The 5pm–8pm window is where this operation falls apart: 56.1% on time, against 76.6% for the 11am–2pm slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 8pm–5am window is the busiest, with 71 flights scheduled in it.

Across the year

Frontier on SEA to PHX through the year

Jul–Sep 202566 flights68.8%
Oct–Dec 202542 flights62.5%
Jan–Mar 202647 flights77.8%
Apr–Jun 202610 flights—

Scale runs 55% to 85%. Rows with fewer than 30 flights show a dash.

Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 70.4% on time across 165 flights.

Frontier on SEA to PHX did not run the same all year. Its best quarter was Jan–Mar 2026 at 77.8% on time and its weakest Oct–Dec 2025 at 62.5%, a swing of 15 points on roughly 55 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.

Across the week, Friday is the strongest day at 65.7% on time and Monday the weakest at 60.0%. 6 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Frontier runs late on this route

One category carries most of the weight here. Late-arriving aircraft accounts for 59% of the 5,930 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.

Late-arriving aircraft
59%
Carrier
36%
National Airspace System
5%
Extreme weather
0%

59% 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 5,930 reported delay minutes here, that single category outweighs weather by 59 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 split is drawn from 5,930 reported delay minutes.

The largest share of delay minutes, 36%, 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 2,127 of the 5,930 delay minutes reported here.

Cancellations run at 3.64%, against 1.81% nationally. That is roughly one flight in 25 cancelled outright. A cancelled flight is invisible in every on-time figure on this page, so the punctuality numbers above describe only the flights that actually operated.

Connections and stage length

What a delay here costs

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 10.7% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.

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 86.1% on time across 165 flights, 16 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 16 points of difference.

One caution: this is a thin sample. 165 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.

What to do with this

Booking Frontier on SEA to PHX

Put together: the delay figures matter less here than the 3.64% cancellation rate. A late arrival costs you about 2.1 hours; a cancelled flight costs you the day. Book the 11am–2pm departure so there is still a schedule behind you if it goes wrong, and treat a same-day connection as optimistic. 159 completed flights over 12 months sit behind that.

Where to go next

Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures