Route reliability record

PHX→SLC

Phoenix to Salt Lake City

Flights: 5,757
Period: July 2025 to June 2026
Distance: 507 mi
Carriers: 6

This route lands a B+, 5 points better than the national rate of 77.6%. About one flight in six 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 5,757 flights, of which Delta Air Lines flew 1,708 at 90.4% on time.

Delta Air Lines is the most reliable of the four carriers covered here at 90.4% on time across 1,708 flights.

On time

83.0%

Arrivals under 15 minutes late, of 5,719 completed flights

Avg delay

61 min

Across delayed arrivals only, not all flights

Cancelled

0.56%

National rate is 1.81%

Best carrier

Delta

90.4% on time across 1,708 flights

These figures cover 5,757 flights between July 2025 and June 2026. The median arrival is 8 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 PHX to SLC

The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 90.4% of the time; Southwest Airlines manages 75.5%. Sample sizes sit next to every figure, because a two-point gap across 1,858 flights means less than a ten-point one.

On-time performance by carrier on PHX to SLC
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines	1,708	90.4%	75 min	0.59%	A+
American Airlinesthin sample	266	86.7%	70 min	0.38%	A+
Frontier Airlines	677	83.6%	78 min	1.77%	B
SkyWest Airlines	1,159	83.1%	67 min	0.26%	B+
Envoy Airthin sample	89	83.1%	46 min	0.00%	B+
Southwest Airlines	1,858	75.5%	48 min	0.32%	B+

The spread between Delta and Southwest is 15 points, wide enough that it should decide the booking. On a hundred trips that is 15 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 28 points, against 15 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am683 flights95.7%
8am–11am1,300 flights88.4%
11am–2pm855 flights85.2%
2pm–5pm1,019 flights81.3%
5pm–8pm1,237 flights78.5%
8pm–5am663 flights67.9%

Scale runs 60% to 100%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 95.7% of the time, against 67.9% for the overnight window. That is 28 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8am–11am window is the busiest, with 1,300 flights scheduled in it.

Across the year

When delays peak on this route

Twelve months, one bar each, drawn from the same 5,757 flights. The strip shows how much of this route's record is set by the calendar rather than by the operation.

Darker means more delays. Figures are on-time percentages.September best, June worst

June is the worst month at 79.3% on time, 7 points below September, the best at 86.6%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. March was the busiest month here, with 581 flights.

Across the week, Tuesday is the strongest day at 88.7% on time and Sunday the weakest at 79.7%. 9 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. Late-arriving aircraft accounts for 52% of the 59,000 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.

Late-arriving aircraft
52%
Carrier
40%
National Airspace System
6%
Extreme weather
1%
Security
0%

52% 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 59,000 reported delay minutes here, that single category outweighs weather by 36 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 58,882 reported delay minutes.

The largest share of delay minutes, 40%, 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 24,000 of the 59,000 delay minutes reported here.

Cancellations are rare at 0.56%, below the national 1.81% 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

5.1% of arrivals land an hour or more late, close to the national 8.1%. 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 507 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 runs 83.9% on time across 5,759 flights, within about a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.

The sample behind these figures is 5,757 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: avoid the 8pm–5am departure. It runs 67.9% on time against 95.7% for the 5am–8am slot, and that 28 points is the largest single thing you control here. Delta Air Lines is the strongest operator if the fares are close. 5,719 completed flights over 12 months sit behind that.

Common questions

PHX to SLC questions

How often is PHX to SLC delayed?

About one flight in six arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 17.0% of the 5,757 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.

Which airline is most reliable on PHX to SLC?

Delta Air Lines leads at 90.4% on time across 1,708 flights. Southwest Airlines is at the other end on 75.5%, a gap of 15 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 PHX to SLC?

The 5am–8am departure window is the strongest at 95.7% on time. The 8pm–5am window is the weakest at 67.9%, 28 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 June delays on PHX to SLC?

June is the weakest month at 79.3% on time, compared with 86.6% in September. Across the year that is 7 points between the best and worst months. The seasonal swing is modest enough that it should not decide when you travel.

Where to go next

Direction matters. PHX to SLC and SLC to PHX 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, July 2025 to June 2026. Updated monthly. How this data is collected.

Key figures