Route reliability record

SLC→PHX

Salt Lake City to Phoenix

Flights: 5,759
Period: July 2025 to June 2026
Distance: 507 mi
Carriers: 6

This route lands a B+, 6 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 a little over an hour on average. That is a workable record, not a spotless one. That rests on 5,759 flights, of which Delta Air Lines flew 1,708 at 87.9% on time.

Delta Air Lines is the most reliable of the four carriers covered here at 87.9% on time across 1,708 flights.

On time

83.9%

Arrivals under 15 minutes late, of 5,720 completed flights

Avg delay

71 min

Across delayed arrivals only, not all flights

Cancelled

0.56%

National rate is 1.81%

Best carrier

Delta

87.9% on time across 1,708 flights

These figures cover 5,759 flights between July 2025 and June 2026. The median arrival is 9 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 SLC to PHX

The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 87.9% of the time; Southwest Airlines manages 79.6%. Sample sizes sit next to every figure, because a two-point gap across 1,860 flights means less than a ten-point one.

On-time performance by carrier on SLC to PHX
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines	1,708	87.9%	56 min	0.53%	A+
SkyWest Airlines	1,159	86.5%	111 min	0.26%	A+
American Airlinesthin sample	266	84.5%	108 min	0.38%	B+
Envoy Airthin sample	89	81.6%	45 min	1.12%	B
Frontier Airlines	677	81.5%	89 min	1.48%	B
Southwest Airlines	1,860	79.6%	55 min	0.43%	B+

Delta leads Southwest by 8 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

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 17 points, against 8 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am728 flights92.5%
8am–11am945 flights92.1%
11am–2pm1,345 flights86.0%
2pm–5pm922 flights79.2%
5pm–8pm1,032 flights78.0%
8pm–5am787 flights75.9%

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 75.9% for the overnight window. That is 17 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 11am–2pm window is the busiest, with 1,345 flights scheduled in it.

Across the year

When delays peak on this route

Twelve months, one bar each, drawn from the same 5,759 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, November worst

September is the best month on the calendar at 87.8% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. March was the busiest month here, with 582 flights.

Across the week, Tuesday is the strongest day at 87.8% on time and Sunday the weakest at 80.0%. 8 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 48% of the 66,000 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
48%
Carrier
38%
National Airspace System
12%
Extreme weather
2%
Security
0%

48% 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 66,000 reported delay minutes here, that single category outweighs weather by 22 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 65,537 reported delay minutes.

The largest share of delay minutes, 38%, 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 25,000 of the 66,000 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

5.4% 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 a little over 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 83.0% on time across 5,757 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 5,759 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 75.9% on time against 92.5% for the 5am–8am slot, and that 17 points is the largest single thing you control here. Delta Air Lines is the strongest operator if the fares are close. 5,720 completed flights over 12 months sit behind that.

Common questions

SLC to PHX questions

How often is SLC to PHX 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 16.1% of the 5,759 flights in this analysis, against 22.4% nationally. Delayed flights are late by a little over an hour on average.

Which airline is most reliable on SLC to PHX?

Delta Air Lines leads at 87.9% on time across 1,708 flights. Southwest Airlines is at the other end on 79.6%, a gap of 8 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 SLC to PHX?

The 5am–8am departure window is the strongest at 92.5% on time. The 8pm–5am window is the weakest at 75.9%, 17 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 SLC to PHX?

November is the weakest month at 78.5% on time, compared with 87.8% in September. Across the year that is 9 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. SLC to PHX and PHX to SLC 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