Route reliability record
SLC→ONT
Salt Lake City to Ontario
- Flights
- 1,239
- Period
- September 2025 to August 2026
- Distance
- 558 mi
- Carriers
- 3
This route earns an A+. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 12 points better than the national rate of 77.3%. When something does go wrong the average delay runs about an hour. That rests on 1,239 SLC to ONT flights, with a median arrival 9 minutes early.
Best time to fly SLC to ONT: a 8am–11am departure, ideally on a Tuesday. Flights in that window arrived on time 94.4% of the time and Tuesday flights 92.1%, against 88.9% for the route overall.
Set against the rest of the country, this route's record is 12 points better than the US average of 77.3%. That gap is worth roughly 116 fewer late arrivals for every thousand flights.
Key figures
On time
88.9%
Arrivals under 15 minutes late, of 1,228 completed flights
Avg delay
61 min
Across delayed arrivals only, not all flights
Cancelled
0.89%
National rate is 1.89%
Best carrier
Delta
87.1% on time across 869 flights
These figures cover 1,239 flights between September 2025 and August 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.
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Carrier by carrier
Which airline is most reliable on SLC to ONT
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlinesthin sample | 340 | 93.2% | 62 min | 0.29% | A+ |
| Frontier Airlinesthin sample | 30 | 93.1% | 101 min | 3.33% | A− |
| Delta Air Lines | 869 | 87.1% | 60 min | 1.04% | A |
Flight by flight
Flights on SLC to ONT
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
Best ways to make this trip
The most reliable ways to fly Salt Lake City to Ontario
Every airline on this route and on the routes between nearby airports, ranked by how often a scheduled flight actually operated and arrived on time. 5 of the top 5 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. SLC → LGBSalt Lake City to Long Beach | SkyWest Airlines | 92.7% | 92.7% | 0.00% | 2pm–5pm, Mon | OO 3793 15:05 |
| 2. SLC → LAXSalt Lake City to Los Angeles | SkyWest Airlines | 91.1% | 91.1% | 0.00% | 5pm–8pm, Wed | — |
| 3. SLC → BURSalt Lake City to Burbank | SkyWest Airlines | 90.4% | 90.9% | 0.53% | 5am–8am, Tue | OO 3693 15:00 |
| 4. SLC → LAXSalt Lake City to Los Angeles | Frontier Airlines | 89.1% | 90.0% | 1.05% | 8am–11am, Tue | — |
| 5. SLC → LGBSalt Lake City to Long Beach | Delta Air Lines | 87.4% | 88.2% | 0.94% | 11am–2pm, Fri | DL 1116 11:05 |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
Departure window
The best time of day to leave
Departure time is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 1,239 flights.
- 5am–8am—
- 8am–11am161 flights94.4%
- 11am–2pm365 flights85.0%
- 2pm–5pm343 flights90.9%
- 5pm–8pm2 flights—
- 8pm–5am368 flights88.5%
Scale runs 75% to 100%. Rows with fewer than 30 flights show a dash.
The weak window here is the middle of the day, not the evening: 11am–2pm runs 85.0% on time against 94.4% for 8am–11am. That shape usually means a departure bank rather than an accumulating delay, so the recovery later in the afternoon is real rather than noise. The 8pm–5am window is the busiest, with 368 flights scheduled in it.
Explore
Filter SLC to ONT by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On SLC to ONT, the best departure window is 8am–11am at 94.4% on time and the worst is 11am–2pm at 85.0%, a real gap of 9.4 points. All US flights leaving 8am–11am ran 83.9%.
- 5–8am—
- 8–11am94.4%
- 11am–2pm85.0%
- 2–5pm90.9%
- 5–8pm—
- 8pm–5am88.5%
best all US flightsScale 60% to 100%. Cells under 30 flights show a dash.
Across the year
When delays peak on this route
This route's year swings by 13 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.
February is the weak month at 82.0% on time, against 94.7% in May. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. August was the busiest month here, with 118 flights.
Across the week, Tuesday is the strongest day at 92.1% on time and Saturday the weakest at 83.3%, a spread of 9 points.
Delay causes
Why this route gets delayed
Carrier accounts for 63% of the 8,334 delay minutes carriers reported here, and the remaining four split what is left.
- 63%Carrier
- 19%Late-arriving aircraft
- 10%National Airspace System
- 8%Extreme weather
The largest share of delay minutes, 63%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 5,260 of the 8,334 delay minutes reported here. The split is drawn from 8,334 reported delay minutes.
Cancellations are rare at 0.89%, below the national 1.89% 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
Badly late arrivals are rare here: only 3.6% land an hour or more behind schedule, against 8.3% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
The 558 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.
The return leg runs 91.1% on time across 1,239 flights, within 2 points 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 1,239 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.
Work out the risk of missing a connection in ONT after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. May runs 94.7% on time and February 82.0%, a swing of 13 points. If the dates move at all, move them out of February before you think about anything else. 1,228 completed flights over 12 months sit behind that.
Common questions
SLC to ONT questions
How often is SLC to ONT delayed?
About one flight in nine arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 11.1% of the 1,239 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
How reliable is SLC to ONT compared with the rest of the country?
88.9% of flights arrive on time here against a national 77.3%, a difference of 12 points in its favour. That is worth a A+ on this site's grading scale.
What time of day has the fewest delays on SLC to ONT?
The 8am–11am departure window is the strongest at 94.4% on time. The 11am–2pm window is the weakest at 85.0%, 9 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 February delays on SLC to ONT?
February is the weakest month at 82.0% on time, compared with 94.7% in May. Across the year that is 13 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- ONT to SLC — the return legseparate record
- Salt Lake City International (SLC) delay statistics
- Ontario International (ONT) delay statistics
- SkyWest Airlines on SLC to ONT93.2%
- Delta Air Lines on SLC to ONT87.1%
- SLC to DEN, a related route79.0%
- PHX to ONT, a related route76.8%
- SLC to PHX, a related route83.5%
- SkyWest Airlines on-time record93.2%
- Frontier Airlines on-time record93.1%
- Delta Air Lines on-time record87.1%
- The most punctual routes in the US, and the least
- The best time of day to fly, according to 7.05 million flight records
Direction matters. SLC to ONT and ONT to SLC are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.