Route reliability record
DEN→LGB
Denver to Long Beach
- Flights
- 1,005
- Period
- September 2025 to August 2026
- Distance
- 854 mi
- Carriers
- 1
This route sits in the middle of the pack with a C+. About seven flights in ten arrive on time by the DOT's definition, 5 points worse than the national rate of 77.3%. The late ones land roughly 45 minutes behind schedule. That rests on 1,005 DEN to LGB flights, with a median arrival right on schedule.
Best time to fly DEN to LGB: a 8am–11am departure, ideally on a Saturday. Flights in that window arrived on time 90.3% of the time and Saturday flights 79.6%, against 72.7% for the route overall.
The national on-time rate over the same period is 77.3%, so this route runs 5 points behind the country as a whole. Across a thousand flights that is about 46 extra late arrivals.
Key figures
On time
72.7%
Arrivals under 15 minutes late, of 997 completed flights
Avg delay
46 min
Across delayed arrivals only, not all flights
Cancelled
0.60%
National rate is 1.89%
Best carrier
Southwest
72.7% on time across 1,005 flights
These figures cover 1,005 flights between September 2025 and August 2026. On-time means an arrival less than 15 minutes after the scheduled gate time, the same threshold the Department of Transportation uses in its own reports. Cancelled and diverted flights are excluded from the on-time rate and counted separately, which is why the cancellation column matters on its own.
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Carrier by carrier
Which airline is most reliable on DEN to LGB
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 |
|---|---|---|---|---|---|
| Southwest Airlines | 1,005 | 72.7% | 46 min | 0.60% | C+ |
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Best ways to make this trip
The most reliable ways to fly Denver to Long Beach
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. DEN → SNADenver to Santa Ana | United Airlines | 85.2% | 85.3% | 0.16% | 5am–8am, Tue | UA 2666 07:40 |
| 2. DEN → LAXDenver to Los Angeles | United Airlines | 84.0% | 84.0% | 0.00% | 5am–8am, Sat | UA 1638 08:00 |
| 3. DEN → LAXDenver to Los Angeles | Frontier Airlines | 82.8% | 83.4% | 0.75% | 5am–8am, Sun | F9 2341 06:00 |
| 4. DEN → LAXDenver to Los Angeles | Delta Air Lines | 80.1% | 81.2% | 1.34% | 5am–8am, Mon | DL 2002 07:25 |
| 5. DEN → ONTDenver to Ontario | Frontier Airlines | 79.9% | 80.3% | 0.54% | 5am–8am, Sun | F9 1261 22:29 |
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 matters more here than the choice of carrier. The gap between the best and worst window is 30 points, against half a point between the best and worst carrier.
- 5am–8am32 flights75.0%
- 8am–11am300 flights90.3%
- 11am–2pm158 flights69.2%
- 2pm–5pm187 flights67.9%
- 5pm–8pm328 flights60.6%
- 8pm–5am—
Scale runs 50% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 60.6% on time, against 90.3% for the 8am–11am 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 5pm–8pm window is the busiest, with 328 flights scheduled in it.
Explore
Filter DEN to LGB 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 DEN to LGB, the best departure window is 8am–11am at 90.3% on time and the worst is 5pm–8pm at 60.6%, a wide gap of 29.7 points. All US flights leaving 8am–11am ran 83.9%.
- 5–8am75.0%
- 8–11am90.3%
- 11am–2pm69.2%
- 2–5pm67.9%
- 5–8pm60.6%
- 8pm–5am—
best all US flightsScale 50% to 95%. Cells under 30 flights show a dash.
Across the year
When delays peak on this route
This route's year swings by 31 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.
June is the worst month at 55.1% on time, 31 points below January, 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. May was the busiest month here, with 93 flights.
Across the week, Saturday is the strongest day at 79.6% on time and Monday the weakest at 67.6%, a spread of 12 points.
Delay causes
Why this route gets delayed
Late-arriving aircraft accounts for 55% of the 13,000 delay minutes carriers reported here, and the remaining four split what is left.
- 55%Late-arriving aircraft
- 32%Carrier
- 11%National Airspace System
- 1%Extreme weather
- 1%Security
55% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 13,000 reported delay minutes here, that single category outweighs weather by 48 to one. The split is drawn from 12,542 reported delay minutes.
The practical consequence: the 8am–11am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 90.3% on time here.
Cancellations are rare at 0.60%, 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
6.0% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last roughly 45 minutes, which a normal layover absorbs.
The 854 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 is a different operation and performs like one: it runs 82.0% on time across 1,007 flights, 9 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 9 points of difference.
One caution: this is a thin sample. 1,005 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.
Work out the risk of missing a connection in LGB after this flight
What to do with this
Booking this route
Put together: treat all of this as provisional. 1,005 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 72.7% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 997 completed flights over 12 months sit behind that.
Common questions
DEN to LGB questions
How often is DEN to LGB delayed?
Roughly one flight in four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 27.3% of the 1,005 flights in this analysis, against 22.7% nationally. Delayed flights are late by roughly 45 minutes on average.
How reliable is DEN to LGB compared with the rest of the country?
72.7% of flights arrive on time here against a national 77.3%, a difference of 5 points against it. That is worth a C+ on this site's grading scale.
What time of day has the fewest delays on DEN to LGB?
The 8am–11am departure window is the strongest at 90.3% on time. The 5pm–8pm window is the weakest at 60.6%, 30 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 DEN to LGB?
June is the weakest month at 55.1% on time, compared with 86.6% in January. Across the year that is 31 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
- LGB to DEN — the return legseparate record
- Denver International (DEN) delay statistics
- DEN to PHX, a related route75.6%
- LAS to LGB, a related route76.2%
- DEN to SLC, a related route78.2%
- Southwest Airlines on-time record72.7%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
Direction matters. DEN to LGB and LGB to DEN 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.