Route profile
IAD→SAN
Flight reliability, delays and best times to fly from Washington to San Diego, 2,253 miles.
Right now
Aviation weather is not currently a factor.
Aviation weather is not currently a factor.
Route reliability
July 2023 – July 2026
Better than 80% of comparable major US routes (4,598 compared)
Calculated from 4,729 flights. How this is calculated
IAD → SAN arrives on time 83.2% of the time; the return trip, SAN → IAD, arrives on time 85.1% of the time.
IAD → SAN spends 28.0 minutes on the ground on a 2,253-mile trip: 22.2 minutes from pushback to wheels-up at IAD and 5.8 minutes from touchdown to gate at SAN.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
What sets this route apart
Where IAD to SAN differs most from similar routes by hour, weekday, month and airline, July 2023 – July 2026.
IAD to SAN is at its best against routes of similar length for flights scheduled at 10 AM: 95.7% arrive on time, 17 points ahead of the 78.7% those routes manage at that hour. Against all other routes the gap is 13 points.
IAD to SAN holds up on Mondays better than routes of similar length do: 85.6% on time to their 78.4%, a 7.2 points lead. Against all other routes the gap is 8.4 points.
August is kinder to IAD to SAN than to routes of similar length: 85.8% on time against 77.1%, 8.7 points better. Against all other routes the gap is 9.3 points.
United Airlines does better on IAD to SAN than on its routes of similar length: 85.4% on time here, 81.3% there, 4.1 points apart. Against all other routes the gap is 5.5 points.
IAD to SAN against comparable routes
July 2023 – July 2026| Measure | This route | Compared with | Them | Gap | Flights behind it |
|---|---|---|---|---|---|
| Hour: 10 AM departures | 95.7% | routes of similar length | 78.7% | +17.0 pts | 138 here, 58,909 there |
| Weekday: Monday | 85.6% | routes of similar length | 78.4% | +7.2 pts | 675 here, 175,321 there |
| Month: August | 85.8% | routes of similar length | 77.1% | +8.7 pts | 394 here, 104,214 there |
| Airline: United Airlines | 85.4% | routes of similar length | 81.3% | +4.1 pts | 3,559 here, 241,721 there |
Each comparison pools the flights of other routes, with this route’s own left out. Similar length means within 15% of this route’s 2,253 miles, with at least 5 such routes. A bucket is set against the most comparable group that has enough flights: similar length, then the same origin (at least 3 routes), then all other routes. Hours, weekdays and months appear only where both sides have 120 completed flights, and airlines where both have 600. The gap must be at least 2 points and 2 standard errors, and only the largest gap each way is kept per measure. These are differences in the flights counted, not causes.
Why IAD → SAN flights are cancelled
July 2023 – July 2026
IAD → SAN cancelled 53 of 4,729 scheduled flights — about 1 in every 89. The reason filed most often was the airline, 81.1% of the cancellations coded on this route — about 1 in every 110 scheduled flights.
Share of cancellations
Of 53 cancelled departures carrying a reason code.
What each reason means
Crew, maintenance, aircraft cleaning, baggage or fueling: what BTS counts as within the carrier’s own control.
43 cancellations, 81.1% of the total.
Conditions the carrier judged severe enough to stop the flight: a blizzard, a hurricane, a line of thunderstorms.
8 cancellations, 15.1% of the total.
Airport capacity, air traffic control flow programs, heavy traffic and ordinary bad weather. A system decision, not the airline’s.
2 cancellations, 3.8% of the total.
A terminal evacuation, a security breach, screening equipment failure, or screening queues over 29 minutes.
0 cancellations, 0.0% of the total.
Reason codes are the operating airline’s own filing with US DOT, not an independent finding of fault. With only one or two carriers on the route, the split mostly reflects how they file. Ordinary bad weather is filed under air traffic, so weather’s full share is larger than its bar.
53 coded cancellations were recorded on IAD → SAN; the section appears from 50.
When it goes wrong
July 2023 – July 2026
30 min late
against a median of 10 min early
Percentiles over 4,729 operations; cancelled and diverted flights are counted separately.
Will your connection be tight enough?
Layovers at SAN after arriving from IAD.
| Connection time | Chance of missing | Reads as |
|---|---|---|
| 30 min | 30% | High risk |
| 45 min | 16% | High risk |
| 60 min | 10.0% | Some risk |
| 90 min | 5.1% | Some risk |
| 120 min | 3.2% | Low risk |
This is one leg of a connection. Gate changes and the next flight's own schedule matter too. And a connection can fail before delay is even the question — this route cancels 1.12% of the time and diverts 0.51% of the time, which a late arrival never shows up in.
Chance of missing is the share of 4,652 arrivals on this route that landed later than the connection time less 30 minutes to reach the next gate.
The worst tenth of arrivals on this route land at least 30 minutes late (90th-percentile gate arrival delay), over 4,729 operations.
Any other layover length: connection checker.
Best time to fly
IAD → SAN flights departing 9 AM–12 PM arrived on time 95.1% of the time, against 69.5% for 6–9 PM departures, a gap of 25.6 percentage points.
By departure window
By departure hour
- 12 AM to 7 AM: too few flights to score
- 8 AM: 89.9% on time from 886 flights
- 9 AM: 94.9% on time from 501 flights
- 10 AM: 95.7% on time from 139 flights
- 11 AM: too few flights to score
- 12 PM: 88.2% on time from 749 flights
- 1 PM: 84.2% on time from 376 flights
- 2 PM to 3 PM: too few flights to score
- 4 PM: 78.5% on time from 210 flights
- 5 PM: 76.8% on time from 1,208 flights
- 6 PM: 70.0% on time from 580 flights
- 7 PM to 11 PM: too few flights to score
Why IAD → SAN runs late
July 2023 – July 2026
airspace and airport capacity, including weather-driven flow control
the inbound aircraft was late, so this flight started late
crew, maintenance, boarding and fueling, all within the carrier’s control
weather severe enough to stop this flight specifically
screening or terminal security incidents
Share of the delay minutes US DOT attributed to each cause for IAD → SAN. Only delays of 15 minutes or more are attributed.
Airlines on this route
Carriers with at least 200 flights, by the airline that operated each one.
| Carrier | Flights | On time | Cancelled | Median delay | Severe |
|---|---|---|---|---|---|
| United Airlines | 3,610 | 85.4% | 1.00% | -11 min | 5.1% |
| Alaska Airlines | 1,119 | 75.9% | 1.52% | -7 min | 5.9% |
United Airlines flew 76.3% of the 4,729 flights listed.
United Airlines arrived on time 9.5 percentage points more often than Alaska Airlines on this route.
Flights on this route
Flight numbers with at least 600 operations here and still on the schedule.
| Flight | Scheduled | Operations | On time |
|---|---|---|---|
| UA1930 United Airlines | 9:00 AM | 1,072 | 90.9% |
Weekly and seasonal patterns
By day of week
Tuesday is historically the most reliable day and Thursday the least, a gap of 5.9 percentage points.
By month
- Jan: 81.5%
- Feb: 81.4%
- Mar: 85.8%
- Apr: 83.6%
- May: 81.7%
- Jun: 78.0%
- Jul: 77.5%
- Aug: 85.8%
- Sep: 89.3%
- Oct: 86.5%
- Nov: 85.5%
- Dec: 83.3%
July is historically the weakest month and September the strongest, a spread of 11.8 percentage points.
Reliability over time
July 2023 – July 2026
- July 2023: 81.7% from 154 flights
- August 2023: 86.6% from 155 flights
- September 2023: 90.5% from 150 flights
- October 2023: 91.6% from 154 flights
- November 2023: 93.6% from 140 flights
- December 2023: 94.9% from 138 flights
- January 2024: 83.0% from 143 flights
- February 2024: 86.6% from 143 flights
- March 2024: 87.1% from 155 flights
- April 2024: 84.7% from 150 flights
- May 2024: 82.9% from 146 flights
- June 2024: 84.9% from 120 flights
- July 2024: 75.6% from 124 flights
- August 2024: 79.5% from 124 flights
- September 2024: too few flights to score (119)
- October 2024: 76.4% from 124 flights
- November 2024: too few flights to score (118)
- December 2024: 75.2% from 124 flights
- January 2025: 78.7% from 124 flights
- February 2025: too few flights to score (112)
- March 2025: 83.7% from 124 flights
- April 2025: 77.1% from 120 flights
- May 2025: 78.0% from 124 flights
- June 2025: 74.2% from 120 flights
- July 2025: 71.3% from 122 flights
- August 2025: 91.1% from 124 flights
- September 2025: too few flights to score (119)
- October 2025: too few flights to score (119)
- November 2025: too few flights to score (115)
- December 2025: 78.3% from 122 flights
- January 2026: too few flights to score (112)
- February 2026: too few flights to score (100)
- March 2026: too few flights to score (117)
- April 2026: too few flights to score (110)
- May 2026: 84.2% from 120 flights
- June 2026: 75.0% from 120 flights
- July 2026: 80.2% from 124 flights
Over the most recent 12 months (2025-08 to 2026-07), on-time arrivals averaged 84.4% against 77.8% in the 12 months before — improving by 6.6 percentage points.
Data and methodology
Calculated by FlyerIntel from 4,729 IAD → SAN flight records from the US DOT Bureau of Transportation Statistics, covering July 2023 – July 2026. Late means 15 or more minutes past scheduled arrival; cancelled and diverted flights are left out of on-time rates.
Full methodology · Data sources · Report a problem
Related research: How Long a Layover Needs to Be · Two Airlines on One Route · Best Time of Day to Fly From Major US Airports
Analysis last recomputed