Route profile
SLC→IAD
Flight reliability, delays and best times to fly from Salt Lake City to Washington, 1,828 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 79% of comparable major US routes (4,598 compared)
Calculated from 1,699 flights. How this is calculated
SLC → IAD arrives on time 84.9% of the time; the return trip, IAD → SLC, arrives on time 84.4% of the time.
SLC → IAD spends 22.7 minutes on the ground on a 1,828-mile trip: 16.2 minutes from pushback to wheels-up at SLC and 6.5 minutes from touchdown to gate at IAD.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
What stands out
Unlike most, it barely matters what time you fly this route, a steadier spread than 96% of 4,023 comparable routes.
89.7% on time for 9 PM–5 AM departures, against 83.3% for 3–6 PM, a narrow gap either way.
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026 · Ranked against every other route with the same kind of figure and at least 4,023 in the comparison.
When it goes wrong
July 2023 – July 2026
30 min late
against a median of 8 min early
Percentiles over 1,699 operations; cancelled and diverted flights are counted separately.
Will your connection be tight enough?
Layovers at IAD after arriving from SLC.
| Connection time | Chance of missing | Reads as |
|---|---|---|
| 30 min | 30% | Likely to miss |
| 45 min | 15% | Some risk |
| 60 min | 10% | Some risk |
| 90 min | 5.9% | Some risk |
| 120 min | 3.8% | 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 0.12% of the time, which a late arrival never shows up in.
Chance of missing is the share of 1,678 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 1,699 operations.
Any other layover length: connection checker.
Best time to fly
SLC → IAD flights departing 9 PM–5 AM arrived on time 89.7% of the time, against 83.3% for 3–6 PM departures, a gap of 6.4 percentage points.
By departure window
By departure hour
- 12 AM to 9 AM: too few flights to score
- 10 AM: 89.3% on time from 161 flights
- 11 AM to 4 PM: too few flights to score
- 5 PM: 83.3% on time from 1,055 flights
- 6 PM to 10 PM: too few flights to score
- 11 PM: 89.7% on time from 216 flights
Departure windows with fewer than 120 flights are not scored.
Why SLC → IAD runs late
July 2023 – July 2026
crew, maintenance, boarding and fueling, all within the carrier’s control
the inbound aircraft was late, so this flight started late
airspace and airport capacity, including weather-driven flow control
weather severe enough to stop this flight specifically
Share of the delay minutes US DOT attributed to each cause for SLC → IAD. 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 |
|---|---|---|---|---|---|
| Delta Air Lines | 1,127 | 83.1% | 0.89% | -8 min | 7.2% |
| United Airlines | 572 | 88.6% | 1.57% | -10 min | 3.4% |
Delta Air Lines flew 66.3% of the 1,699 flights listed.
United Airlines arrived on time 5.5 percentage points more often than Delta Air Lines 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 |
|---|---|---|---|
| DL847 Delta Air Lines | 5:55 PM | 784 | 81.4% |
Weekly and seasonal patterns
By day of week
Tuesday is historically the most reliable day and Thursday the least, a gap of 6.9 percentage points.
By month
- Jan: 86.0%
- Feb: 84.9%
- Mar: 82.5%
- Apr: 88.5%
- May: 82.9%
- Jun: 83.3%
- Jul: 71.5%
- Aug: 86.3%
- Sep: 94.1%
- Oct: 89.5%
- Nov: no data
- Dec: 82.5%
July is historically the weakest month and September the strongest, a spread of 22.6 percentage points.
Reliability over time
July 2023 – July 2026
Over the most recent 12 months (2025-08 to 2026-07), on-time arrivals averaged 86.6% against 82.6% in the 12 months before — improving by 4.0 percentage points.
Data and methodology
Calculated by FlyerIntel from 1,699 SLC → IAD 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