Route reliability record
SLC→BWI
Salt Lake City to Baltimore
- Flights
- 769
- Period
- September 2025 to August 2026
- Distance
- 1,865 mi
- Carriers
- 2
This route lands a B, 4 points better than the national rate of 77.3%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about 40 minutes on average. That rests on 769 SLC to BWI flights, with a median arrival 4 minutes early.
Best time to fly SLC to BWI: a 5am–8am departure, ideally on a Saturday. Flights in that window arrived on time 97.6% of the time and Saturday flights 88.9%, against 81.2% for the route overall.
The US average over the same twelve months is 77.3%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
81.2%
Arrivals under 15 minutes late, of 754 completed flights
Avg delay
41 min
Across delayed arrivals only, not all flights
Cancelled
1.56%
National rate is 1.89%
Best carrier
Southwest
83.6% on time across 409 flights
These figures cover 769 flights between September 2025 and August 2026. The median arrival is 4 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 BWI
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 | 409 | 83.6% | 47 min | 1.22% | B |
| Delta Air Linesthin sample | 360 | 78.3% | 35 min | 1.94% | B |
Flight by flight
Flights on SLC to BWI
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.
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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 25 points, against half a point between the best and worst carrier.
- 5am–8am42 flights97.6%
- 8am–11am28 flights—
- 11am–2pm123 flights77.5%
- 2pm–5pm65 flights73.0%
- 5pm–8pm76 flights84.7%
- 8pm–5am435 flights80.7%
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 97.6% of the time, against 73.0% for the afternoon window. That is 25 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8pm–5am window is the busiest, with 435 flights scheduled in it.
Explore
Filter SLC to BWI 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 BWI, the best departure window is 5am–8am at 97.6% on time and the worst is 2pm–5pm at 73.0%, a wide gap of 24.6 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am97.6%
- 8–11am—
- 11am–2pm77.5%
- 2–5pm73.0%
- 5–8pm84.7%
- 8pm–5am80.7%
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 34 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.
April is the best month on the calendar at 91.7% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. February was the busiest month here, with 78 flights.
Across the week, Saturday is the strongest day at 88.9% on time and Sunday the weakest at 70.9%, a spread of 18 points.
Delay causes
Why this route gets delayed
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 5,785 reported delay minutes.
- 36%Late-arriving aircraft
- 33%Carrier
- 29%National Airspace System
- 2%Extreme weather
- 0%Security
36% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 5,785 reported delay minutes here, that single category outweighs weather by 14 to one. The split is drawn from 5,785 reported delay minutes.
The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 97.6% on time here.
Cancellations sit at 1.56% against a national 1.89%, which is ordinary. Diversions add another 0.39%.
Connections and stage length
What a delay here actually costs
Badly late arrivals are rare here: only 2.9% 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.
At 1,865 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
The return leg is a different operation and performs like one: it runs 76.3% on time across 769 flights, 5 points below 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 5 points of difference.
One caution: this is a thin sample. 769 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 BWI after this flight
What to do with this
Booking this route
Put together: treat all of this as provisional. 769 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 81.2% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 754 completed flights over 12 months sit behind that.
Common questions
SLC to BWI questions
How often is SLC to BWI delayed?
About one flight in five arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 18.8% of the 769 flights in this analysis, against 22.7% nationally. Delayed flights are late by about 40 minutes on average.
How reliable is SLC to BWI compared with the rest of the country?
81.2% of flights arrive on time here against a national 77.3%, a difference of 4 points in its favour. That is worth a B on this site's grading scale.
What time of day has the fewest delays on SLC to BWI?
The 5am–8am departure window is the strongest at 97.6% on time. The 2pm–5pm window is the weakest at 73.0%, 25 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 May delays on SLC to BWI?
May is the weakest month at 58.1% on time, compared with 91.7% in April. Across the year that is 34 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
- BWI to SLC — the return legseparate record
- Salt Lake City International (SLC) delay statistics
- Baltimore/Washington International Thurgood Marshall (BWI) delay statistics
- Southwest Airlines on SLC to BWI83.6%
- Delta Air Lines on SLC to BWI78.3%
- SLC to DEN, a related route79.0%
- ATL to BWI, a related route75.2%
- SLC to PHX, a related route83.5%
- Southwest Airlines on-time record83.6%
- Delta Air Lines on-time record78.3%
- 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. SLC to BWI and BWI 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.