Route reliability record
MIA→BWI
Miami to Baltimore
- Flights
- 2,284
- Period
- July 2025 to June 2026
- Distance
- 946 mi
- Carriers
- 5
This route sits in the middle of the pack with a C. Close to three flights in four arrive on time by the DOT's definition, 4 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 2,284 flights, of which Southwest Airlines flew 1,180 at 75.1% on time.
The national on-time rate over the same period is 77.6%, so this route runs 4 points behind the country as a whole. Across a thousand flights that is about 40 extra late arrivals.
Key figures
On time
73.6%
Arrivals under 15 minutes late, of 2,231 completed flights
Avg delay
62 min
Across delayed arrivals only, not all flights
Cancelled
1.97%
National rate is 1.81%
Best carrier
Southwest
75.1% on time across 1,180 flights
These figures cover 2,284 flights between July 2025 and June 2026. Beyond the headline rate, 8.8% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Carrier by carrier
Which airline is most reliable on MIA to BWI
The two carriers here are closely matched: 6 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Envoy Airthin sample | 114 | 90.4% | 49 min | 0.00% | A+ |
| Southwest Airlines | 1,180 | 75.1% | 57 min | 2.03% | B |
| Frontier Airlinesthin sample | 265 | 74.2% | 90 min | 1.89% | C |
| American Airlines | 688 | 69.2% | 58 min | 2.03% | C |
| Spirit Airlinesthin sample | 37 | 52.9% | 107 min | 5.41% | F− |
No carrier stands out. Southwest tops the table at 75.1%, 6 points clear of the bottom, which is inside the range this kind of sample moves year to year.
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 38 points, against 6 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am471 flights94.5%
- 8am–11am139 flights89.1%
- 11am–2pm366 flights73.6%
- 2pm–5pm580 flights71.1%
- 5pm–8pm323 flights56.1%
- 8pm–5am405 flights61.9%
Scale runs 50% to 100%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 56.1% on time, against 94.5% for the 5am–8am 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 2pm–5pm window is the busiest, with 580 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 22 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.
July is the worst month at 61.5% on time, 22 points below January, the best at 83.8%. 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. December was the busiest month here, with 218 flights.
Across the week, Tuesday is the strongest day at 81.5% on time and Sunday the weakest at 64.5%. 17 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
One category carries most of the weight here. Late-arriving aircraft accounts for 45% of the 37,000 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 45%Late-arriving aircraft
- 30%Carrier
- 19%National Airspace System
- 5%Extreme weather
- 0%Security
45% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 37,000 reported delay minutes here, that single category outweighs weather by 9 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 36,622 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 94.5% on time here.
Cancellations sit at 1.97% against a national 1.81%, which is ordinary. Diversions add another 0.35%.
Connections and stage length
What a delay here actually costs
8.8% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route are the about an hour kind, which a normal layover absorbs.
The 946 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. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.
The return leg runs 74.7% on time across 2,286 flights, within about a point 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 2,284 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.
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. January runs 83.8% on time and July 61.5%, a swing of 22 points. If the dates move at all, move them out of July before you think about anything else. 2,231 completed flights over 12 months sit behind that.
Common questions
MIA to BWI questions
How often is MIA to BWI delayed?
About one flight in four arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 26.4% of the 2,284 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on MIA to BWI?
Southwest Airlines leads at 75.1% on time across 1,180 flights. American Airlines is at the other end on 69.2%, a gap of 6 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on MIA to BWI?
The 5am–8am departure window is the strongest at 94.5% on time. The 5pm–8pm window is the weakest at 56.1%, 38 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 July delays on MIA to BWI?
July is the weakest month at 61.5% on time, compared with 83.8% in January. Across the year that is 22 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 MIA — the return legseparate record
- Miami International (MIA) delay statistics
- Baltimore/Washington International Thurgood Marshall (BWI) delay statistics
- Envoy Air on-time record90.4%
- Southwest Airlines on-time record75.1%
- Frontier Airlines on-time record74.2%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Direction matters. MIA to BWI and BWI to MIA are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Updated monthly. How this data is collected.