Baltimore, MD · departure reliability
BWI
Baltimore/Washington International Thurgood Marshall
- Departures
- 95,481
- Period
- June 2025 to May 2026
- Carriers
- 9
- US rank
- #25 by volume
Baltimore
Baltimore/Washington International Thurgood Marshall lands a B, level with the national rate of 77.4%. Roughly one flight in four arrive 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 95,481 flights, of which Delta Air Lines flew 5,322 at 84.8% on time.
Delta Air Lines is the most reliable of the nine carriers covered here at 84.8% on time across 5,322 flights.
Key figures
On time
77.3%
Departures arriving under 15 minutes late at their destination
Avg delay
65 min
Across delayed flights only
Cancelled
1.72%
National rate is 1.80%
Best carrier
Delta
84.8% on time here
These figures cover 95,000 flights between June 2025 and May 2026. The median arrival is 5 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.
Carrier by carrier
Which airlines run best out of BWI
The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 84.8% of the time; Frontier Airlines manages 67.3%. Sample sizes sit next to every figure, because a two-point gap across 3,185 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Southwest Airlines | 72,526 | 77.0% | 58 min | 1.57% | B |
| Delta Air Lines | 5,322 | 84.8% | 89 min | 1.82% | B |
| United Airlines | 4,149 | 81.4% | 79 min | 0.99% | B+ |
| Spirit Airlines | 3,671 | 76.2% | 80 min | 2.72% | B |
| American Airlines | 3,498 | 78.7% | 106 min | 2.43% | B |
| Frontier Airlines | 3,185 | 67.3% | 94 min | 3.17% | C− |
| Republic Airways | 1,338 | 81.3% | 85 min | 2.99% | B |
| Envoy Air | 1,055 | 74.4% | 80 min | 3.41% | C− |
| Alaska Airlines | 618 | 68.0% | 46 min | 0.81% | C+ |
Envoy Air cancels 3.4% of what it schedules here, the highest in the table. A cancelled flight never appears in an on-time rate, so read that column alongside the punctuality one rather than after it.
Route by route
Busiest routes out of BWI
Route-level records vary far more than the airport average. These are the 25 busiest departures from BWI, each with its own on-time rate against the airport-wide 77.3%.
| Route | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| BWI to ATL · Atlanta | 5,431 | 79.4% | 73 min | 1.99% | B |
| BWI to MCO · Orlando | 4,747 | 75.2% | 71 min | 2.23% | B |
| BWI to BOS · Boston | 3,613 | 74.2% | 69 min | 2.82% | C |
| BWI to FLL · Fort Lauderdale | 3,165 | 75.5% | 62 min | 2.31% | B |
| BWI to CLT · Charlotte | 3,043 | 79.5% | 89 min | 1.91% | B |
| BWI to DEN · Denver | 2,920 | 75.9% | 63 min | 1.16% | B |
| BWI to TPA · Tampa | 2,766 | 78.6% | 67 min | 1.92% | B |
| BWI to ORD · Chicago | 2,688 | 74.7% | 97 min | 2.31% | C |
| BWI to MIA · Miami | 2,302 | 74.0% | 74 min | 2.30% | C |
| BWI to DTW · Detroit | 2,269 | 81.3% | 79 min | 1.67% | B |
| BWI to PVD · Providence | 1,882 | 78.2% | 58 min | 1.97% | B |
| BWI to BNA · Nashville | 1,856 | 80.4% | 61 min | 1.83% | B |
| BWI to MDW · Chicago | 1,852 | 75.7% | 64 min | 2.00% | B |
| BWI to LAS · Las Vegas | 1,846 | 79.8% | 57 min | 1.14% | B |
| BWI to DAL · Dallas | 1,824 | 76.5% | 60 min | 1.86% | B |
| BWI to RDU · Raleigh | 1,814 | 80.1% | 59 min | 2.37% | B |
| BWI to BDL · Hartford | 1,763 | 81.2% | 56 min | 1.93% | B |
| BWI to LAX · Los Angeles | 1,748 | 76.1% | 58 min | 1.26% | B |
| BWI to ALB · Albany | 1,740 | 80.4% | 53 min | 1.49% | B |
| BWI to BUF · Buffalo | 1,730 | 75.4% | 53 min | 1.68% | B |
| BWI to MHT · Manchester | 1,710 | 81.7% | 58 min | 1.17% | B |
| BWI to ORF · Norfolk | 1,531 | 78.7% | 50 min | 1.37% | B |
| BWI to HOU · Houston | 1,464 | 75.9% | 54 min | 1.57% | B |
| BWI to RSW · Fort Myers | 1,452 | 75.0% | 57 min | 1.65% | B |
| BWI to JAX · Jacksonville | 1,410 | 75.6% | 57 min | 1.35% | B |
Departure window
The best time of day to leave BWI
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 26 points, against 18 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am13,429 flights90.0%
- 8am–11am21,524 flights87.9%
- 11am–2pm13,006 flights81.0%
- 2pm–5pm15,670 flights73.0%
- 5pm–8pm17,406 flights66.1%
- 8pm–5am14,446 flights64.3%
Scale runs 55% to 95%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 64.3% on time, against 90.0% 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.
Across the year
When BWI runs late
BWI's year swings by 19 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 66.2% on time, 19 points below September, the best at 85.5%. 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.
Across the week, Tuesday is the strongest day at 81.8% on time and Sunday the weakest at 71.5%. 10 points is a smaller lever than departure hour, but it is free.
Delay causes
Why BWI 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 1.38 million reported delay minutes.
- 40%Late-arriving aircraft
- 32%Carrier
- 22%National Airspace System
- 6%Extreme weather
- 1%Security
40% 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 1.38 million reported delay minutes here, that single category outweighs weather by 7 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 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 90.0% on time here.
Cancellations sit at 1.72% against a national 1.80%, which is ordinary. Diversions add another 0.18%.
7.4% of arrivals land an hour or more late, close to the national 8.2%. 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.
95,481 flights sit behind these numbers, which is a large enough sample that the headline rate is not moving on noise. Where a sub-group falls below 30 flights the site shows a dash instead of a percentage.
What to do with this
Flying out of BWI
Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 85.5% on time and July 66.2%, a swing of 19 points. If the dates move at all, move them out of July before you think about anything else.
Common questions
BWI delay questions
How often is Baltimore (BWI) delayed?
Roughly 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 22.7% of the 95,481 flights in this analysis, against 22.6% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on Baltimore (BWI)?
Delta Air Lines leads at 84.8% on time across 5,322 flights. Frontier Airlines is at the other end on 67.3%, a gap of 18 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 Baltimore (BWI)?
The 5am–8am departure window is the strongest at 90.0% on time. The 8pm–5am window is the weakest at 64.3%, 26 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 Baltimore (BWI)?
July is the weakest month at 66.2% on time, compared with 85.5% in September. Across the year that is 19 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 ATL — Atlanta79.4%
- BWI to MCO — Orlando75.2%
- Southwest Airlines on-time record77.0%
- Delta Air Lines on-time record84.8%
- United Airlines on-time record81.4%
- Spirit Airlines on-time record76.2%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
Source: US DOT Bureau of Transportation Statistics, on-time performance data, June 2025 to May 2026. Updated monthly. How this data is collected.