Route reliability record
PWM→BWI
Portland to Baltimore
- Flights
- 1,341
- Period
- July 2025 to June 2026
- Distance
- 452 mi
- Carriers
- 1
This route lands a B+, 4 points better than the national rate of 77.6%. Roughly one flight in five arrives 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 1,341 PWM to BWI flights, with a median arrival 2 minutes early.
Best time to fly PWM to BWI: a 8am–11am departure, ideally on a Wednesday. Flights in that window arrived on time 91.7% of the time and Wednesday flights 87.8%, against 81.8% for the route overall.
Set against the rest of the country, this route's record is 4 points better than the US average of 77.6%. That gap is worth roughly 42 fewer late arrivals for every thousand flights.
Key figures
On time
81.8%
Arrivals under 15 minutes late, of 1,325 completed flights
Avg delay
58 min
Across delayed arrivals only, not all flights
Cancelled
0.89%
National rate is 1.81%
Best carrier
Southwest
81.8% on time across 1,341 flights
These figures cover 1,341 flights between July 2025 and June 2026. The median arrival is 2 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 airline is most reliable on PWM 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 | 1,341 | 81.8% | 58 min | 0.89% | B+ |
Best ways to make this trip
The most reliable ways to fly Portland to Baltimore
Every airline on this route and on the routes between nearby airports, ranked by how often a scheduled flight actually operated and arrived on time. 2 of the top 3 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. PWM → BWIPortland to Baltimore | Southwest Airlines | 81.1% | 81.8% | 0.89% | 8am–11am, Wed | — |
| 2. PWM → DCAPortland to Washington | American Airlines | 74.4% | 76.1% | 2.29% | 5am–8am, Sat | — |
| 3. PWM → DCAPortland to Washington | PSA Airlines | 66.0% | 70.1% | 5.84% | 5am–8am, Sun | — |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
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 28 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am372 flights89.4%
- 8am–11am120 flights91.7%
- 11am–2pm328 flights82.0%
- 2pm–5pm352 flights78.9%
- 5pm–8pm169 flights63.7%
- 8pm–5am—
Scale runs 55% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 63.7% on time, against 91.7% for the 8am–11am 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 5am–8am window is the busiest, with 372 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 25 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 65.5% on time, 25 points below September, the best at 90.9%. 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. August was the busiest month here, with 135 flights.
Across the week, Wednesday is the strongest day at 87.8% on time and Tuesday the weakest at 79.9%. 8 points is a smaller lever than departure hour, but it is free.
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 14,000 reported delay minutes.
- 35%Late-arriving aircraft
- 34%Carrier
- 25%National Airspace System
- 6%Extreme weather
- 1%Security
35% 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 14,000 reported delay minutes here, that single category outweighs weather by 6 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 13,868 reported delay minutes.
The practical consequence: the 8am–11am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 91.7% on time here.
Cancellations are rare at 0.89%, below the national 1.81% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.
Connections and stage length
What a delay here actually costs
Badly late arrivals are rare here: only 4.1% land an hour or more behind schedule, against 8.1% 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 452 miles this is a short hop, and stage length matters more than it looks. A flight this short spends under two hours in the air, which leaves almost nothing to claw back a late pushback with. Delay here is decided on the ground, in the turn, which is why the 8am–11am window matters as much as it does.
The return leg runs 79.2% on time across 1,341 flights, within 3 points 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 1,341 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.
Work out the risk of missing a connection in BWI after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 90.9% on time and July 65.5%, a swing of 25 points. If the dates move at all, move them out of July before you think about anything else. 1,325 completed flights over 12 months sit behind that.
Common questions
PWM to BWI questions
How often is PWM to BWI delayed?
Roughly 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 18.2% of the 1,341 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
How reliable is PWM to BWI compared with the rest of the country?
81.8% of flights arrive on time here against a national 77.6%, 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 PWM to BWI?
The 8am–11am departure window is the strongest at 91.7% on time. The 5pm–8pm window is the weakest at 63.7%, 28 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 PWM to BWI?
July is the weakest month at 65.5% on time, compared with 90.9% in September. Across the year that is 25 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 PWM — the return legseparate record
- Baltimore/Washington International Thurgood Marshall (BWI) delay statistics
- PWM to ORD, a related route77.2%
- ATL to BWI, a related route75.6%
- PWM to DCA, a related route74.5%
- Southwest Airlines on-time record81.8%
- 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. PWM to BWI and BWI to PWM 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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.