Carrier route record
DLORD→BOS
Delta Air Lines · Chicago to Boston
- Flights
- 981
- Period
- September 2025 to August 2026
- Share of route
- 12%
- Carriers
- 6
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with Delta Air Lines.
Delta on ORD to BOS carries a cancellation problem, not just a delay problem: 3.5% of scheduled flights never operate, against 1.9% nationally. Of the ones that do fly, about two flights in three arrive on time, worth a C− overall. The punctuality figure counts only flights that actually departed, so it flatters an operation that cancels this often. That rests on 981 flights. The strongest carrier on the route with a full sample, Envoy Air, flew 440 at 82.7% on time.
Envoy Air is the most reliable of the five carriers covered here at 82.7% on time across 440 flights.
Key figures
On time
67.4%
Arrivals under 15 minutes late, of 946 completed flights
Avg delay
90 min
Across delayed arrivals only, not all flights
Cancelled
3.47%
National rate is 1.89%
Whole route
66.6%
Every carrier on ORD to BOS, 7,864 flights
These figures cover 981 flights between September 2025 and August 2026. Beyond the headline rate, 16.6% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
Delta against every carrier on ORD to BOS
Delta flew 981 of the 7,864 flights on ORD to BOS, about 12% of it. Its 67.4% on time is about level with the route as a whole at 66.6%. Ranked by on-time rate it is number five of six carriers on the route, where the range runs from Envoy at 82.7% to American at 59.5%.
The choice of carrier is not cosmetic here. Envoy Air arrives on time 82.7% of the time; American Airlines manages 59.5%. Sample sizes sit next to every figure, because a two-point gap across 2,164 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Envoy Air | 440 | 82.7% | 67 min | 2.50% | B |
| Republic Airways | 932 | 69.7% | 79 min | 5.90% | C− |
| JetBlue Airways | 553 | 68.1% | 98 min | 3.98% | C− |
| United Airlines | 2,794 | 68.0% | 80 min | 1.79% | C |
| Delta Air Lines (this page) | 981 | 67.4% | 90 min | 3.47% | C− |
| American Airlines | 2,164 | 59.5% | 78 min | 2.91% | D |
Republic Airways cancels 5.9% 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.
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Departure window
When Delta runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 29 points, against 23 points between the best and worst carrier.
- 5am–8am225 flights82.5%
- 8am–11am292 flights74.9%
- 11am–2pm5 flights—
- 2pm–5pm231 flights54.0%
- 5pm–8pm207 flights54.6%
- 8pm–5am21 flights—
Scale runs 45% to 90%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 82.5% of the time, against 54.0% for the afternoon window. That is 29 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8am–11am window is the busiest, with 292 flights scheduled in it.
Across the year
Delta on ORD to BOS through the year
May is the best month on the calendar at 81.8% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. August was the busiest month here, with 119 flights.
Across the week, Wednesday is the strongest day at 71.5% on time and Sunday the weakest at 61.3%, a spread of 10 points.
Arrival by arrival
How late Delta on ORD to BOS runs when it is late
Delta on ORD to BOS often beats the schedule: 279 of 946 completed flights, 29%, arrived 15 minutes or more early. When Delta on ORD to BOS is late it tends to be very late: 157 of its 308 late arrivals were an hour or more behind, and 74 were two hours or more.
- 15+ min early279 flights29.5%
- Within 15 min359 flights37.9%
- 15–29 min late79 flights8.4%
- 30–59 min late72 flights7.6%
- 1–2 hours late83 flights8.8%
- 2+ hours late74 flights7.8%
Scale runs 0% to 100%.
Share of 946 completed flights by arrival against schedule.
Time lost at the gate mostly stays lost. Of 284 departures that left 15 minutes late or more, only 28 made it up before arrival. In the other direction, 52 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at BOS.
The worst days
Worst days for Delta on ORD to BOS
The latest arrival of the period was on 8 November 2025, 18 hours 3 minutes behind schedule; most of its delay minutes were filed as national airspace system delay. On three of the five worst days the largest share was filed as carrier-caused (crew, maintenance, fuelling, baggage).
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 8 November 2025 | 18 hours 3 minutes | National Airspace System |
| 25 September 2025 | 14 hours 24 minutes | Carrier |
| 4 August 2026 | 8 hours 27 minutes | Carrier |
| 20 September 2025 | 6 hours 5 minutes | Late-arriving aircraft |
| 6 November 2025 | 4 hours 44 minutes | Carrier |
Delay causes
Why Delta runs late on this route
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 28,000 reported delay minutes.
- 38%Late-arriving aircraft
- 36%National Airspace System
- 24%Carrier
- 1%Extreme weather
38% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 28,000 reported delay minutes here, that single category outweighs weather by 30 to one. The split is drawn from 27,642 reported delay minutes.
36% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 10,000 minutes out of 28,000, against a national NAS share of 21%.
Cancellations run at 3.47%, against 1.89% nationally. That is about one flight in 30 cancelled outright. A cancelled flight is invisible in every on-time figure on this page, so the punctuality numbers above describe only the flights that actually operated.
Connections and stage length
What a delay here costs
16.6% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection here, and two hours if the onward flight is on a separate ticket.
The 867 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.
The return leg is a different operation and performs like one: it runs 63.7% on time across 981 flights, 4 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 4 points of difference.
One caution: this is a thin sample. 981 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.
What to do with this
Booking Delta on ORD to BOS
Put together: the delay figures matter less here than the 3.47% cancellation rate. A late arrival costs you an hour and a half; a cancelled flight costs you the day. Book the 5am–8am departure so there is still a schedule behind you if it goes wrong, and treat a same-day connection as optimistic. 946 completed flights over 12 months sit behind that.
Related
Where to go next
- ORD to BOS, every carrier
- Delta on BOS to ORD, the return leg
- Envoy Air on ORD to BOS82.7%
- Republic Airways on ORD to BOS69.7%
- JetBlue Airways on ORD to BOS68.1%
- United Airlines on ORD to BOS68.0%
- American Airlines on ORD to BOS59.5%
- Delta Air Lines network-wide record
- Chicago O'Hare International (ORD) delay statistics
- Boston Logan International (BOS) delay statistics
- The US routes with the most cancellations
- Same route, different airline: where the carrier you pick matters most
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.