About 1 in 8 DL 4127 flights from Seattle arrived 15+ minutes late, diverted or cancelled over the past year (13%); 0.3% were cancelled. The typical flight landed 6 minutes early.
DL 4127: SEA → BOI
Scheduled to leave Seattle at 10:40 a.m. local time, operated by SkyWest as OO 4127. Over the past year it arrived on time 87% of the time (365 flights), in line with other DL flights on the route at that hour (88%). Last seen in the data Aug 31, 2026.
Month by month
By day of week
| Day | Flights | On time |
|---|---|---|
| Monday | 53 | 81% |
| Tuesday | 52 | 92% |
| Wednesday | 52 | 87% |
| Thursday | 52 | 85% |
| Friday | 52 | 87% |
| Saturday | 52 | 96% |
| Sunday | 52 | 83% |
Why it was late
All flights SEA → BOI · Connecting off DL 4127? Check the risk
DL 4127: BOI → SEA
Scheduled to leave Boise at 2:00 p.m. local time, operated by SkyWest as OO 4127. Over the past year it arrived on time 82% of the time (333 flights), worse than other DL flights on the route at that hour (88%). Last seen in the data Aug 31, 2026.
Month by month
By day of week
| Day | Flights | On time |
|---|---|---|
| Monday | 49 | 78% |
| Tuesday | 48 | 92% |
| Wednesday | 48 | 79% |
| Thursday | 46 | 83% |
| Friday | 47 | 77% |
| Saturday | 47 | 91% |
| Sunday | 48 | 77% |
Why it was late
All flights BOI → SEA · Connecting off DL 4127? Check the risk
Questions
How often is DL 4127 from SEA to BOI late?
Delta Air Lines 4127 from Seattle, WA to Boise, ID arrived 15 or more minutes late, was diverted or was cancelled on 13% of 365 scheduled flights between September 2025 and August 2026. 0.3% were cancelled.
How often is DL 4127 from BOI to SEA late?
Delta Air Lines 4127 from Boise, ID to Seattle, WA arrived 15 or more minutes late, was diverted or was cancelled on 18% of 333 scheduled flights between September 2025 and August 2026. 0.6% were cancelled.
Flight numbers change. Figures cover flights with this airline, number and route only. "Likely range" is the 95% interval for the true on-time rate given the number of flights. This is history, not live status: check Delta Air Lines for today's flight. Method.