Flight number record
DL 1143
Delta Air Lines · Los Angeles to Houston
- Route
- LAX → IAH
- Departs
- 09:40
- Flights
- 365
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s DL 1143, check with Delta Air Lines.
DL 1143 earns an A+. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 8 points better than the national rate of 77.3%. When something does go wrong the average delay runs a little over an hour. That rests on 365 flights, with a median arrival 6 minutes early.
Set against the rest of the country, DL 1143's record is 8 points better than the US average of 77.3%. That gap is worth roughly 83 fewer late arrivals for every thousand flights.
Key figures
On time
85.6%
Arrivals under 15 minutes late, of 361 completed flights
Avg delay
70 min
Across delayed arrivals only, not all flights
Cancelled
0.55%
National rate is 1.89%
1 hour+ late
5.3%
National rate is 8.3%
These figures cover 365 flights between September 2025 and August 2026. The median arrival is 6 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.
Fare search by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
Schedule
When DL 1143 flies
DL 1143 flies LAX to IAH without a single fixed slot. Its most common scheduled departure was 09:40, used on 49 of 365 flights, with 08:55 (46 flights) and 08:45 (38 flights) next.
- Departs 09:4049 flights13.4%
- Departs 08:5546 flights12.6%
- Departs 08:4538 flights10.4%
Scale runs 0% to 100%.
Share of scheduled departures at each local time. Times used on fewer than one flight in ten are not listed.
A 09:40 departure sits in the 8am–11am window. Across every US flight scheduled in that window the on-time rate is 83.9%, and DL 1143 runs level with that at 85.6%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
Against the route
DL 1143 next to LAX to IAH
Every carrier on LAX to IAH combined arrived on time 84.6% of the time across 5,143 flights, so DL 1143 is about level with it. Delta flew 648 flights on the same city pair under all its flight numbers, including this one, and those ran 84.8% on time. Across its whole network Delta Air Lines managed 81.1%, which this flight beats by 5 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 1143 | 365 | 85.6% | 70 min | 0.55% | A+ |
| All Delta Air Lines on LAX–IAH | 648 | 84.8% | 70 min | 0.93% | B+ |
| All carriers on LAX–IAH | 5,143 | 84.6% | 61 min | 0.47% | B+ |
| Delta Air Lines, whole network | 1,039,517 | 81.1% | 71 min | 1.74% | B |
Across the year
DL 1143 quarter by quarter
DL 1143 did not run the same all year. Its best quarter was Jul–Sep 2025 at 93.3% on time and its weakest Apr–Jun 2026 at 81.1%, a swing of 12 points on roughly 73 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.
- Jul–Sep 202530 flights93.3%
- Oct–Dec 202592 flights88.0%
- Jan–Mar 202690 flights87.4%
- Apr–Jun 202691 flights81.1%
- Jul–Sep 202662 flights82.3%
Scale runs 75% to 100%.
By weekday, DL 1143 did best on Monday at 94.3% on time and worst on Saturday at 75.0%. Each day rests on about 52 flights, so a gap of 19 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late DL 1143 runs when it is late
DL 1143 often beats the schedule: 100 of 361 completed flights, 28%, arrived 15 minutes or more early. The 52 late arrivals split 17 under half an hour, 16 between 30 and 60 minutes, and 19 an hour or more.
- 15+ min early100 flights27.7%
- Within 15 min209 flights57.9%
- 15–29 min late17 flights4.7%
- 30–59 min late16 flights4.4%
- 1–2 hours late12 flights3.3%
- 2+ hours late7 flights1.9%
Scale runs 0% to 100%.
Share of 361 completed flights by arrival against schedule.
5 of 40 late departures made up the time and arrived on time, 13% of them. 17 flights left on time and still arrived late.
The worst days
Worst days for DL 1143
The latest arrival of the period was on 23 December 2025, 6 hours 55 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on three of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 23 December 2025 | 6 hours 55 minutes | Carrier |
| 1 April 2026 | 6 hours 42 minutes | Carrier |
| 18 September 2025 | 5 hours 4 minutes | Carrier |
| 22 May 2026 | 4 hours 5 minutes | Late-arriving aircraft |
| 7 November 2025 | 2 hours 24 minutes | National Airspace System |
Delay causes
Why DL 1143 runs late
Carrier accounts for 52% of the 3,661 delay minutes carriers reported here, and the remaining four split what is left.
- 52%Carrier
- 25%National Airspace System
- 23%Late-arriving aircraft
The largest share of delay minutes, 52%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 1,903 of the 3,661 delay minutes reported here. The split is drawn from 3,661 delay minutes reported on DL 1143.
Cancellations are rare at 0.55%, below the national 1.89% 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 routes
What a delay on this flight costs
5.3% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last a little over an hour, which a normal layover absorbs.
The 1,379 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 same number turns up on one other city pair in the data, including IAH to LAX (104), but none flew often enough under DL 1143 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to LAX to IAH only.
One caution: this is a thin sample. 365 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 DL 1143
For a booking, DL 1143 has one of the better records a US domestic flight can show: 85.6% on time and 0.55% cancelled. That is a base rate, not a promise about any single day.
Related
Where to go next
- LAX to IAH, every carrier and departure
- IAH to LAX, the return direction
- United Airlines 2377 on the same route85.9%
- United Airlines 1416 on the same route91.8%
- Frontier Airlines 1756 on the same route70.2%
- United Airlines 491 on the same route90.5%
- Delta Air Lines 1287 on the same route83.9%
- United Airlines 2086 on the same route85.8%
- Los Angeles International (LAX) delay statistics
- George Bush Intercontinental (IAH) delay statistics
- Delta Air Lines on-time record
- Every Delta Air Lines flight number with a record
- The most and least reliable flight numbers in the US
- Worst months to fly in the US, ranked by the data
A flight number here means Delta Air Lines’s own number as it reports to the DOT. How the figures are computed is on the methodology page.
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.