Transatlantic route record · UK CAA departure punctuality
LHR→IAH
London to Houston
- Flights
- 2,689 both ways
- Carriers
- 2
- Distance
- 4,823 mi
- Period
- September 2025 to August 2026
Over the twelve months to August 2026, 72.5% of departures from London Heathrow to George Bush Intercontinental left within 15 minutes of their planned time, from 1,346 flights the UK Civil Aviation Authority matched to a schedule. That is 4 points behind the 76.4% recorded across every UK departure to the United States, and it ranks 39th of the 50 UK-to-US routes with a usable record. Roughly one flight in four left at least 15 minutes behind schedule, and 21 of 1,367 scheduled departures, 1.5%, did not operate at all.
The route's 72.5% is an improvement of about a point on the same months a year earlier, when 71.5% left on time. Across every departure from the 25 UK airports the CAA reports, to any destination, 72.4% left within 15 minutes in the same period; transatlantic departures run slightly better than the UK average, partly because wide-body long-haul flights are scheduled with more slack than short-haul rotations. Within the route, the spread between carriers is 11 points, which matters more to a booking than the route average does.
Key figures
Left on time
72.5%
Within 15 minutes of schedule, of 1,346 departures (CAA)
Avg delay
16 min
Across all departures, early counted as zero
Cancelled
1.54%
All UK-to-US departures: 2.16%
3+ hours late
0.87%
The UK261 compensation threshold
5.6% of departures left more than an hour late, and 0.87% left three hours or more behind schedule, roughly one flight in 100. Three hours at arrival is the threshold at which UK261 compensation becomes payable, £520 a passenger on a sector of this length; the CAA measures the departure, so a flight in that band left the gate three hours late, which is not quite the same test but rarely ends differently after seven hours over the Atlantic. The average delay across every matched departure, early ones counted as zero, was 15.9 minutes, against 14.2 for all UK-to-US departures.
Carrier by carrier
Which airline leaves LHR for IAH on time
United Airlines is the most punctual carrier on the departing leg at 77.7% across 724 flights, and British Airways the least at 66.6% across 622. 11 points between them is a large gap for one city pair, large enough to prefer the better carrier at a modest fare difference. No carrier here cancels unusually often; the highest cancellation rate on the route is British Airways's 2.4%.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 730 | 77.7% | 13 min | 0.82% | B+ |
| British Airways | 637 | 66.6% | 19 min | 2.35% | C |
Flights are scheduled departures in the CAA file, operated plus cancelled; on time is within 15 minutes of the planned off-block time. The DOT count below includes the return direction and may differ.
How late is late
How delays on LHR to IAH are distributed
- Early15+ min early0.2%
- On timeup to 15 min late72.3%
- 16–30 min11.1%
- 31–60 min9.3%
- 1–2 hours3.7%
- 2–3 hours1.0%
- 3–6 hourscompensation threshold0.8%
- Over 6 hours0.1%
Scale runs 0% to 100%.
Across the year
When LHR to IAH runs late
November was the weakest month for departures at 64.9% on time and April the strongest at 86.9%, a swing of 22 points across the year. That is a wide seasonal range, wider than the gap between the best and worst carriers, so the month you fly matters more than the airline you pick. The DOT's count puts the busiest month at 245 flights in May 2026 and the thinnest at 191 in February 2026, so capacity follows the summer peak.
Flights per month, both directions
- July 2025244
- August 2025223
- September 2025230
- October 2025237
- November 2025213
- December 2025218
- January 2026210
- February 2026191
- March 2026216
- April 2026223
- May 2026245
- June 2026239
The DOT's international report counts flights in both directions together: 2,689 between LHR and IAH from July 2025 to June 2026, about four departures a day in each direction, carrying 512,034 passengers. That makes it the 11th busiest of 31 US routes from London Heathrow and the busiest of 5 European routes into IAH.
The return leg
IAH to LHR: arrivals back into London
Coming the other way, 70.3% of arrivals from George Bush Intercontinental into London Heathrow reached the gate within 15 minutes of schedule, across 1,346 flights. 16% arrived more than 15 minutes early, which is normal for an eastbound crossing with the jet stream behind it and a schedule padded for the days it is not. 1.17% of those arrivals were three hours or more late, the figure that decides a compensation claim on the return trip, and 1.5% were cancelled.
Arrived on time
70.3%
Within 15 minutes, of 1,346 arrivals
Early
16.0%
More than 15 minutes ahead of schedule
Cancelled
1.46%
3+ hours late
1.17%
Arrival delay, the compensation test
- Early15+ min early16.0%
- On timeup to 15 min late54.3%
- 16–30 min12.2%
- 31–60 min8.9%
- 1–2 hours4.9%
- 2–3 hours1.2%
- 3–6 hourscompensation threshold1.0%
- Over 6 hours0.1%
Scale runs 0% to 100%.
The departure airport
How London Heathrow is running
EUROCONTROL's figures for London Heathrow as a whole, every airline and every destination: 80.3% of departures and 80.5% of arrivals within 15 minutes of schedule from 1 January to 21 October 2026, with 96.7% of scheduled flights operated. The last seven days ran at 80.8% for departures, in line with the year. Air traffic flow management delay attributed to the airport averaged 1.2 minutes per arriving flight this year, 1.0 over the last week.
| Window | Departures on time | Arrivals on time | Schedules operated | ATFM delay / arrival |
|---|---|---|---|---|
| Yesterday (21 October 2026) | 77.2% | 80.6% | 98.2% | 2.8 min |
| Last 7 days | 80.8% | 84.1% | 98.1% | 1.0 min |
| Year to date | 80.3% | 80.5% | 96.7% | 1.2 min |
Every US route from London Heathrow, and its full punctuality record
The arrival airport
Landing at George Bush Intercontinental
George Bush Intercontinental is scored on this site from the DOT's domestic data: 79.1% of its 118,936 domestic departures arrived on time over the last twelve months, with delayed flights running a little over an hour late, and 1.10% were cancelled. Those are domestic flights, not this route, but an arriving transatlantic flight shares the same runways, the same weather and the same ground delay programmes, so a bad day at IAH reaches a flight from LHR just as surely. The airport's own page has the hour-by-hour and month-by-month detail, and its live FAA status appears above when the FAA has something to say.
Domestic on time
79.1%
Arrivals under 15 minutes late (DOT)
Avg delay
75 min
Delayed domestic flights only
Cancelled
1.10%
Domestic departures
118,936
Last twelve months
George Bush Intercontinental (IAH) delay statistics, hour by hour and month by month
Your rights
UK261 on LHR to IAH
Every flight that departs London Heathrow falls under UK261, the retained version of the EU regulation, whichever airline flies it and wherever it lands. If it arrives at George Bush Intercontinental three hours or more late, or is cancelled with under 14 days' notice, and the cause was within the airline's control, each passenger is owed £520 (£260 if the airline got you there under four hours late), on top of rebooking and care. Weather, air traffic control restrictions and strikes outside the airline are the usual exemptions. The return flight from IAH is covered only when the carrier is UK or EU based. The sector is about 4,823 miles, 7,760 km, which puts it in the top distance band.
Delayed three hours or more? Check a claim with Compensair →
What to do with this
Booking LHR to IAH
Booked blind, LHR to IAH is a C route by the departure record. Booked with the numbers, it is United Airlines at 77.7%, outside November if the dates are flexible, and a connection at IAH with at least two hours in hand, because 6% of departures were an hour or more late and immigration comes before any onward flight.
Common questions
LHR to IAH questions
How often are LHR to IAH flights delayed?
Roughly one flight in four leaves London Heathrow at least 15 minutes behind schedule, 27.5% of the 1,346 departures the CAA matched between September 2025 and August 2026. 5.6% left more than an hour late and 0.87% three hours or more. A further 1.5% of scheduled departures were cancelled.
Which airline is most punctual from LHR to IAH?
United Airlines, at 77.7% of departures within 15 minutes across 724 flights. British Airways is lowest at 66.6%. British Airways also cancelled more often, 2.4% against 0.8%.
Can I claim compensation for a delayed LHR to IAH flight?
Yes, if the flight arrived three hours or more late or was cancelled at short notice for a reason within the airline's control: departures from London Heathrow are covered by UK261 whichever airline operates them. The fixed amount for a sector of this length is £520 a passenger, £260 if the airline got you there under four hours late. On this route 0.87% of departures left three hours or more late over the last twelve months. The return from IAH is covered only on a UK or EU carrier.
What is the worst month for delays on LHR to IAH?
November, at 64.9% of departures on time, against 86.9% in April, the best month. A gap that size is worth moving flexible dates for.
Related
Where to go next
- London Heathrow (LHR): every US route
- George Bush Intercontinental (IAH) delay statistics
- LHR to JFK, New York (JFK)14,572 flights
- LHR to EWR, Newark (EWR)6,322 flights
- LHR to LAX, Los Angeles (LAX)5,981 flights
- LHR to ORD, Chicago (ORD)5,762 flights
- FRA to IAH, from Frankfurt1,394 flights
- AMS to IAH, from Amsterdam1,383 flights
- CDG to IAH, from Paris702 flights
- MUC to IAH, from Munich576 flights
- Every Europe-to-US route and airport
The departure record is the CAA's, measured at London Heathrow; the arrival record for the return leg is also measured at London Heathrow. Nothing here is measured at IAH, where the DOT keeps no record of international flights.
Sources: US DOT Bureau of Transportation Statistics, International Report (flights and passengers by carrier and airport pair), July 2025 to June 2026; UK Civil Aviation Authority punctuality statistics, September 2025 to August 2026; EUROCONTROL Aviation Intelligence Portal, airport punctuality and ATFM delay to 21 October 2026. Rebuilt 22 October 2026; the EUROCONTROL figures refresh with each weekly build, the others when their publisher releases a month. How these sources differ.