IAH to LHR flight delays
Houston, TX (IAH) London (LHR)
798 flights · January 2025 – August 2026 · US Bureau of Transportation Statistics and UK Civil Aviation Authority
65.85%
Arrived on time
Within 15 minutes of schedule
2.76%
Cancelled
Share of scheduled flights
—
When late, late by
Average across delayed arrivals
23 min
Delay per flight
Averaged over every flight flown
What the record says about this route
Which airline you fly changes the odds here. British Airways arrived on time 10.7 points more often than United Airlines over the same period on the same route — same airports, same weather, same air traffic control. A gap that survives all of that is about how the two airlines are run.
Cancellation, not delay, is the risk worth pricing here: 2.76% of scheduled flights never operated. A late flight still gets you there. A cancelled one leaves you rebooking, and on a route with few daily departures that can mean losing a day.
The season swings this route hard. In April it ran 23.3 points more punctual than in January — a difference bigger than the one between the best and worst airlines on most routes. If the date is flexible, it is worth more than the carrier.
This route does worse than its own airport. IAH as a whole runs 12.9 points more punctual than these flights, which points at something specific to the route — the time of day it is scheduled, or the aircraft that feed it — rather than the airport.
Which airline should you fly on this route?
Over January 2025 – August 2026, British Airways arrived on time most often on IAH to LHR. United Airlines was late most often. Flights ran closest to schedule in April and worst in January.
Every airline on IAH to LHR
Ranked by how many flights each one operated. A carrier with fewer than 100 flights in the period is listed but not graded.
| Airline | Flights | On time | Cancelled | Avg delay | Grade |
|---|---|---|---|---|---|
| United Airlines | 423 | 60.87% | 2.13% | — | F |
| British Airways | 375 | 71.55% | 3.47% | — | D |
Month by month
Share of flights that arrived within 15 minutes of schedule, by month flown.
The return leg
LHR to IAH London back to Houston 74.2% on time DOther routes from Houston
Common questions
Are flights from Houston to London usually delayed?
65.85% of flights on the IAH to LHR route arrived within 15 minutes of schedule, so roughly 3 in every ten arrived late. That is worse than the average route in this record.
Which airline is most on time from Houston to London?
British Airways, at 71.55% on time across 375 flights. The least punctual on the route was United Airlines at 60.87%.
How often are IAH to LHR flights cancelled?
2.76% of scheduled flights did not operate — about 28 in every thousand. That is high enough that cancellation, not delay, is the risk worth planning around.
What is the best month to fly Houston to London?
April, when 77.1% of flights arrived on time. The worst was January at 53.8%.
What these figures do and do not tell you
Everything on this page is counted from the flights that actually operated on IAH to LHR during January 2025 – August 2026, as reported by the airlines to the US Bureau of Transportation Statistics. "On time" is the federal definition: arriving at the gate within 15 minutes of the scheduled time.
A route's record is a description of the past, not a forecast. Weather, air traffic control and the aircraft's earlier flights that day drive most delays, and none of them are predictable from a historical rate. What the record does tell you is whether this route runs late more often than others, and which carrier on it has the better history — which is the part you can actually act on when you book.
Cancellations are counted separately from delays because they are a different problem for a traveller: a late flight still gets you there. How the grade is calculated →