RouteRankingWe tracked every Heathrow flight from Cork, Dublin, Shannon and Knock over the past 60 days and the gap between the best and worst performers is striking.
The short answer: Shannon and Cork are the standout performers based on our dataset. Dublin offers the higher number of flight options, but has the most variance in terms of reliability. Knock has just one Heathrow service and it sits in the middle of the pack at a very respectable ~90% on-time arrival rate.
See the full rankings on the RouteRanking leaderboard.
So, what counts as on time?
OAG, the global aviation data authority, defines an on-time arrival as one that touches down within 15 minutes of the scheduled arrival time. That is the same standard used by airlines, airports and regulators worldwide. We have applied this logic to our dataset in this analysis.
OAG's annual Punctuality League benchmarks consistently show that top-performing airports achieve on-time rates above 85%. Anything below 80% is considered poor performance by industry standards. Keep those numbers in mind as you read through the results below. The Irish airports are performing strongly on the Heathrow route versus OAG's industry standards.
Cork to Heathrow Flights
Cork offers frequent Aer Lingus to Heathrow services daily. All bar one clear the 85% industry benchmark comfortably, and two of them are among the best-performing Heathrow flights from any Irish airport.
| Route | Flight | Departure | On-Time % |
|---|---|---|---|
| Cork to London Heathrow | EI722 | 17:35 | 97.4% |
| Cork to London Heathrow | EI718 | 16:05 | 97.3% |
| Cork to London Heathrow | EI724 | 20:30 | 96.7% |
| Cork to London Heathrow | EI714 | 11:55 | 86.4% |
| Cork to London Heathrow | EI710 | 07:40 | 84.1% |
The afternoon and evening departures are exceptionally consistent, all arriving on time more than 96% of the time. The morning flight, EI710 at 07:40, drops to 84.1% which is still above the industry average but a notable gap compared to the others.
The counterintuitive finding here is that the later you fly from Cork to Heathrow, the more likely you are to arrive on time. EI722 at 17:35 outperforms the early morning departure by more than 13 percentage points.
See the full breakdown here: www.routeranking.com/results/ork-lhr.
Dublin to Heathrow
Dublin has the most Heathrow flights of any Irish airport, with nine Aer Lingus services tracked. That choice comes with a wider spread in reliability.
| Route | Flight | Departure | On-Time % |
|---|---|---|---|
| Dublin to London Heathrow | EI164 | 12:05 | 98.4% |
| Dublin to London Heathrow | EI184 | 19:45 | 98.2% |
| Dublin to London Heathrow | EI172 | 15:30 | 96.8% |
| Dublin to London Heathrow | EI158 | 10:00 | 96.7% |
| Dublin to London Heathrow | EI156 | 08:45 | 91.9% |
| Dublin to London Heathrow | EI178 | 18:30 | 90.0% |
| Dublin to London Heathrow | EI168 | 14:15 | 82.0% |
| Dublin to London Heathrow | EI152 | 06:40 | 80.0% |
| Dublin to London Heathrow | EI154 | 07:35 | 75.4% |
The top of the table is excellent. EI164 at 12:05 and EI184 at 19:45 both sit above 98%, which is outstanding performance by any standard.
The bottom of the table tells a different story. EI154 at 07:35 arrives on time just 75.4% of the time, the lowest of any flight tracked in this dataset, based on the past 60 days of data. EI152 at 06:40 will arrive as scheduled 80% of the time, which is respectable. When EI154 is delayed, the average overrun is significant, the worst recorded delay in our dataset was 119 minutes.
The pattern from Dublin mirrors what we saw from Cork: early morning flights have a lower reliability rating than their afternoon or evening counterparts. The two worst flights both depart before 08:00. If you are flying from Dublin to Heathrow and have early meetings or somewhere to be, build in some buffer to keep your stress levels low.
See the full breakdown here: www.routeranking.com/results/dub-lhr.
Shannon to Heathrow
Shannon operates three Aer Lingus Heathrow services. The results are impressive, particularly for the afternoon and evening options.
| Route | Flight | Departure | On-Time % |
|---|---|---|---|
| Shannon to London Heathrow | EI386 | 17:30 | 96.8% |
| Shannon to London Heathrow | EI388 | 20:05 | 96.3% |
| Shannon to London Heathrow | EI380 | 07:50 | 77.4% |
The evening departures from Shannon are among the most reliable Heathrow services from any Irish airport. EI386 at 17:30 arrives on time 96.8% of the time and EI388 at 20:05 is close behind at 96.3%.
The morning flight is a different matter. EI380 at 07:50 arrives on time 77.4% of the time, which sits below OAG's 80% threshold. If you are travelling from the west of Ireland and need certainty, the afternoon departure is the clear choice.
See the full breakdown here: www.routeranking.com/results/snn-lhr.
Knock to Heathrow
Ireland West Airport Knock operates a single Heathrow service, EI916, which departs at 13:00. With 59 flights in the sample, the data is solid.
| Route | Flight | Departure | On-Time % |
|---|---|---|---|
| Knock to London Heathrow | EI916 | 13:00 | 89.8% |
89.8% clears the 85% industry benchmark and puts Knock's only Heathrow service comfortably in the reliable category. This is an impressive reliability performance, worth pointing out that Knock has the benefit of flying to Heathrow once the morning rush has finished.
See the full breakdown here: www.routeranking.com/results/noc-lhr.
How the airports compare
Looking at Heathrow performance alone, here is how each Irish airport stacks up based on the average on-time percentage across all tracked flights.
| Route | Airport | Best flight | Best on-time % | Worst flight | Worst on-time % |
|---|---|---|---|---|---|
| Cork to London Heathrow | Cork | EI722 17:35 | 97.4% | EI710 07:40 | 84.1% |
| Dublin to London Heathrow | Dublin | EI164 12:05 | 98.4% | EI154 07:35 | 75.4% |
| Shannon to London Heathrow | Shannon | EI386 17:30 | 96.8% | EI380 07:50 | 77.4% |
| Knock to London Heathrow | Knock | EI916 13:00 | 89.8% | EI916 13:00 | 89.8% |
Cork is the standout airport for consistency. All three of its Heathrow flights clear 84% and two exceed 97%.
Dublin offers the highest peak performance with EI164 clocking in at 98.4%, the single most reliable Heathrow flight from any Irish airport. EI154 at 75.4% is the worst-performing flight in this comparison by a significant margin.
Shannon mirrors the Cork pattern closely: strong afternoon and evening performance, a weaker morning service. The gap between its best and worst is wider than Cork's.
The time of day trend is consistent across every airport in this dataset. Morning departures, particularly those before 08:00, perform worse than afternoon and evening departures. This holds whether you are flying from Cork, Dublin or Shannon. The only exception is Knock, which has no early morning Heathrow service.
For the full picture across all UK routes from Irish airports, see the RouteRanking Leaderboard
Frequently Asked Questions
Which Irish airport has the most reliable flights to Heathrow? Cork is the most consistently reliable, with all three Heathrow services above 84% and two above 97%. Dublin has the best single flight but also the worst.
What does on time mean for flights? OAG, the global aviation data authority, defines an on-time arrival as landing within 15 minutes of the scheduled arrival time. That is the standard used throughout this analysis.
Is the morning flight to Heathrow more likely to be delayed? Based on 60 days of data, yes. Early morning Heathrow departures from Dublin, Cork and Shannon all underperform compared to afternoon and evening services on the same routes. The pattern is consistent across all three airports.
Which airlines fly from Irish airports to Heathrow? All Heathrow services from Cork, Dublin, Shannon and Knock are operated by Aer Lingus.
How often are Heathrow flights delayed from Ireland? It varies significantly by flight. The best performers arrive on time more than 97% of the time. The worst in this dataset, EI154 from Dublin at 07:35, arrives on time 75% of the time.
Where can I see the latest data? All figures are updated daily on RouteRanking. See the Cork to Heathrow, Dublin to Heathrow, Shannon to Heathrow and Knock to Heathrow route pages, or view all Irish routes on the leaderboard.