Aer Lingus possible flight problems

I don't think you will have much choice if they put you on a US airline - you can probably ask but Aer Lingus but it will mainly be upto them as to how they route you to your destination. Flying out of Denver, your choices will be limited: the daily BA flight to LHR, the 3 or so times a week AF flight to Paris, the flight to Iceland (3 times a week?) or the newly started Turkish air flight but that will take you a long way around to get to Dublin (this too is 3 or 4 times a week). Else, you have the daily UA notstops to LHR (2), MUC, FRA and the LH nonstops to MUC & FRA. It will all come down to where there are open seats and how quickly they can get you to DUB should the pilots issue come to pass.

Regarding the return flight. My understanding is that all flights originating in the EU are subject to EU 261 rules. So even a US airline would need to pay compensation when warranted.

"Regarding the return flight. My understanding is that all flights originating in the EU are subject to EU 261 rules. So even a US airline would need to pay compensation when warranted."

I looked at that specifically, and no, only EU carriers are held to the EU 261.

I'm curious- Dublin is in an EU country but London is not, since Brexit. Does that make a difference?

"I'm curious- Dublin is in an EU country but London is not, since Brexit. Does that make a difference?"

Even though the UK left the European Union, the UK has its own national law that mirrors EU 261, called UK261.

Regarding the return flight. My understanding is that all flights
originating in the EU are subject to EU 261 rules. So even a US
airline would need to pay compensation when warranted.

That is correct.

"Regarding the return flight. My understanding is that all flights
originating in the EU are subject to EU 261 rules. So even a US
airline would need to pay compensation when warranted.

That is correct."

That is good to know. So a direct AA flight to London has a problem. Not covered. But the return AA leg from London to the USA is covered by EU 261? I have never looked at a US carriers website for any links to EU 261 compensation. I wonder if they actually have it or they are just going make you work for it. Let's hope I never have to deal with any of this.

London is not in the EU, so none of the flights mentioned are covered. But to qoute Wikipedia:

The regulation applies to any passenger:

• departing from an airport located in the territory of a Member State to which the Treaty applies;
• departing from an EU/EEA member state, or
• travelling to an EU/EEA member state on an airline based in an EU/EEA member state

The flight from London back to the US would not be covered under EU 261 because the UK is no longer in the EU. But, they have their own law that is similar.

If your return flight from Dublin is delayed or cancelled at the last minute, , regardless of the airline, it is covered under EU 261.

In 2018, my United Airlines flight from Milan to Newark, NJ was 3 hours late for takeoff. I requested the EU 261 compensation from United’s Customer Service and got the appropriate compensation with a check in less than 30 days. So at least at that time it was an US airline flight that originated in the EU and was eligible for compensation.