My United flight from DUB to IAD was delayed by more than 3 hours due to late arrival of inbound aircraft due to maintenance. EU regulations entitle me to compensation of 600 Euros. I logged into my United account and sent them the following: "My flight UA127 on 3 May 2018 from Dublin to Washington Dulles was delayed by 3 hours 23 minutes due to a mechanical issue with inbound plane (UA152 ORD->DUB). I am writing to find out if I am entitled to compensation under REGULATION (EC) No 261/2004 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL. My understanding of this European law is that it entitles passengers to compensation when flights leaving from Europe are delayed. This flight was delayed for over three hours. Thank you for letting me know if this is something I am entitled to. As always, I appreciate all of the excellent service I receive on United. Attached are screenshots of the inbound plane delay due to mechanical issues and my flight delay as captured from the United App." In 24 hours I got the following reply: "On behalf of United Airlines, I want to apologize for the inconvenience you experienced as a result of the delay of UA 127 from Dublin to Washington Dulles on May 3, 2018. We truly appreciate your understanding that the safety of our customers and crew members is our number one priority. We will not operate any aircraft until our stringent operational standards are met. Please accept my apology for the disruption in your travel plans. We appreciate your patience while we reviewed the circumstances surrounding the disruption in your travel plans. United Airlines has determined that, in this case, monetary compensation under European Union Regulation EC261/2004 is applicable. Monetary compensation will be awarded only to customers who were holding a confirmed reservation, a fare paid ticket, and were checked in and available to board the aircraft in accordance with United’s Contract of Carriage. As alternative options to your claim for compensation under European Union EC261/2004 regulation, we would like to offer you a choice of a $900 (USD) United Travel Certificate* (redeemable and transferable toward the purchase of any United or United Express operated flight) or 27,500 United MileagePlus® miles (redeemable on flights operated by United, United Express or by Air Canada, ANA, Austrian, Lufthansa, SAS Scandinavian, Swiss, Thai and 20 additional Star Alliance partners worldwide.) Travel Certificates are valid for twelve (12) months and MileagePlus® miles are valid for 18 months. If you are not already a MileagePlus® member, simply enroll online at: http://www.united.com/mileageplus, then respond with your new account number and we’ll credit your account. If you desire one of these options, please let us know your preference and we’ll facilitate delivery via e-mail within 3-5 business days. However, if you still wish to pursue cash compensation under EU regulation in the amount of €600, please provide a valid address where you would like for us to send it. You will receive your compensation in the form of a USD check in your local currency. Processing of your payment may take up to 6 weeks." I decided to take the $900 travel voucher which will pay for most of my next flight to Europe in Sept.