Flight delayed or cancelled: checklist
What to do straight away and what to keep: the official reason, queue and call in parallel, alternatives, meals and hotel, documents and the claim afterwards.

[ ] Get the official reason and the new time
    At the desk or in the app rather than from rumours in the queue. Rights and strategy both depend on the reason.
[ ] Join the queue and call at the same time
    The airline's phone line and chat are often faster than the desk. Do both at once rather than in sequence.
[ ] Look up alternative flights yourself
    Arriving at the desk with a specific option beats waiting for an offer. Check partner airlines too.
[ ] Photograph the board, boarding pass and notifications
    With times and dates. A week later this is your only evidence of what happened and when.
[ ] Get written confirmation of the delay
    A stamp, a certificate, a message in the app. A verbal \u201cthree more hours\u201d is useless for a claim.
[ ] Ask about meals, communication and a hotel
    The entitlement often exists but is not offered. If refused, get the refusal in writing and keep your receipts.
[ ] Keep every receipt
    Food, transport, hotel, phone. Reimbursement follows documents, not your account of what you spent.
[ ] Mention your connection immediately
    Rules for a through ticket differ from separate ones. It decides who rebooks you.
[ ] Find out where your baggage is
    With a cancellation or a rebooking, baggage can travel its own route. Ask and write down the answer.
[ ] Check the consequences of buying your own ticket
    Sometimes it is reimbursed, sometimes it releases the carrier from its duties. Ask before buying, not after.
[ ] Check what your insurance covers
    Delay, cancellation, missed connection, accommodation. The policy and the carrier are separate grounds, and both can apply.
[ ] Tell the people expecting you
    A meeting, accommodation, a transfer, a car hire. Some bookings move for free if you tell them promptly.
[ ] Put the documents in one folder immediately
    Photograph the receipts the same day: in a month half will have faded and the messages will be lost.
[ ] File the claim on time and in facts
    Flight number, date, scheduled and actual times, reason, costs. A refusal is not always final — there is an appeal.

Checklist from Unload: https://unloads.me/c/flight-disruption