Tens of thousands of airline travellers have seen their holidays affected by clouds of volcanic ash from Iceland.
A new policy, allowing flights through areas of low-density ash, has now been adopted by aviation authorities across Europe.
However, there is the chance of further disruption during the summer depending on activity from the volcano.
In the meantime, some travellers who were delayed, in the UK and elsewhere, may feel aggrieved they did not receive the help they expected from their airline, travel insurer or tour operator.
I was stranded and my airline did not give me enough help, for instance finding a hotel or food.
If you think the airline did not meet its obligations, complain to it first.
If you get nowhere, your next port of call is the Air Transport Users Council (ATUC) , the official airline watchdog in the UK.
"My worry is, the airlines may dig their heels in," said an ATUC spokesman.
It offers a mediation process to help disgruntled passengers, but it does not have any statutory powers to force airlines to obey its will.
It will need to see the airline's response to your complaint and will then evaluate if you have a real grievance or not.
If it thinks you do, ATUC will take it up with the airline, probably higher up the managerial food chain.
You will then be advised if your complaint has been successful or not.
If not, ATUC will offer further advice and if you want, you can lodge a claim in your local County Court for any losses you still think you have suffered.
My travel insurer says my policy did not cover me.
Your insurer may be right, as there is no such thing as a standard travel insurance policy, so you need to read your policy carefully.
It may simply not have included any cover for extreme weather events, or natural disasters, which are beyond anyone's control.
Generally, those who never made it out on a holiday will get their money back, but those who incurred costs trying to get home might not.
If, however, you think the insurer is trying to dodge its genuine obligations, you should make a direct complaint.
The insurer will have a formal complaints procedure, and the Association of British Insurers (ABI) says that should be used, and exhausted, first.
After that, you will have the right to take your complaint to the Financial Ombudsman Service (FOS) , which can enforce a judgement in your favour.
Who gets priority on seats now flights are running again?
Passengers who have always been booked on a specific flight get priority.
Any spare seats generally go to "unaccompanied minors" first. Their ticket usually has a premium as the airline has to look after them.
After that, it is up to the airline who gets brought back first.
Remember that in the meantime, those flying with European carriers into or out of the EU, or non-EU carriers leaving the EU, have the right to a refund or being re-routed.
If they chose the latter, they have the right to care - such as accommodation and meals - while they wait.
My whole package holiday went down the drain.
Tour operators who are members of the Association of British Travel Agents (ABTA) should help you, which means looking after you if you were stuck abroad.
If you never left, they should give you another holiday or offer you your money back.
If you have a complaint, write to the company, and if still dissatisfied, complain to them again.
If that gets you nowhere, write with your complaint to ABTA, which offers an arbitration process.
"We will contact the trader, mediate on your dispute and try to reach an amicable settlement," said a spokesman.
If you sign up for this, though, you will have to accept that the outcome is legally binding.
If you do not like that idea, then the alternative is to go to your County Court instead to sue for any losses.
What are the best sources of advice?
Apart from the organisations mentioned above, you could look at the website of the consumers' organisation Which? or contact the UK European Consumer Centre (UKECC) .
It is associated with the Trading Standards Institute and is funded by the European Commission.
It specialises in giving advice and guidance on the rules and regulations that apply to cross border shoppers in the EU - and that includes travellers.
In this case, it says it is concentrating on UK residents who had flown with an overseas airline, or overseas residents who had flown with a UK airline.
"We are starting to get queries coming in," said a spokeswoman.
So far, people have been asking what their rights are, if there is additional compensation for hotel and car hire costs, and for people stuck overseas, how to deal with being stranded in a foreign country.
Will I get paid for the work days I missed?
Missing work because you were stranded overseas is considered to be unauthorised leave and your employer does not have to pay you.
Many employers would suggest that the time is taken as holiday but the employee would have to agree to this.
James Wilders, an employment partner at the law firm Dickinson Dees, said employers must meet any additional expenses incurred by staff while abroad on business, such as accommodation and subsistence costs as well as reasonable travel arrangements.
However, knock-on costs such as childcare or missed events would usually not be covered.
I parked my car at the airport, do I have to pay the extra cost?
Drivers could end up with hefty parking charges because they were delayed getting home. This is because the EU regulations do not cover these associated costs.
Travel insurance policies and claims through credit cards are also extremely unlikely to cover these extra costs.
"We would suggest that travellers trapped abroad contact the car park operators individually and see if they would waive any fees incurred due to the extended delay," said Jacqueline Beadle, a solicitor at Gullands in Kent.
"If you leave it until you return you may have little or no choice but to pay up."
Some car park operators are waiving fees for those who were delayed. For example, airport operator BAA said that it would not charge for those who overstayed at its official car parks.
Passengers should present travel documents which show their original intended return date and parking ticket to the customer service desk at the exit to the car park.