The BA 747 was taken from Heathrow to Cardiff via the Atlantic to see if it could safely fly, despite the ash cloud from the Icelandic volcano.
A BA spokesman said the aircraft encountered no difficulties.
Meanwhile, Cardiff Airport is to remain shut until at least 0100 BST on Tuesday because of the ash.
Flights in the UK and across Europe have been grounded after an Icelandic volcano erupted last Wednesday.
The BA test flight took off from London Heathrow Airport at 1755 BST on Sunday before flying 550 miles over the Atlantic Ocean and returning to Cardiff airport two and three-quarter hours later.
BA's chief executive Willie Walsh was on board along with the director of flight operations and the general manager of engineering.
The plane is undergoing a full technical analysis at BA's engineering base in the Vale of Glamorgan.
Results of the checks are not expected until later in the day.
A Cardiff Airport spokesman said managers there would be meeting airline and tourism chiefs to draw up plans for when flights started again.
One of the issues will be deciding on priorities, as to whether to concentrate on repatriating stranded passengers or carry on normal schedules.
The spokesman said airlines did not have many extra planes available.
Passengers on package holidays would be looked after by tour operators, effectively extending their holidays, but independent travellers would have more of a problem, he added.
Ferry operators in Wales have seen significant increases in passenger numbers since the National Air Traffic Service (Nats) halted all flights in the UK.
Rail operators have added extra capacity to services to Holyhead in Anglesey and Fishguard in Pembrokeshire.
Ferris Coaches, which operate out of Nantgarw in south Wales, are sending four double-decker buses to Spain on Monday to collect people in resorts there, and more will be despatched on Tuesday and Thursday.
The company's Jason Ferris said they sold 300 seats in four hours on Sunday and had a waiting list of 200 people.
"The problem I've got is getting drivers. It's on our peak season so driver availability isn't great," he said.
"We're calling up part time drivers and have some based in the south of France.
"But I had so many calls yesterday if I had 100 coaches I could have filled them. I've never known anything like it, it's unbelievable."
The company is dropping people off in Reading, Swindon and Bristol en route to Cardiff.
The Foreign Office website (www.fco.gov.uk) contains advice for stranded UK citizens.
UK citizens needing consular assistance can also contact the embassy in the country they are in. Contact details are available on the Foreign Office website.
An emergency number - 020 7008 0000 - is available for relatives of those stranded who are concerned about their safety or well-being.