The Icelandic volcano is causing global travel chaos
Formula 1 teams are concerned that the air travel chaos caused by the volcanic ash cloud over Europe could affect their plans for the next race.
Teams and other personnel face problems returning to Europe from Sunday's Chinese Grand Prix as most flights from Shanghai to Europe have been cancelled.
But the biggest concern is preparing cars for the Spanish race on 9 May.
"We haven't had word from freight yet and we've got to get the cars back," McLaren boss Martin Whitmarsh said.
"The cars and equipment have been away for some time and we're looking forward to getting them back in the factories as quickly as possible and servicing the cars properly.
When the airport's open we'll take them home, until that day we'll be staying here
Formula 1 Management
"We have a range of upgrades that we hope to put on for Barcelona that could be chaotic if we don't get the freight back.
"As for the people, they are incredibly resourceful and we'll find a way back, it just might be more tortuous than usual."
McLaren's two British drivers, Jenson Button and Lewis Hamilton, had not planned to return to Europe immediately anyway and others - including Red Bull's Mark Webber - are heading back via the Middle East.
F1 freight is transported on charter flights, with six Boeing 747 'jumbo jets' carrying the cars, so F1 boss Bernie Ecclestone's Formula 1 Management company are not beholden to commercial airlines' decisions on whether to fly to Europe or not.
Asked on BBC One at the Chinese Grand Prix on Sunday about the looming problem over the Spanish race, Ecclestone joked: "We'll hold it here."
Alan Woollard, who runs FOM's travel operation, said: "When the airports open we'll take them home, until that day we'll be staying here. Hopefully we'll get out of here by the end of the week."
Red Bull team manager Jonathan Wheatley added: "I've got 76 people here from seven or eight countries and 40,000kg of freight, so I would be lying if I said if I wasn't concerned."
Among the options being explored by teams to get their personnel back to Europe is booking them on the Trans-Siberian railway.
BBC F1 commentator Jonathan Legard said McLaren were chartering a flight back to Spain on Wednesday, from where they will take buses back to the UK, and that other teams may join them.
And Lotus team principal Tony Fernandes said on his
that personnel from the Ferrari, Renault, Mercedes, Sauber and Toro Rosso teams were flying on his Air Asia airline to Malaysia before heading back to the UK on a special charter when the airports open.
Some journalists have found a route via New York, Portugal, Spain and then a ferry to Britain; another was considering a journey that would involve taking a train to Britain from Turkey. And a Portuguese reporter is travelling back to Lisbon via Kuala Lumpur, Bahrain, Cairo and Casablanca.
The BBC F1 team is also caught up in the situation, with an attempt to get some on to a flight to Milan on Sunday night failing.
The UK is enduring a fourth day as a virtual no-fly zone, as the travel chaos caused by volcanic ash drifting from Iceland shows no sign of ending.
The problem has caused the postponement of the MotoGP race scheduled for Motegi in Japan next weekend.
Flight restrictions have been extended until at least 0100 BST on Monday and forecasters say the ash cloud could remain over the UK for several more days.
The problem is being caused by a continuing eruption of the Eyjafjallajokull volcano in southern Iceland, which is pumping volcanic ash high into the atmosphere.
Usually, the prevailing south-westerly wind would take the ash cloud away from Europe and over the polar region, but a high-pressure area is bringing it over Europe, where it is sitting and barely moving as the ash spreads.