The 555-seat A380 superjumbo is one of Europe's most prestigious manufacturing projects, and a hiccup at this stage would be a gross embarrassment for the country concerned. Complete sections of the first plane are due to be picked up over the next few weeks from sites in the UK, Germany and Spain and shipped to the French port of Bordeaux, for onward transport by barge to an assembly plant in Toulouse.
The UK's main contribution is BAe Systems' giant wing fabrication facility in Broughton, near Chester. Completed wings 36 metres long and 11 metres wide are to be taken by barge along the river Dee to the port of Mostyn, where they will be transferred to a sea-going vessel for shipment to Bordeaux.
That, at least, was the plan. But it was upset in early March when the Environment Agency announced that dredging consents sought by the port of Mostyn had been refused.
The port had wanted a major annual dredging operation in its approach channel to open up round-the-clock access for large vessels such as the Airbus ro-ro. But the regulators decided that it had failed to demonstrate that the ecological integrity of the estuary's designated wildlife site would not be threatened - and themselves believe that the operation could cause the loss of up to 50 hectares of sandbanks every year.
The Dee estuary is home to 120,000 wading birds and waterfowl over the winter, and has as many protective designations as any habitat in Britain. It has long been a Ramsar site, making it a wetland of international importance for birds, but for legal purposes the critical designations are as a special protection area under the 1979 EU Directive on birds and a proposed special area of conservation under the 1992 Directive on habitats.
Projects liable to affect a site designated under either Directive must not be authorised if they may "adversely affect the integrity" of the site. Only if no alternative solutions can be found may a damaging project proceed, and then only where there are "imperative reasons of overriding public interest". In such a case, compensatory measures must be taken.
Responding to the Environment Agency's announcement, shadow Welsh Secretary Bill Wiggin said he was "astounded" by the decision and branded it the latest in "a long line of broken promises" by the Government. Thousands of jobs were at risk, and he called on Welsh Secretary Peter Hain to intervene.
Mr Hain has needed no encouragement. He said he was "horrified" by the prospect of Mostyn being "deprived" of dredging. "We all want our environment protected but there has to be a sense of proportion. The Environment Agency must realise there are wider public interests at stake here." The "overwhelming public interest" was to maintain the 1,200 jobs at Broughton.
Mr Hain provided the cue for the north Wales group of six Labour members of the Welsh Assembly, who quickly formed a campaign for the dredging to be given the go-ahead. All six argued that there is "overwhelming" or "overriding" public interest in doing so. Alyn and Deeside AM Carl Sergeant commented: "I am extremely angry that this decision has come so late in the day," and urged members of the public to write in support of the campaign.
The Liberal Democrats joined in. North Wales AM Eleanor Burnham said: "We do want to protect habitats and nature", but added: "We human beings are a species too."
Airbus has not been responding to inquiries, but the company's senior vice-president for manufacturing in the UK, Brian Fleet, has not held back in statements to the local media.
Mr Fleet put the blame squarely on the regulators, complaining: "It's a bit late to tell us that there's a problem now." Laying it on thick, he warned that "Britain's involvement in the [Airbus] project could be over if Mostyn cannot dredge and we find ourselves landlocked."
"I don't even know why this is up for discussion," said Mr Fleet. "When Mostyn got permission to operate as a port, dredging should have been expected by the Environment Agency." And his punchline was: "We have enough beaches and deserted sandbanks in north Wales, we need the port."
The only senior figure seeking to exert a calming influence, and seemingly the only one to have familiarised himself with the legal issues, has been First Minister Rhodri Morgan.
Speaking at an aerospace conference at Broughton on 12 March, Mr Morgan said that a heavyweight contest with "hyper-Byzantine" rules was under way "between an exceptionally important industrial logistic chain and an exceptionally important estuary of huge environmental importance."
Mr Morgan stressed that Ministers could not intervene in the regulators' decisions because of the possibility of judicial review, and tacitly dismissed other politicians' calls for a quick decision on public interest grounds. Things had to be done by the book, he said, and the next step was to consider whether there were any alternatives to the refused dredging consents. Only if there were not could any overriding public interest be considered.
The First Minister also declined to use the Environment Agency as a punchbag. The Agency was in fact only one of three bodies which took the decision to withhold consent for the dredging operation. The Department of Transport and the Welsh Assembly government, which each have to give separate consents, also participated.
Moreover, they did so on the basis of advice from the Countryside Council for Wales that the operation should not proceed if breaches of the birds and habitats Directives were to be avoided.
Accusations that the Agency was to blame for slow decision-making and dropping a last-minute bombshell also appear to be very wide of the mark.
The port of Mostyn was revived after receiving planning permission to expand following a public inquiry in 1996. That permission allowed it to construct a new berth further out into the estuary and carry out some localised dredging, but did not approve dredging of the approach channel - the point at issue today.
In 2001, the port applied for and received consent for a one-off operation to dredge 175,000m3 of sand from the approach channel. But controversy really began when it followed up with another application to dredge twice as much as this every year. Nothing remotely on this scale was put to the test at the 1996 public inquiry.
The regulators responded by authorising a trial dredge last summer involving the use of tracer dye to pinpoint the fate of sand extracted from the approach channel and dumped further out in the estuary.
A report on the trial results was submitted by the port of Mostyn in December, just four months before the first Airbus shipment. The Agency says that the report "was inadequate in terms of analysis and justification, and it took considerable effort by all the regulators to fully interpret the data." The process was eventually completed in early February.
Complaints about the regulators springing a last-minute surprise scarcely stand up in the face of earlier events. The port's application for a dredging consent in 2001 ran into objections from wildlife conservation groups, serving notice of trouble ahead.
Tony Prater, conservation manager at the Royal Society for the Protection of Birds, says that refusal of the present consent was "clearly something that should have been seen coming a long time ago."
Serious doubts remain about whether Airbus had invested in a proper appreciation of the environmental implications of the wing shipments. The need for a major dredging operation was not mentioned in either its planning application for transport works at the Broughton end two years ago or at a meeting with conservation groups last year.
However, the controversy has flushed out an admission from Airbus that it does have contingency plans should its preferred transport option be blocked - though it has refused to disclose what they are.
The Dee Estuary Conservation Group, an umbrella body for 25 wildlife organisations, has called on Airbus to display flexibility. It is pressing the company to explain why it should require round-the-clock access to Mostyn when it is likely to use the port only twice a month. Adjustments to departure times of only a few hours to allow sailings at high tide would require much reduced dredging operations.
Another alternative might be to transfer the wings to a sea-going barge at Mostyn which could meet up with the Airbus ro-ro at a nearby port such as Liverpool or Birkenhead.
The regulators have set themselves a deadline around the end of March to conclude their consideration of alternatives. Only if they draw a blank will the discussion move on to questions of the public interest.
What nobody has been able to say authoritatively is whether the matter would then have to be referred to the European Commission, which in some circumstances effectively has the last word as to what constitutes "imperative reasons of overriding public interest". That is one eventuality which most parties will be anxious to avoid.