The last RAF aircraft to be repaired by the Ministry of Defence (MoD) at St Athan has flown out, ending 75 years of maintenance at the site.
The remaining 200 workers at the base will be made redundant after the VC10 left at 15:50 GMT on Thursday.
Vale of Glamorgan MP Alun Cairns called for the skills of the workforce to be kept within the area.
The Welsh government said it was working to attract new companies, with interest in a new enterprise zone.
Mr Cairns said he was sorry to see the last aircraft leave the site, but the “expert knowledge base” needed to be retained locally.
“I’m in touch with the MoD regarding the plans for the super hangar and am optimistic about the outcome,” said the MP.
Paul Lindsay of the Wales Aerospace Forum said it was “a sad day” and “a great disappointment” for the local community.
“There are positives in that we’ve had 75 good years,” he said.
“But the disappointment is that between the Welsh government and the MoD they have invested £240m there over the past 10 years.
“Let’s hope that collectively they decide what the future is for St Athan. The Welsh government and the MoD are working hard to fill the gap.”
St Athan’s history as an aircraft maintenance base dates back to 1938.
Just before and during World War II many different types of aircraft were assembled, test flown and maintained there by a staff of 14,000, and the base inevitably became a target for German bombers.
By the mid-1990s there were 3,500 engineers repairing fighter jets.
But since then the St Athan site has since endured more than a decade of uncertainty and failed attempts to secure skilled jobs.
In 2000 the Red Dragon Project began, aimed at modernising the ageing MoD facilities there, along with the construction of a £77m super hangar for fast jet repair.
The main tenant for the new super hangar was to be the Defence Aviation Repair Agency, Dara.
Gradually wound down
But in 2005, UK ministers announced they were closing the fast jet business at St Athan, with the loss of hundreds of jobs.
In March 2009 the National Audit Office and the Wales Audit Office criticised both the MoD and Welsh authorities after it had cost the taxpayer £113m and failed to deliver thousands of jobs.
The then Defence Minister Quentin Davies revealed in November 2009 that nearly 340 jobs would be lost at the base in south Wales by June 2013 at the latest.
In October 2010, a £14bn defence training academy which would have created 2,000 jobs at St Athan was scrapped as part of 8% cuts by the UK government to the defence budget.
At that time there were around 400 civilian staff left at the base.
But the operation has been gradually wound down as the contract to service the VC-10 tanker aircraft came to an end.
Mr Lindsay added: “The buildings are there. It’s available. Let’s hope somebody else comes.”
The Welsh government said there was significant private sector interest in the newly designated St Athan Enterprise Zone.
It said it was working to attract new companies to the area capable of creating sustainable jobs for local people.
A spokesman said Cardiff Airport and other key employment sites and development proposals in the immediate vicinity were now being included in the enterprise zone.
“Potential employers are made aware of the skills mix available,” said the spokesperson.
Sourced by BBC