WASHINGTON, US - A bill to modernise the United States air traffic system, increase safety oversight and improve customer service was derailed on Tuesday by US Senate wrangling over attempts to include unrelated measures.

The massive multiyear blueprint authorising Federal Aviation Administration (FAA) programmes was undercut by partisan disagreement, and Democratic leaders failed to win a procedural motion that would have brought the bill to a final vote.

Some industry and congressional insiders said it was possible, but not likely, that proponents could reintroduce the package in the future, stripped of contentious and unrelated tax, pension, labour, and transit financing issues.

'Frustrated, perplexed and deeply disappointed are just some of the words that I would use to describe the Senate's inability to move forward on this bill,' said John Rockefeller, a West Virginia Democrat and chairman of the Senate aviation subcommittee. 'I remain hopeful that we can work things out.'

Mr Rockefeller's counterpart in the House of Representatives, aviation subcommittee chairman Jerry Costello of Illinois, called the Senate's inaction a missed opportunity.

'With the summer travel season almost upon us and well-publicised safety breakdowns at the FAA, it is critical that we pass a final version of this legislation,' Mr Costello said.

The House has already approved a similar measure.

But the Senate bill included updated provisions to tighten oversight of airline safety practices in response to questions this spring about FAA oversight.

Hundreds of commercial aircraft were grounded and thousands of flights were cancelled in the United States in March and April because of missed safety inspections. --Reuters