Bombardier has won a trade case in the United States, overturning a decision to impose damaging tariffs on imports of its C-Series aircraft.
The UK government had suspected that the Canadian aircraft manufacturer would lose. Unions had feared sales and UK jobs would be hit.
But in a surprise ruling, the US International Trade Commission (ITC) rejected a complaint brought by Boeing.
The ITC voted 4-0 in favour of Bombardier.
They ruled that there was no injury to US manufacturers, effectively forcing the US Commerce Department to reverse course on retaliatory countermeasures designed to protect Boeing.
Tariffs of 292% will not now be imposed on orders of C-Series planes by American carriers.
About 50 companies in the UK supply Bombardier with parts for the C-Series.
One thousand jobs in Belfast, where the wings for the plane are made, depend on its success.
A spokesperson for Bombardier said the ITC’s decision was “a victory for innovation, competition and the rule of law.”
“The C-Series is the most innovative and efficient new aircraft in a generation.,” they said.
“Its development and production represent thousands of jobs in the United States, Canada, and the United Kingdom.”
A spokesperson for Boeing said it was “disappointed” by the ITC’s decision and that it would “review the detailed conclusions when they are released”.
Steve Turner, Unite assistant general secretary said it was “the right decision”.
He said Bombardier workers in Northern Ireland and throughout the supply chain in UK “will be breathing a huge sigh of relief”.