The supporters' claim was that _______.

When the British government announced the
introduction of Concorde flights, there was a great
deal of opposition from environmental groups, who
even tried to block several major roads in the vicinity
of the airport. But the government soon dismissed
the opposition, claiming that some conventional
aircraft were far noisier by comparison and that
much of the opposition to the Concorde was
baseless. Supporters of the Concorde also pointed
out that there had been similar opposition when jet
aircraft were first introduced, and that despite some
negative scientific reports there were other reports to
the contrary.