How many matches have taken place?
select count(*) from match
How many of them have been won by the same aircraft?
select count(*) from (select t1.aircraft, count(*) from aircraft as t1 join match as t2 on t1.aircraft_id = t2.winning_aircraft group by t2.winning_aircraft having count(*) > 1)
Which aircrafts?
select t1.aircraft from aircraft as t1 join match as t2 on t1.aircraft_id = t2.winning_aircraft group by t2.winning_aircraft having count(*) >= 2