SELECT T2.name FROM Certificate AS T1 JOIN Aircraft AS T2 ON T2.aid  =  T1.aid GROUP BY T1.aid ORDER BY count(*) DESC LIMIT 1
What are the names of the aircraft that the least people are certified to fly?
SELECT T2.name FROM Certificate AS T1 JOIN Aircraft AS T2 ON T2.aid = T1.aid GROUP BY T1.aid ORDER BY count ( * ) DESC LIMIT 1
select t2 . name from certificate as t1 join aircraft as t2 on t2 . aid = t1 . aid group by t1 . aid order by count ( * ) desc limit value
What are the names of the aircraft that the least people are certified to fly ?