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 1
[{'name': 'Boeing 737-800'}]