Show names for all aircrafts of which John Williams has certificates.
SELECT T3.name FROM Employee AS T1 JOIN Certificate AS T2 ON T1.eid  =  T2.eid JOIN Aircraft AS T3 ON T3.aid  =  T2.aid WHERE T1.name  =  "John Williams"
SELECT T3.name FROM Employee AS T1 JOIN Certificate AS T2 ON T1.eid  =  T2.eid JOIN Aircraft AS T3 ON T3.aid  =  T2.aid WHERE T1.name  =  "John Williams"
[{'name': 'Boeing 737-800'}, {'name': 'Boeing 757-300'}]