Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request.

### Instruction:

Convert text to sql: What are the different pilot names who had piloted a flight in the country 'United States' or in the airport named 'Billund Airport'? | airport : id , city , country , iata , icao , name | operate_company : id , name , type , principal_activities , incorporated_in , group_equity_shareholding | flight : id , vehicle_flight_number , date , pilot , velocity , altitude , airport_id , company_id | flight.company_id = operate_company.id | flight.airport_id = airport.id | 

### Response:

select distinct _ from _ where _ | select distinct flight.pilot from airport join flight on airport.id = flight.airport_id where airport.country = 'United States' or airport.name = 'Billund Airport'