Translate the following question to SQL: What is the velocity of the pilot named 'Thompson'?

Schema: CREATE TABLE airport (
    id INT   PRIMARY KEY,
    City TEXT,
    Country TEXT,
    IATA TEXT,
    ICAO TEXT,
    name TEXT,
    UNIQUE (id)
);

CREATE TABLE operate_company (
    id INT   PRIMARY KEY,
    name TEXT,
    Type TEXT,
    Principal_activities TEXT,
    Incorporated_in TEXT,
    Group_Equity_Shareholding REAL,
    UNIQUE (id)
);

CREATE TABLE flight (
    id INT   PRIMARY KEY,
    Vehicle_Flight_number TEXT,
    Date TEXT,
    Pilot TEXT,
    Velocity REAL,
    Altitude REAL,
    airport_id INT,
    company_id INT,
    UNIQUE (id),
    FOREIGN KEY (company_id) REFERENCES operate_company(id),
    FOREIGN KEY (airport_id) REFERENCES airport(id)
);
user
SELECT avg(velocity) FROM flight WHERE pilot  =  'Thompson'
assistant