For the flight from ATL to PHL on 2018/8/1 that scheduled local departure time as "2040", which air carrier does this flight belong to?
flight from ATL refers to ORIGIN = 'ATL'; flight to PHL refers to DEST = 'PHL'; on 2018/8/1 refers to FL_DATE = '2018/8/1'; local departure time refers to CRS_DEP_TIME; CRS_DEP_TIME = '2040';
SELECT T2.Description FROM Airlines AS T1 INNER JOIN `Air Carriers` AS T2 ON T1.OP_CARRIER_AIRLINE_ID = T2.Code WHERE T1.FL_DATE = '2018/8/1' AND T1.ORIGIN = 'ATL' AND T1.DEST = 'PHL' AND T1.CRS_DEP_TIME = '2040' GROUP BY T2.Description
CREATE TABLE IF NOT EXISTS "Air Carriers"
(
    Code        INTEGER
            primary key,
    Description TEXT
);
CREATE TABLE Airports
(
    Code        TEXT
            primary key,
    Description TEXT
);
CREATE TABLE Airlines
(
    FL_DATE               TEXT,
    OP_CARRIER_AIRLINE_ID INTEGER,
    TAIL_NUM              TEXT,
    OP_CARRIER_FL_NUM     INTEGER,
    ORIGIN_AIRPORT_ID     INTEGER,
    ORIGIN_AIRPORT_SEQ_ID INTEGER,
    ORIGIN_CITY_MARKET_ID INTEGER,
    ORIGIN                TEXT,
    DEST_AIRPORT_ID       INTEGER,
    DEST_AIRPORT_SEQ_ID   INTEGER,
    DEST_CITY_MARKET_ID   INTEGER,
    DEST                  TEXT,
    CRS_DEP_TIME          INTEGER,
    DEP_TIME              INTEGER,
    DEP_DELAY             INTEGER,
    DEP_DELAY_NEW         INTEGER,
    ARR_TIME              INTEGER,
    ARR_DELAY             INTEGER,
    ARR_DELAY_NEW         INTEGER,
    CANCELLED             INTEGER,
    CANCELLATION_CODE     TEXT,
    CRS_ELAPSED_TIME      INTEGER,
    ACTUAL_ELAPSED_TIME   INTEGER,
    CARRIER_DELAY         INTEGER,
    WEATHER_DELAY         INTEGER,
    NAS_DELAY             INTEGER,
    SECURITY_DELAY        INTEGER,
    LATE_AIRCRAFT_DELAY   INTEGER,
    FOREIGN KEY (ORIGIN) REFERENCES Airports(Code),
    FOREIGN KEY (DEST) REFERENCES Airports(Code),
    FOREIGN KEY (OP_CARRIER_AIRLINE_ID) REFERENCES "Air Carriers"(Code)
);
