SELECT
   COUNT(flights.flight_id) AS flights_amount
FROM
    flights
INNER JOIN aircrafts ON aircrafts.aircraft_code = flights.aircraft_code
WHERE
    (aircrafts.model LIKE '%Boeing%' OR aircrafts.model LIKE '%Airbus%')
    AND CAST(flights.departure_time AS date) BETWEEN '2018-09-01' AND '2018-09-30'
GROUP BY
    CASE WHEN model LIKE '%Boeing%' THEN 'Boeing'
         WHEN model LIKE '%Airbus%' THEN 'Airbus'
    END;