Context: Following the war, some of these military airfields added civil facilities for handling passenger traffic. One of the earliest such fields was Paris – Le Bourget Airport at Le Bourget, near Paris. The first airport to operate scheduled international commercial services was Hounslow Heath Aerodrome in August 1919, but it was closed and supplanted by Croydon Airport in March 1920. In 1922, the first permanent airport and commercial terminal solely for commercial aviation was opened at Flughafen Devau near what was then Königsberg, East Prussia. The airports of this era used a paved "apron", which permitted night flying as well as landing heavier aircraft.

Question: Following the war, why did some military airfields add civil facilities?
Answer: for handling passenger traffic

Question: Which airport near Paris was one of the first to add civil facilities for handling passenger traffic?
Answer: Le Bourget Airport

Question: What was the first airport to operate scheduled international commercial services?
Answer: Hounslow Heath Aerodrome

Question: When did the Hounslow Heath Aerodrome begin to operate scheduled international commercial services?
Answer: August 1919

Question: What did airports use to permit night flying as well as landing heavier aircraft?
Answer: a paved "apron"

Question: When was the Paris - Le Bourget Airport first opened?
Answer: Unanswerable

Question: What was the Paris - Le Bourget Airport replaced by?
Answer: Unanswerable

Question: When did Houndlow Heath Aerodrome replace Croydon Airport?
Answer: Unanswerable

Question: When was Croydon Airport opened in Flughafen Devau?
Answer: Unanswerable

Question: What was used at military airfields in 1919?
Answer: Unanswerable