Beijing’s main airport had the lowest ranking for on-time departures last month with less than one in five flights leaving on schedule as military controls of airspace and an expanding fleet add to congestion.

Shanghai had the second-worst among the 35 busiest international airports in June, according to rankings by industry researcher FlightStats Inc. Tokyo’s Haneda airport was the top performer with 95 percent of flights leaving on time, followed by the Japanese capital’s Narita.

About 18 percent of 22,019 flights departing from Beijing Capital International Airport were on time, while Shanghai Pudong International airport had a rate of about 29 percent, Portland, Oregon-based FlightStats said. FlightStats records a delay if an aircraft fails to take off within 15 minutes of the scheduled gate time.

Air China Ltd., China Eastern Airlines Corp. and other carriers have expanded their fleets as economic growth spurs travel demand in China, where the air force allots only 20 percent of air space to civil aviation. Traffic congestion is set to worsen as the nation’s commercial aircraft fleet is projected to double in the next seven years.

China is expected to have 4,200 commercial aircraft in 2020, compared with the current fleet size of 2,001 with 46 airlines, Li Jiaxiang, head of the Civil Aviation Administration of China, said in May.

JFK, Heathrow

More than 42 percent of flights at Beijing airports experienced excessive delays, defined as flights that arrive or depart at the gate 45 minutes or more after the scheduled time, the report said.

Amsterdam airport ranked third out of the 35 facilities, with an on-time rate of 84 percent, while John F. Kennedy International Airport in New York was 26th with 66 percent. London Heathrow was ranked 21 with a rate of 72 percent.

Hong Kong International Airport was 29th, with 64 percent of flights out of the 12,417 departing on time, FlightStats said. Singapore Changi Airport ranked 10th, with a 78 percent of on-time performance.

Among Asian airlines, China United Airlines Co. is the worst of the 41 carriers surveyed with 27 percent of flights arriving on time. China Eastern ranked 33rd, with a punctuality rate of 57 percent, and China Southern at 29th, with a rate of 62 percent.

The top-ranked Asian carrier was Air Busan with an on-time rate of 97 percent, FlightStats said.

–Editors: Vipin V. Nair, Dave McCombs

To contact the reporter on this story: Janet Ong in Taipei at jong3@bloomberg.net

To contact the editor responsible for this story: Anand Krishnamoorthy at anandk@bloomberg.net