The third Mitsubishi MRJ flight test airplane (FTA-3) flew for the first time on Tuesday, meaning four flying prototypes now participate in the model’s certification program. FTA-3 took off from Nagoya Airfield in Japan at 10:18 a.m. local time and landed at 12:22 p.m. Six team members took part in the flight. 

The flight took place three days after Mitsubishi MRJ FTA-4 arrived at Moses Lake, Washington, to join FTA-1 for U.S.-based flight tests. That airplane took off from Nagoya Airfield at 9:35 a.m. Japan time on November 15 and arrived at Grant County International Airport in Moses Lake 1:46 p.m. Pacific Standard Time on November 18. FTA-4’s trip to the U.S. took it to Guam International Airport, Majuro International Airport in Republic of the Marshall Islands, Honolulu International Airport and San Jose International Airport in California. It took 18 hours and 43 minutes to fly the 7,600 nautical mile route.

The milestones show progress by a flight-test program that has struggled to meet targeted schedules since FTA-1 flew for the first time last November. Last month Mitsubishi confirmed press reports out of Japan that it has communicated with MRJ launch customer All Nippon Airways about another possible delay in first deliveries due to “technical reasons.” If the manufacturer fails to deliver the first airplane by mid-2018, it would mark the fifth major delay for the program.