Incumbents are just as hard to dislodge in the market for smaller “regional” jets (ones with up to around 100 seats), which is dominated by Bombardier and Embraer of Brazil, but which COMAC, UAC’s Sukhoi subsidiary and Mitsubishi of Japan are all trying to break into. COMAC’s regional jet, the ARJ21, had its first test flight in 2008, but because of concerns about cracks in its wings and dodgy wiring it has still not been certified for commercial flights in America. Mitsubishi’s MRJ and Sukhoi’s Superjet were also delayed by technical problems.