Aircraft manufacturing is an important industrial sector in Russia, employing around 355,300 people. The dissolution of the Soviet Union led to a deep crisis for the industry, especially for the civilian aircraft segment. The situation started improving during the middle of the first decade of the 2000s due to growth in air transportation and increasing demand. A consolidation programme launched in 2005 led to the creation of the United Aircraft Corporation holding company, which includes most of the industry's key companies. The Russian aircraft industry offers a portfolio of internationally competitive military aircraft such as MiG-29 and Su-27, while new projects such as the Sukhoi Superjet 100 are hoped to revive the fortunes of the civilian aircraft segment. In 2009, companies belonging to the United Aircraft Corporation delivered 95 new fixed-wing aircraft to its customers, including 15 civilian models. In addition, the industry produced over 141 helicopters. Russia had 24 aircraft manufacturers at the outbreak of war, but they did not have the materials or the capacity to replace the aircraft that were lost. In particular they were dependent on foreign engines. It produced 1893 aircraft and imported 883 from 1914 to 1916, but it only produced 920 engines in this period while importing 2326. Production declined sharply after the February Revolution, and had virtually ceased when Russia left the war in 1918. The most famous aircraft produced during this period was the Sikorsky Ilya Muromets, the first four-engine bomber to equip a dedicated strategic bombing unit. This heavy bomber was unrivalled in the early stages of the war, as the Central Powers had no comparable aircraft until much later. During World War I, Russia lost only one Sikorsky Ilya Muromets to enemy action in more than 400 sorties. In the Soviet planned economic system, free market competition between companies was seen as wasteful. The Soviet system was instead multi-tiered, the chief components of which were design bureaus, known as OKBs, and manufacturing complexes.