Gao Yuanyang, director of the General Aviation Industry Research Center at Beihang University, said the government did not consider including the general aviation sector in the emergency response system in the past, and it also lacked information about general aviation aircraft locations and numbers.

Military experts believe it is much easier to use the military fleet in the earthquake zone, while civilian helicopters cannot be brought into the military command system, as this would lead to congested airspace.

Civilian helicopters are also usually smaller than military helicopters, which can carry more materials and passengers. Military helicopters usually install more advanced equipment for rescue efforts.

Ryan McFeaters, general manager of Sikorsky Aircraft China, the US helicopter manufacturer, said some common equipment, such as hoists, searchlights and a specialized search and rescue automatic flight control system, which helps pilots perform rescue missions in challenging environments, are needed in such situations.

"Reliability and all-weather capability are also the most important performance characteristics of the helicopter for search and rescue," he said.

But Gao, from Beihang University, said that the exclusion of the general aviation sector from the emergency response system means the sector's potential has not been well applied.

Wu agreed, saying his pilots know the terrain in Ya'an well and his helicopters are small and flexible compared with military ones.

Wu Jingkui, vice-president of North Asia sales and market development for the Cessna Aircraft Co, believes depending only on military helicopters for rescue and relief work is not the answer.