Hampered by poor co-ordination and a meagre staff, China did not immediately exploit the capability of its satellites to search for the missing Malaysian airliner, according to a Chinese scientist.
It was one of several potential problems raised by researchers, who are as frustrated as the public in the search for Malaysia Airlines flight 370.
When the Boeing 777 was en route from Kuala Lumpur to Beijing last Saturday, no Chinese satellites were observing it, said Dr Chi Tianhe, a researcher in satellite imaging with the Chinese Academy of Sciences who took part in the search.
Several hours after Malaysia Airlines announced that the plane had disappeared, China used its satellites to scour the waters between Vietnam and Malaysia, state media said. They were part of a multinational effort using military equipment. The search has failed to find survivors, wreckage or debris.
Watch: What we know about Malaysia Airlines flight MH370
"Chinese satellites' real-time surveillance capability will likely be strengthened after this incident," said Chi, a professor with the academy's Institute of Remote Sensing and Digital Earth in Beijing.
Chi said his biggest regret was that while China had enough satellites to monitor a large area around the clock, including the search zone, the job had not been done. Monitoring every bit of land and sea would require a dedicated staff, he added.
The failure of the search has raised questions over its field and strategy, and its multinational co-ordination.
Professor Wu Dong, a satellite remote-sensing expert with the Ocean University of China in Qingdao, said the lack of satellite evidence of the plane suggested that the designated search zones could be wrong.
Professor Xie Tao, an expert in ocean satellite remote-sensing at Nanjing University of Information Science and Technology, said it was possible that the resolution of the satellites doing the search was not high enough, an assertion that Chi disputed.
"The waves would also distort microwave images and make analysis difficult," Xie said. And time was of the essence. "The longer the search takes, the farther the debris would be carried away by currents from the crash site."
For three days, Chinese researchers have employed high-resolution satellite imaging equipment to search for the Boeing aircraft. This has included satellites with many different sensors, including high-resolution optical telescopes, infrared cameras, synthetic aperture radar and microwave detectors.
The search project has also used military satellites with classified technological details. In addition, China has paid overseas commercial satellite companies to use their advanced satellites and to obtain their data.
The satellite equipment allowed researchers to examine specific areas of the sea for wreckage and debris day and night, under all kinds of weather conditions, Chi said.
Chi would not comment as to the size of objects that the satellites could detect but added that the resolution was "definitely high enough for the job".
Some US and Canadian satellites can distinguish an object as small as half a metre in size, but the ocean waves could make precise detection difficult. "If the object is non-metalic, such as plastic, it would be very difficult to spot with radar," Xie said.
While civilian satellites might have difficulty finding debris, military spy satellites should be able to do the job because they are designed to search for very small targets, Wu said.
Chinese warships have prowled the sea using powerful surface radar to detect objects on the sea's surface, and sonar to find underwater wreckage.
Wu said it was possible, judging from the lack of wreckage, that the plane made a successful water landing, but then sank to the ocean floor in one piece.
"But if the crew achieved such a miracle, why didn't they radio for help?" Wu asked. "From a technical point of view, I cannot find a good explanation for the complete disappearance."
The lack of evidence also frustrates Chi. "If such a large plane had fallen in the ocean, it would leave some signs on the surface," he said. "The plane seems to have disappeared completely. To us it is unreasonable."