TRADING patterns of a small number of air shippers in China dominate the market, and any analysis of imports and exports must take this into account, advised Seabury Group managing director Gert-Jan Jansen.

China has 375,000 shippers importing and exporting by air, but high tech products dominate and 49 per cent of that value is handled by 10 shippers, Mr Jansen told the recent IATA World Cargo Symposium in Shanghai.

He expected China air freight would be weak in the next two months, citing the purchasing manager's index (PMI) that tracks factory output, which has been poor for the past couple of months.

"In the medium term, however, we expect trade to pick up and grow five per cent a year on the major US, EU, and Asia trade lanes for the next five years," he said.

"In value, the top 10 shippers are larger than the rest of the shippers in China combined, and that means we need to be careful when looking at China as a whole.

We need to appreciate just how large these shippers are and how they are behaving rather than make general statements about the country," said Mr Jansen.

The top five, Foxconn, Samsung, Huawei, Pegatron and Nokia, are all are in the business of smartphones, or tablets, but their supply chain are very different, reported Newark's Journal of Commerce.

Foxconn sends almost all its exports by air, Pegatron does the same. Samsung uses many more trucks exporting to Southeast Asia, Huawei is the only Chinese company in the top five and utilises road and ocean to a much more than air.

Destinations differ among the top players, Mr Jansen said. Foxconn exports to the developed markets in the US, EU and Asia, while Huawei exports to the Middle East and South Asia. Different products for different markets using different means of transport.

But Mr Jansen also noted that these mega exporters are mega importers too.

"There is no other company in China importing more than Foxconn. They need machinery for their factories. Large telecom producers are very large importers of semiconductors or other components, and capital equipment," said Mr Jansen.

Seasonality plays a big role too. China has a fourth quarter peak season, but that does not necessarily extend to shippers," he said.

"Foxconn is seasonal, too, but its seasonal pattern is very different from the seasonal pattern of Pegatron or Samsung," Mr Jansen said.

There is also geographic factors to consider. Panasonic operates in Liaoning, Jiangsu, Shanghai, Beijing, and Guangdong, but all the factories produce different things - audio-video in Liaoning, electrical generators in Jiangsu and mobile phones and devices in Beijing.

Mr Jansen said any analysis first needed to examine where certain mega shippers and the location of their factories.