Freight traffic at New York's Kennedy International Airport fell 6.4 percent in May, the sharpest monthly decline at the major trans-Atlantic gateway in six months.

The drop included a 6.6 percent dive in JFK's international freight tonnage, a new sign that a weak shipping economy and rising jet fuel costs are hitting air trade.

Air cargo industry executives say that soaring jet fuel prices are pushing shippers and forwarders to cheaper ocean transport. With its sprawling maritime business, New York has ready alternatives to air transport and the airport figures suggest shippers are turning to container lines.

The decline in May left freight business at Kennedy Airport down 3.9 percent compared to the first five months of 2007, following a 2.9 percent drop for the full year last year.