PHOENIX (KPHO) - The number of airborne drug smugglers identified flying over the southwest border has nearly doubled in two years, according to officials from Immigration and Customs Enforcement.

During the last fiscal year, authorities tracked nearly 240 ultralight aircraft, retrofitted to carry hundreds of pounds of marijuana, as they crossed from Mexico into the United States.

"What they're doing is flying in, then dropping [marijuana bales] from their ultralights still in the air to a ground crew," said Matthew Allen, the Special Agent in Charge of the Phoenix ICE office.

Allen told CBS 5 Investigates the first ultralight his agency first spotted the aircraft in 2008, when one attempted to land in the desert near Marana. Allen believes this new form of smuggling shows the drug cartels are adapting their methods, as a result of increased enforcement along the border.

"The way I often express it is we're raising the cost of doing business for them because they're having to abandon their tried and true smuggling techniques," said Allen.

So far this year, ICE agents have arrested nearly 40 suspects connected to ultralight smuggling.

http://www.kpho.com/story/15071246/airborne-smugglers-rising-in-arizona