(Bloomberg) — Delta Air Lines Inc. planes were involved in three wingtip collisions in separate low-speed accidents over two days at New York's John F. Kennedy airport, leaving one man injured.

Low-speed collisions

The National Transportation Safety Board said on Thursday that it's investigating the accidents, indicating that they may be more serious than usual or that there may be a pattern. Low-speed collisions between planes and other aircraft or vehicles on the tarmac and taxiways occur relatively regularly and often don't cause significant damage or injuries.

The first accident occurred at 7:12 p.m. on Aug. 15, when a Boeing Co. 737 operated by Delta and an American Airlines Group Inc. Boeing 757 each were taxiing out for departure. The Delta plane's left wing touched the American jet's tail. No one was injured, according to the Federal Aviation Administration.

Truck driver treated at hospital

About 4:30 p.m. the next day, a JFK ground crew was directing a Delta CRJ regional aircraft in a terminal ramp area when its left wing touched the right wing of a second Delta CRJ plane that was parked at the gate. An hour later, the left wingtip of a Delta MD-88 aircraft touched a flatbed truck as it was turning into a ramp area.

While the federal agency reported no injuries, Port Authority of New York and New Jersey spokesman Joseph Pentangelo said the driver of the truck, described as an aircraft tug vehicle, was treated at a hospital and released.