(CNN) -- The Federal Aviation Administration has suspended two air traffic controllers from New Jersey's Teterboro Airport over Saturday's collision of two aircraft over the Hudson that killed nine people, a spokeswoman said Thursday.The controller handling the flight of a Piper PA-32 Saratoga carrying three people "was involved in apparently inappropriate conversations on the telephone at the time of the accident," spokeswoman Laura Brown said in a written statement.
In addition, "the supervisor was not present in the building as required," she said.
"While we have no reason to believe at this time that these actions contributed to the accident, this kind of conduct is unacceptable and we have placed the employees on administrative leave and have begun disciplinary proceedings," she said.
The National Transportation Safety Board is working with the FAA in investigating the Piper's collision with a sightseeing helicopter.
"These are serious violations of the FAA regulations," said Mary Schiavo, former inspector general for the Transportation Department.
The controller was on the phone with his girlfriend "after he cleared the pilot for takeoff," a source with knowledge of the investigation told CNN. "He was still on the phone at the time of the crash."
Killed aboard the plane were the owner and pilot, Steven Altman, 60, of Ambler, Pennsylvania; his brother, Daniel Altman, 49, of Dresher, Pennsylvania; and Daniel Altman's 16-year-old son, Douglas.
The Piper took off from a Philadelphia-area airfield Saturday morning and landed at New Jersey's Teterboro Airport before taking off again, this time bound for Ocean City, New Jersey.
The NTSB has said the pilot of the small plane was cleared electronically and handed off to Newark, New Jersey, air traffic controllers, a standard procedure.
However, Newark's control tower never got a verbal response from the pilot of the small plane. Controllers lost contact with the plane at 11:53 a.m., when it was at an altitude of about 1,100 feet, the NTSB said.
The controller put on leave was described as a long-time employee, the source said.
He and the supervisor face disciplinary action that could include their firing.
Also Thursday, FAA Administrator Randy Babbitt said the agency may re-issue advisories to pilots using the busy airspace over the Hudson River.
Pilots are urged to use a radio frequency dedicated to traffic in that corridor, to fly no faster than 140 knots, and to turn on their lights as they enter that airspace.
The victims aboard the helicopter were the pilot and five tourists from Bologna, Italy, part of a group of 10 Bologna-area residents who were in New York to help a couple celebrate their 25th wedding anniversary, said Giovanni Castellaneta, Italy's ambassador to the United States.
The celebrating husband and one of the couple's sons were killed in the crash, but the wife skipped the sightseeing flight to go shopping, another son told Italian news media.
The victims from Bologna were Michele Norelli, 51; Norelli's son Filippo Norelli, 16; Fabio Gallazzi, 49; Gallazzi's wife, Tiziana Pedroni, 44; and Gallazzi's son, Giacomo Gallazzi, 15.
Michele Norelli's wife, Silvia Rigamonti, decided to visit New York stores instead of seeing its sights from above, the couple's eldest son, Davide Norelli, told Italian media.
The pilot of the helicopter -- a Eurocopter AS350 -- was Jeremy Clarke, 32. He had worked for Liberty Helicopter Sightseeing Tours for about 1½ years and had logged 2,700 helicopter flight hours, NTSB Chairman Debbie Hersman said.
The helicopter was taking the five Italians on a 12-minute sightseeing tour around New York and had taken off from a heliport in midtown Manhattan shortly before the crash, Hersman said.
Hersman called the area "very complex airspace" near three major airports and a variety of other general aviation facilities.
In an effort to determine just how complex, the Federal Aviation Administration found that, in each of the eight days prior to the crash, an average of 225 aircraft operated at or below 1,100 feet within a 3-mile radius of the accident site, she said. Below that altitude, aircraft can operate under visual flight regulations.
The wreckage of the helicopter was pulled from the Hudson on Sunday, nearly intact. Investigators will focus on radio communications along the air corridor at the time of the crash and will examine any images contributed by the public.
Neither aircraft was required to carry electronic data recorders -- often referred to as "black boxes" -- that record cockpit voices and flight information on larger planes. But electronic navigational devices on board might retain information that could help investigators, Hersman said.
Liberty Helicopter Sightseeing Tours, since 1995, has had eight accidents and one "incident," after which the NTSB made a number of safety recommendations, Hersman said.
"I think the fact that we are here today shows there is a lot of work that still needs to be done," she said.
Saturday's crash was the company's first involving fatalities.
Marcia Horowitz, a spokeswoman for the tour operator, said Liberty executives were working with investigators.
"The company is focusing its efforts on cooperating with the NTSB and giving as much information as it can," Horowitz said. "At this time, their priority is to help with the family of their pilot and, of course, the families that were involved in the accident."
