New York (CNSNews.com) - Investigators tracing the activities of the terrorists who crashed jetliners into the World Trade Center are examining the possibility that they may have rented small airplanes to perform "fly-bys" of the twin towers.
The hijackers, who earned their pilot's licenses in the United States, may have rented small planes at one or more New Jersey airports in the two months prior to September 11th.
Investigators are pursuing leads that the hijackers performed "dry runs," but FBI Special Agent Sandra Carroll said investigators cannot confirm or deny "the fact that they could have rented planes and rehearsed."
"There are 15 airports in the area, and the FBI has been to every one of them," according to a representative of the Caldwell Flight School who asked not to be identified.
Caldwell Flight School is located at Caldwell Airport in Fairfield, New Jersey. It is one of the larger commuter airfields in the state and is located less than 30 miles from Manhattan -- a 15- to 20-minute flight to the Hudson River.
Since some of the hijackers had pilot's licenses, it would not have been difficult for them to rent a plane to survey the area. Flight schools and companies that rent planes usually charge between $55 and $70 an hour for the rental of a single-engine plane, such as a Cessna, which can seat two to four people. It costs up to $250 an hour to rent a larger, twin-engine plane.
Before Sept. 11, the FAA did not require pilots of small planes to file a flight plan for most flights over New Jersey.
There are small commuter airports all over New Jersey. The airspace that a small single-engine plane would fly was traditionally considered "Class C," or "unrestricted," meaning pilots would not have to gain permission from an air traffic controller (ATC).
The airspace around Newark International Airport is restricted, meaning the only way to gain access is through the ATC, and so is the area above the World Trade Center. However, until now, the airspace over the Hudson River was not controlled under 1,000 feet.
Both of the commercial jetliners that crashed into the twin towers used approaches that took them low over the Hudson River, and they would have been flying at or below 1,000 feet upon impact.
Having knowledge of the airspace would have helped the hijackers to pinpoint their precise locations and allowed them to guide their planes visually to where they wanted to go.
"There's no way someone could fly as low as they did and not know the airspace. They had to have flown around before to have their bearings," said Danny Montes, a certified helicopter flight instructor and a former radio station pilot.
Montes has spent well over a decade in the skies of New York City and is one of the most experienced helicopter pilots in the area. Montes also remembered an event that took place about one month prior to the attack on the World Trade Center.
"I was flying one day when I heard an Arabic-sounding voice on 123.00 (the radio frequency used by pilots in uncontrolled airspace in the New York/New Jersey area which includes the Hudson River). I was surprised because I never heard anyone on the open (123.00) before that sounded like they were from the Middle East," said Montes. "And, I haven't heard another voice like that since."
"I believe they flew that day from the west (western New Jersey) because they stayed on 123.00 when they left the Hudson River," said Montes.
Before the terrorist attacks and the new FAA flight restrictions were implemented, anyone with a pilot's license could fly under 1,000 feet without having to relay their position to an airport control tower. "They could have flown from Caldwell or most airports in the area to the Hudson River without filing a flight plan or talking to an ATC," said the representative of Caldwell Flight School.
And according to Montes, "All they needed to do is fly VFR (visual flight rules) at or below 1,000 feet."
While the "reconnaissance" information would have helped the hijackers, so did the weather.
"The weather could not have been better" on Sept. 11, said Montes, who was scheduled to be flying that morning. "The visibility was better then 50 miles, and there was hardly a cloud in the sky. They could have easily seen the twin towers from the Catskills (in upstate New York)."
New Jersey continues to be a focus of the terrorism investigation. At least six of the 19 suspected hijackers either lived in or visited New Jersey within months of the World Trade Center attacks.
It is believed three of those who had pilot's licenses lived in New Jersey.
Since the terrorist attacks, the FAA has imposed a strict ban on both commercial and noncommercial flights. A pilot now must give the FAA a complete flight plan and stick to it. No deviations from the flight plan are allowed.
Pilots are warned that failure to adhere to the flight rules can result in military intervention. The armed forces have been given the order to force or shoot down any unauthorized aircraft in US airspace.
(Editor's note: CNSNEws.com Correspondent Jeff McKay is a former airborne reporter who reported traffic and news from the skies over New York City.)