Bart Jansen and David Andreatta

A plane belonging to a prominent New York real estate developer and his wife crashed in the ocean north of Jamaica after flying unresponsive for hours and being escorted by U.S. fighter jets, according to federal officials.

The U.S. Coast Guard is searching for the wreckage, as are a Jamaican military helicopter and search-and-rescue team. Jamaica rescuers said they have located an oil slick in waters where they suspect the plane went down.

The single-engine turbo-prop is registered to Rochester developer Larry Glazer.

"We understand that there are many questions yet to be answered about today's events, and we too are awaiting answers. At this time, we would appreciate the ability to mourn privately.""We are devastated by the tragic and sudden loss of our parents, Jane and Larry Glazer," the statement read. "They loved and appreciated the opportunity to help build the community of Rochester, and we thank everyone in the community for their expressions of support.In a prepared statement, their children, Mindy, Rick and Ken Glazer, said they were awaiting answers as to what went wrong.

The North American Aerospace Defense Command scrambled two F-16 fighter jets from South Carolina at 10:40 a.m. to intercept the Socata TBM-900 headed from Rochester, N.Y., to Naples, Fla. Those planes handed off the escort to two F-15 fighters from Florida at 11:30 a.m.

Military pilots weren't able to communicate with the plane's occupants, but saw that the plane's windows were frosted, according to Army Maj. Beth Smith, a NORAD spokeswoman.

Authorities have not confirmed who was on the plane. But within minutes of the crash, New York officials offered public condolences to the Glazer family.

FlightAware identified the plane's tail number as N900KN. FAA records show the plane, a model that sells new for $3.5 million in its standard version, is owned by a company based at the same address as a real estate firm in Rochester. The firm, Buckingham Properties, is owned by developer Larry Glazer, who also is president of the TBM Owners and Pilots Association."I join the residents of Rochester during this difficult week in mourning the loss of Larry and Jane Glazer in today's tragic plane crash," said Gov. Andrew Cuomo. "The Glazers were innovative and generous people who were committed to revitalizing downtown Rochester and making the city they loved a better place for all."

According to Buckingham's website, "Larry spends some of his spare time on the ground - gardening around his house with his wife, Jane; and some in the sky - flying his plane."

Joseph Rowley Jr., director of leasing and marketing at Buckingham Properties, which is owned by Glazer, declined to comment. The company closed early Friday.

A woman answering the phone at QCI Direct, a catalog company owned by Glazer's wife, Jane Glazer, at 2:15 p.m., said the company was not making any public statements.

Moments later, a voice recording at QCI said the company was closed.

The plane took off at 8:26 a.m. and was scheduled to land in Naples about noon, according to FlightAware.com, a flight-tracking service. The plane crashed at 2:15 p.m., about 14 miles off the coast of Port Antonio, Jamaica, according to NORAD.

On a recording made by LiveATC, a website that monitors and posts air traffic control audio recordings, the pilot can be heard saying, "We need to descend down to about (18,000 feet). We have an indication that's not correct in the plane." A controller replied, "Stand by."

After a pause, the controller told the pilot to fly at 25,000 feet. "We need to get lower," the pilot responded. "Working on that," the controller said

Controllers then cleared the plane to descend to 20,000 feet, a command which the pilot acknowledged. A couple minutes later, a controller radioed the plane by its tail number: "900 Kilo November, if you hear this transmission, ident" - identify yourself. There was no response.

According to FlightAware, the plane never carried out the last descent to 20,000 feet.

Fighter pilots observed the Socata's pilot slumped over before the turboprop's windows became frosted over, Schlachter said.

On LiveATC recordings, the fighter pilots can be heard discussing the Socata pilot's condition.

"I can see his chest rising and falling right before I left," said one of the fighter pilots.

"It was the first time we could see that he was actually breathing. It may be a deal where, depending on how fast they meet them, he may regain consciousness once the aircraft starts descending for fuel ..." the fighter pilot said.

The pilot was speculating that the Socata pilot was suffering from hypoxia, or oxygen deprivation, but Schlachter said the Air Force doesn't know for certain that was the case.

The incident is the second time in less than a week that private pilot has become unresponsive during a flight. On Saturday, a pilot lost consciousness and his plane drifted into restricted airspace over the nation's capital. Fighter jets were also launched in that case and stayed with the small aircraft until it ran out of fuel and crashed Saturday into the Atlantic.

Cases of pilots becoming unresponsive while their planes wander the sky are unusual, with probably not much more than a handful of such incidents over the last decade, said aviation safety expert John Goglia. Sometimes the incidents are due to a pilot becoming incapacitated by a heart attack or stroke, but more often the problem is insufficient cabin pressurization that causes the pilot and any passengers to pass out, he said.

Pilots are supposed to check that the cabin pressurization is correctly set before takeoff, but there have been cases where they have forgotten to do that or the pressurization level has been improperly set, said Goglia, a former National Transportation Safety Board member. If cabin pressure drops too low, there won't be enough oxygen per cubic foot in the cabin and any people aboard will lose consciousness, he said. In such cases, it's likely that those on board will die from loss of oxygen before the plane runs out of fuel and crashes, he said.

Mechanical problems or a window or fuselage leak can also lead to rapid cabin depressurization. When that happens, the time of useful consciousness a pilot has in which to react is measured in seconds, Goglia said.

In 1999, the pilots of a Learjet carrying professional golfer Payne Stewart from Orlando, Florida, to Texas became unresponsive. The plane took a turn and wandered all the way to South Dakota before running out of fuel and crashing into a field west if Aberdeen. Stewart and five others on board were killed. An NTSB investigation blamed the accident on depressurization.

The military routinely responds to unknown aviation activity, with heightened security after the terrorist attacks on Sept. 11, 2001. But the incidents are often accidents rather than terrorist incidents.

Two F-16 fighter jets followed a general-aviation plane Monday that had taken off from Waukesha Airport in Wisconsin and was on its way to Manassas Airport in Virginia, before it crashed in the Atlantic.

Contributing: Andreatta also reports for the Rochester Democrat and Chronicle, Donna Leinwand Leger.