The December 2011 crash claimed the lives of pilot Jeffrey Buckalew, an investment banker; his wife and two children, and Rakesh Chawla, a colleague at New York's Greenhill & Co. Buckalew was the registered owner of the single-engine Socata TBM 700 and had more than 1,400 hours of flight time, according to the report.
The plane had just departed Teterboro Airport en route to Georgia when it began spiraling out of control at about 17,000 feet and crashed on a wooded median on Interstate 287 near Morristown. No one on the ground was injured. Wreckage was scattered over a half-mile area, forcing the closure of the busy roadway for several hours.
The National Transportation Safety Board report concluded that while Buckalew had asked air traffic controllers to fly higher and out of the icing conditions, he may have been reluctant to exercise his own authority to do so, or may have been unaware of the severity of the conditions.
The NTSB attributed the cause of the accident to "the airplane's encounter with unforecasted severe icing conditions that were characterized by high ice accretion rates and the pilot's failure to use his command authority to depart the icing conditions in an expeditious manner, which resulted in a loss of airplane control."
According to the report, an air traffic controller advised Buckalew of moderate icing from 15,000 to 17,000 feet, at which point Buckalew responded, "we'll let you know what happens when we get in there and if we could go straight through, it's no problem for us." The controller then directed him to climb to 17,000 feet.
When the plane reached 16,800 feet Buckalew reported light icing and said "a higher altitude would be great." Seventeen seconds later, he said the plane was experiencing "a little rattle" and asked to be cleared to go to a higher altitude "as soon as possible please."
The controller coordinated with a controller in an adjacent sector and, 25 seconds later, directed Buckalew to climb higher. Within about a minute the plane had reached 17,800 feet and then began an uncontrolled descent.
Ice can form on airplanes when temperatures are near freezing and there is visible moisture, such as clouds or rain. The ice adds weight to an aircraft, and rough accumulations known as rime interrupt the flow of air over wings.
Numerous pilots had reported icing conditions in the area around the time of the accident, including at least three flight crews that characterized the icing as severe, according to the report. One pilot told NTSB investigators his wing anti-icing system "couldn't keep up" with ice accumulation of as much as 4 inches that had developed over a span of five minutes.
Pilots are required to fly under the direction of air traffic controllers but federal regulations allow for some deviation in emergency situations. The NTSB report quotes a part of the Federal Aviation Regulations that reads, "in an in-flight emergency requiring immediate action, the pilot in command may deviate from any rule of this part to the extent required to meet that emergency."