Wind Caused Plane To Drift In Turn

The National Transportation Safety Board on Friday released the following update on its investigation into the accident involving a Cirrus Design SR20, N929CD, that crashed into an apartment building while maneuvering above Manhattan, NY on October 11, 2006.

The accident occurred about 2:42 pm eastern daylight time. The airplane was destroyed by impact forces and a post crash fire. The certificated private pilot owner of the airplane, New York Yankees pitcher Cory Lidle, and a certified flight instructor were fatally injured. Marginal Visual Flight rules conditions prevailed, and no flight plan was filed for the flight that departed Teterboro Airport (TEB), Teterboro, New Jersey. The personal sightseeing flight was conducted under the provisions of 14 Code of Federal Regulations Part 91. There were 1 severe and 2 minor injuries on the ground. 

The Safety Board go-team was composed of four teams: Airworthiness, Powerplants, Operations, and Witnesses. The Weather, Air Traffic Control and Aircraft Performance group chairmen gathered data from NTSB headquarters. Parties to the investigation are Cirrus Design, Federal Aviation Administration, Teledyne Continental Motors, and Ballistic Recovery System.

The on-scene examination of the wreckage has shown that there was no sign of an in-flight fire or damage to the airplane. The airplane impacted the 30th floor of the apartment building, bounced off, then fell to the street below, where it came to rest inverted and was engulfed in a severe post crash fire. The engine was ejected from the airplane and entered the building through an apartment window on the 30th floor. 

The New York Central Park Automated Observation System reported that at the time of the accident, that the winds were from 060 degrees at 6 knots, visibility at 7 statute miles, ceiling overcast at 1800 feet above ground level, the temperature was 17 degrees Celsius, the dewpoint was 13 degrees Celsius and the altimeter was 29.90 inches of Mercury (Hg).  No visibility restrictions were reported at any of the surrounding airport weather stations. An aircraft that was landing at Newark Liberty International Airport (KEWR) at the time of the accident was equipped with a weather reporting capability that indicated that the winds at 700 feet altitude were from 095 degrees at 13 knots.

Over fifty witnesses to the accident were identified and many interview summaries were obtained from the New York Police Department. Eleven of those witnesses saw the airplane before it impacted the building.

Radar data indicate that the airplane was flying over the east side of Roosevelt Island prior to initiating a 180 degree turn. At this location, there would have been a maximum of 2100 feet clearance from buildings, if the full width of the river had been used. However, from the airplane's mid-river position over Roosevelt Island, the available turning width was only 1700 feet. The prevailing wind from the east would have caused the airplane to drift 400 feet toward the building during the turn, reducing the available turning width to about 1300 feet. At an airspeed of 97 knots, this turn would have required a constant bank angle of 53 degrees and a loading of 1.7 Gs on the airplane. If the initial portion of the turn was not this aggressive, a sufficiently greater bank angle would have been needed as the turn progressed, which would have placed the airplane dangerously close to an aerodynamic stall.

(Note: This "box canyon" theory was also put forth by CFI Tom Turner in an ANN Special Feature recorded October 12, one day after the accident -- Ed.)

Since the accident, The FAA issued a Notice to Airman prohibiting fixed wing aircraft such as the accident flight from operating in the East River Class B Exclusion area where the accident occurred unless authorized and controlled by ATC. This will prevent pilots from encountering a situation in which they must attempt a complete u-turn in order to avoid entry into controlled airspace. 

Maintenance records for the accident airplane indicated that all Airworthiness Directives and Service Bulletins had been complied with. The propeller and engine have been examined by Safety Board investigators at their respective manufacturers and they indicated that they were operating normally.

Additional work continues in the investigation. Two damaged portable GPS units were recovered from the wreckage and sent to the manufacturer to try to recover additional data. The memory chip associated with the airplane's Multifunctional Display was retrieved and sent to NTSB headquarters to try to recover any stored data. A damaged laptop computer that was found in the wreckage and may contain flight log information, is being examined at NTSB headquarters. Several cockpit instruments are being examined in the Safety Board laboratories, and work is underway to enhance a video obtained from the Coast Guard that shows the airplane's impact with the building. 

FMI: www.ntsb.gov