New York

The Boeing 767 departed Boston-Logan at 0759LT on a regular schedule service to Los Angeles, carrying 81 passengers and a crew of 11. Few minutes later, the aircraft was hijacked by terrorists who modified the flight path and flew direct over New York. At 0845LT, the aircraft struck the North Tower of the World Trade Center, between 94th and 99th floor. The aircraft disintegrated on impact and all 92 occupants were killed. The tower later collapsed. The terrorist attacks of September 11, 2001 are under the jurisdiction of the Federal Bureau of Investigation. The Safety Board provided requested technical assistance to the FBI, and this material generated by the NTSB is under the control of the FBI. The Safety Board does not plan to issue a report or open a public docket.

While departing from the airport, with the second-in-command (SIC) at the controls, the airplane impacted a fence, and subsequently the ground about 1,000 feet beyond the departure end of the runway. A witness on the ramp area south of the runway, stated that he heard the engines spool up; however, due to the fog, he could only see the strobe lights on the airplane. He then observed the airplane rotate about 3,500 feet from the departure end of the runway and begin to climb at a steep angle, before losing sight of it when it was about 150 feet above ground level. The weather reported, at 0550 was, calm winds; 1/2 statute miles of visibility, fog; overcast cloud layer at 100 feet; temperature and dew point of 17 degrees Celsius. Excerpts of the cockpit voice recorder (CVR) transcript revealed that the flightcrew discussed the prevailing visibility at the airport on numerous occasions, and indicated that it appeared to be less than one mile. Examination of the wreckage revealed no anomalies with the airframe or engines. According to the FAA Instrument Flying Handbook, "Flying in instrument meteorological conditions (IMC) can result in sensations that are misleading to the body's sensory system...A rapid acceleration, such as experienced during takeoff, stimulates the otolith organs in the same way as tilting the head backwards. This action creates the somatogravic illusion of being in a nose-up attitude, especially in situations without good visual references. The disoriented pilot may push the aircraft into a nose-low or dive attitude."

After about a 20 minute flight, while on final approach for landing, the airplane experienced a loss of engine power on both engines, and the pilot-in-command (PIC) performed a forced landing into trees about 1/2 mile from the airport. The left and right boost pumps and the left and right transfer pumps, were observed in the "OFF" position. According to the PIC, after he exited the airplane, he returned to the cockpit and "shut off the fuel panel. The fuel quantity indicator toggle switch was observed in the "TOTAL" position. Examination of the fuel system revealed both engine nacelle tanks, both wing center section tanks, and the right wing fuel tanks were not compromised. About 1 quart of fuel was drained from the left and right engine nacelle tanks, respectively. Less than a quart of fuel was drained from the right wing tanks. The left wing tanks were compromised during the accident; however there was and no evidence of a fuel spill. Examination of the left and right wing center tanks revealed approximately 27 gallons (approximately 181 lbs) of fuel present in each tank. Battery power was connected to the airplane, and when the fuel transfer pump switches were turned to the "ON" position, fuel was observed being pumped from the left and right wing center tanks to their respective nacelle tanks. The accident flight was the third flight of the day for the flight crew and airplane. According to a flight log located in the cockpit, the flight crew indicated 750 lbs of fuel remained at the time of the takeoff. According to the airplane flight manual (AFM),"Fuel for each engine is supplied from a nacelle tank and four interconnected wing tanks...The outboard wing tanks supply the center section wing tank by gravity flow. The nacelle tank draws its fuel supply from the center section tank. Since the center section tank is lower than the other wing tanks and the nacelle tank, the fuel is transferred to the nacelle tank by the fuel transfer pump in the low spot of the center section tank...." Additionally, with the transfer pumps inoperative, all wing fuel except 28 gallons from each wing will transfer to the nacelle tank through gravity feed.

The pilot said the preflight, engine start, run-up, taxi and takeoff were "normal". The pilot said that during the climb after takeoff, approximately 1,000 to 1,500 feet above the ground, the airplane's engine "spooled down, slowly and smoothly, like a loss of torque or the propeller going to feather." The pilot performed a forced landing to a field, where the airplane nosed over, and came to rest inverted. Examination of the engine and propeller revealed that the propeller-reversing lever was installed on the wrong side of the reversing lever guide pin, and that the reversing linkage carbon block was no longer installed, and had departed the airplane. Examination of the airplane's maintenance records revealed that the carbon block was replaced during a 100-hour maintenance inspection, 5 hours prior to the accident. Installation of the reversing lever on the incorrect side of the guide pin resulted in improper seating and premature wear of the carbon block. According to the engine manufacturer, any disconnection in operation of the propeller control linkage will cause the propeller governor beta control valve to extend, and drive the propeller into feather.

The captain stated that prior to departure the flight controls were tested, with no abnormalities noted, and the takeoff trim was set to the "middle of the takeoff range," without referring to any available pitch trim charts. During the takeoff roll, the pilot attempted to rotate the airplane twice, and then aborted the takeoff halfway down the 4,840 foot long runway, because the controls "didn't feel right." The airplane traveled off the departure end of the runway and through a fence, and came to rest near a road. The pilot reported no particular malfunction with the airplane. Examination of the airplane revealed that the horizontal stabilizer was positioned at -4.6 degrees, the maximum nose down limit within the takeoff range. The horizontal stabilizer trim and elevator controls were checked, and moved freely through their full ranges of travel. According to the AFM TAKEOFF TRIM C.G. FUNCTION chart, a horizontal stabilizer trim setting of -7.2 was appropriate with the calculated C.G. of 20% MAC. Additionally, Learjet certification testing data stated that the pull force required at a trim setting of -6.0 degrees, the "middle of the takeoff range", was 33 pounds. With the trim set at the full nose down position (-1.7 degrees), 132 pounds of force was required.

While in cruise flight, at 6,000 feet, the left engine lost power. The pilot attempted a restart of the engine, but only about one-half rotation of the left engine propeller was observed, and the engine was secured. The pilot stated that he was unable to maintain altitude and initiated a decent. He requested and was cleared for an instrument approach at an airport where the weather conditions were, 1/4 statute mile of visibility, fog, and a vertical visibility of 100 feet. On the approach, at the minimum descent altitude, the pilot executed a missed approach. As the airplane climbed, the pilot reported to the controller that the 'best altitude [he] could get was 2,200 feet.' A second approach was initiated to the reciprocal runway. While on the second approach, the pilot 'was going to fly the aircraft right to the runway, and told the controller so.' He put the gear down, reduced power, and decided there was 'no hope for a go-around.' He then 'flew down past the decision height,' and about 70-80 feet above the ground, 'added a little power to smooth the landing.' The pilot also stated, 'The last thing I remember was the aircraft nose contacting the runway.' A passenger stated that once the pilot could not see the runway, [the pilot] 'applied power, pitched the nose up,' and attempted a 'go-around' similar to the one that was executed on the first approach. Disassembly of the left engine revealed that the crankshaft was fatigue fractured between connecting rod journal number 2 and main journal number 2. Review of the pilot's operating handbook revealed that the single engine service ceiling, at a weight of 4,800 pounds, was 11,700 feet. The average single engine rate of climb, at a pressure altitude of 6,000 feet, was 295 feet per minute. The average single engine rate of climb, at a pressure altitude of 1,625 feet, was 314 feet per minute. Review of the ILS approach plate for Runway 34 revealed that the decision height was 200 feet above the ground.

The airplane was on an IFR flight plan, level at 16,000 feet, when radar and radio contact was lost. The tops of the clouds in the area of the accident were reported to be at 18,000 feet. A pilot who was flying in the area of the accident site at the time of the accident stated that the cloud tops of 'the buildups' were from 16,000 to 20,000 feet. The pilot additionally stated that moderate unexpected turbulence was encountered and 'Obviously, the updrafts in the area were very strong.' Satellite imagery data revealed that an east-west cloud band, about 10 miles wide, was located in the area of the accident. The ground track of the airplane was traversing the cloud band during the minutes prior to and around the accident time. The onboard weather radar was found in the off position. According to Advisory Circular -00-6A, 'Do avoid by at least 20 miles any thunderstorm identified as severe or giving an intense radar echo. Do clear the top of a known or suspected severe thunderstorm by at least 1,000 feet altitude for each 10 knots of wind speed at the cloud top.' The airplanes calibrated airspeed (KCAS) was calculated at 141 knots, and the indicated airspeed (KIAS) was 139 knots. According to the POH, the maneuvering speed at gross weight was 135 KCAS and 133 KIAS.

Shortly after takeoff, the No. 2 engine failed and shutdown procedures for the No. 2 engine were accomplished. The flight crew declared an emergency and requested to return to the airport. On approach, an engine out go-around was required as ATC had instructed the flight crew of a B-747 to "position and hold" on the end of the runway. The first officer was the pilot flying. Following an uneventful touchdown, as the airplane slowed to about 80 knots, the captain took control of the airplane. Shortly thereafter, the right main landing gear (MLG) collapsed and the airplane slid to a stop on the runway. Examination of the No. 2 engine revealed that 80 percent of the main fuel pump main drive shaft was worn to the spline root. The examination also revealed that the grease used to lubricate the main drive shaft output splines was not the authorized grease specified per OHM 73-11-1 or MIL-G-81322. Additionally, the magnetic seal compression O-ring that rides on the drive gear journal outer diameter was hardened and exhibited inner diameter axial cracks. The component manufacturer indicated that the failure of the magnetic seal was the first such reported incident in 30 years; however, it agreed to review operational data from airlines to reevaluate the mean time between overhaul intervals for the seal and to recommend an inspection interval, as necessary. Examination of the right MLG revealed a fracture failure of the trunnion bearing support fitting that was caused by fatigue cracking and stress corrosion cracking.

On approach to White Plains-Westchester County Airport, the crew noted a left main gear unsafe light. The gear was recycled and the crew agreed with ATC to perform a low pass to check the gear. Few minutes later, upon landing, the left main gear collapsed. All four occupants escaped uninjured while the aircraft was damaged beyond repair.

All positions at LaGuardia Tower were combined to the local control position from 0011 EST until after the accident. At about 0430 EST, ground personnel in 'Vehicle 1277' (communicating on ground control frequency), were cleared on runway 13/31 to perform 'lighting maintenance.' Later, during repair of centerline lights and while N117FJ was inbound to the airport, Vehicle 1277 stalled on runway 13/31. Personnel of Vehicle 1277 attempted to restart the vehicle, but were unable, so they shut off all vehicle lights to reduce electrical load, and again attempted to restart the vehicle, but to no avail. At 0507 (during darkness), N117FJ made initial call to the tower for landing. The controller acknowledged the call, scanned runway 13/31, did not see Vehicle 1277, and cleared N117FJ to land on runway 31. At 0510, personnel of Vehicle 1277 observed N117FJ in the approach/landing phase and radioed ground controller that they were stuck on the runway. The controller then radioed, 'go-around, aircraft on the runway go-around, aircraft on the runway go-around, seven fox juliet go-around.' Moments later, N117FJ impacted Vehicle 1277. The FAA ATC Handbook stated, 'Ensure that the runway to be used is clear of all known ground vehicles, equipment, and personnel before a departing aircraft starts takeoff or a landing aircraft crosses the runway threshold.'