WEST LAURENS, NY, USA
N1273G
Cessna T310Q
The pilot purchased a turbocharged twin engine airplane, took it up for an acceptance flight, and the following day departed for home. According to ATC transcripts, about 2 hours into the flight to home, at 21,000 feet, the pilot was suffering from symptoms similar to hypoxia. He was not consistent in maintaining altitude, and failed to acknowledge all radio calls. About 3 hours, 50 minutes into the flight, while descending, the engines started to surge and subsequently lost power. The pilot landed in an open field. Examination of the airplane revealed the fuel tanks were empty except for unusable fuel. The pilot and a witness reported the airplane departed with full tanks. The pilot also reported he checked the oxygen system on both the acceptance flight and accident flight, and it was full. A check of the pilot's flight planning revealed sufficient fuel was available for the planned flight if the engine fuel mixtures were properly leaned. According to the AIM, hypoxia can impair judgement, memory, alertness, coordination and the ability to make calculations.
On June 3, 1999, at 1745 eastern daylight time, a Cessna T310Q, N1273G, was destroyed during a forced landing in West Laurens, New York. The certificated private pilot was seriously injured. Visual meteorological conditions prevailed for the positioning flight which originated from Waterloo Municipal Airport (ALO), Waterloo, Iowa, at 1349. The flight was operated on an instrument flight rules (IFR) flight plan under 14 CFR part 91. The pilot had purchased the airplane and was returning it to his home airport in Mansfield, Massachusetts. He received a weather briefing and filed an IFR flight plan. He requested FL 210 (21,000 feet) as his en route altitude. The flight departed at 1349, and the pilot reported level at FL 210 at 1439. At 1539, the controller advised the pilot that he was 300 feet low, and the pilot acknowledged the report. Between 1539 and 1947, there were multiple radio calls to the pilot that his altitude readout was low. At 1601, the pilot was asked if was on oxygen and he acknowledged he was. At 1607, the controlled asked the pilot if he wanted a lower altitude, and the pilot thanked the controller for his help. The pilot also reported he had been hand flying the airplane for the last hour and half with no auto-pilot, one communications radio, and one navigation radio. At 1644, the Toronto controller advised the Buffalo controller that N1273G was flying erratically. At 1653, the Buffalo controller called Cleveland Center, Rochester sector, and advised them that N1273G was flying erratically and wasn't talking to anyone. At 1713, the Buffalo controller advised the Toronto controller that N1273G was descending. At 1719, the Buffalo controller advised the Toronto controller that N1273G was changing altitude without a clearance. At 1731, the Boston controller reported that transmissions from N1273G were unintelligible. At 1732, the pilot of N1273G requested a heading to Mansfield, and a lower altitude. The flight was subsequently cleared for a descent, first to FL 190, then 17,000 feet, followed by 11,000 feet. At 1739, the pilot of N1273G requested to land at the nearest available airport. He was advised that Oneonta Airport was 12 o'clock, at 12 miles. The pilot then advised that he was having difficulty with his left engine and again requested to go to the nearest available airport. At 1743, radio and radar contact was lost with the airplane. According to inspectors from the Federal Aviation Administration (FAA), the airplane impacted in an open hay field, and three distinct ground impact marks were found in line to the airplane. They were located 162 feet, 90 feet, and 57 feet from the airplane. They talked to one witness who heard the engines surging. Both wings and the fuselage were wrinkled. There was no smell of gasoline at the accident site. The right tip tank was off the airplane and there was evidence of a small gasoline spill estimated to be about 1 quart. Examination of the left tip tank and both auxiliary wing tanks revealed no fuel present. When a FAA Inspector applied power to the airplane, he observed that the left main tank fuel gage indicated 10 pounds of fuel remaining, and the right main tank fuel gage indicated 30 pounds of fuel remaining. The pilot was taken to a hospital and was unable to be interviewed. Subsequently, in the NTSB Form 6120.1/2, the pilot reported: "...At 21,000 feet, shortly after Dubuque VOR, the auto pilot shut off and I couldn't process how to locate and reset necessary switches to reactivate. In retrospect, this was my initial indication that I was 'impaired'. I continued flight on J94...In retrospect thinking back to the flight I lost all track of time and can only recall bits and pieces of various situation. I found myself misplacing items (chart, pens sun glasses) required in flight. At one point I removed my shoulder harness to retrieve items on the floor. The right engine alternator light was on, and again I was unable to execute resetting the circuit breaker, obviously due to confusion, since I readily knew where it was located. Air traffic control dictated frequency changes and I was mixing up the numbers, leading to my requesting them to repeat. I noticed I would transmit but they couldn't hear me at times they were 'breaking up' as well. I can not recall at what point in flight this was occurring, since I lost all perception of time...next there was a change in the engine sound (surging). I recall switching both tanks back to the mains as I could not discern which engine was surging. This is the point where I lost my conviction about effectively controlling the systems in the airplane. I therefore requested assistance in getting to the nearest airport. I had no real awareness of my location, but knew I needed to get the aircraft down immediately...I executed the controllers instructions as best I could. My remaining focus was concentrated on controlling the airspeed and keeping the wings level to assure a safe landing...When I descended through a broken ceiling at about 1,000 feet, I know I had to get the aircraft down quickly as my thought processing was diminishing. Luckily I was in farm country and spotted a field in which could safely set down the aircraft without any threat of injuring anyone. I successfully brought the plane down 'gear up'...." The pilot had one previous flight in the airplane, an acceptance flight prior to purchase. A check of the Turbo-System Cessna 310Q owner's manual, revealed the airplane would climb to 20,000 feet in 20 minutes, and burn 100 pounds of fuel during the climb. The remaining 878 pounds of fuel would give the airplane an at altitude endurance of 5.37 hours at 2,350 RPM, and 25 inches of manifold pressure. According to the pilot, the planned flight time was 5 hours. A witness reported, "...The aircraft fuel tanks (4) were topped (6-2-99, 82.2 gal) and verified per my visual inspection...." In addition, the pilot reported that he departed with 163 gallons onboard. The airplane was equipped with a 76.6 cubic foot, constant flow oxygen system. According to the pilot, the system was full when he departed, and he had checked that the system was operational on the acceptance flight made the day before the accident. According to the duration chart in the owner's manual, a full tank (1,800 PSI) would be supply oxygen to one pilot for over 10 hours at 22,000 feet. The system is turned on by pulling a knob to the extended position, and turned off, buy returning the knob to the retracted position. The owner's manual contains the following note: "If the oxygen knob is left in an intermediate position between ON and OFF, it may allow low pressure oxygen to bleed through the regulator into the nose compartment of the aircraft." The FAA inspector reported that when he checked the oxygen system a few days after the accident, the system was empty. In a follow-up telephone interview, the pilot reported he had limited memory of the flight. He did remember checking the oxygen system on the acceptance flight and it was full. He said he checked it again on the accident flight and it was about one needle width off of full. According to the Aeronautical Information Manual (AIM), Section 8-1-2 Effects of Altitude: "...Hypoxia is a state of oxygen deficiency in the body sufficient to impair functions of the brain and other organs...judgement, memory, alertness, coordination and ability to make calculations are impaired, and headache, drowsiness, dizziness and either a sense of well-being (euphoria) or belligerence occur...The altitude at which significant effects of hypoxia occur can be lowered by a number of factors...certain medications can reduce the oxygen-carrying capacity of the blood to the degree that the amount of oxygen provided to body tissues will already be equivalent to the oxygen provided to the tissues when exposed to a cabin pressure altitude of several thousand feet...low doses of certain drugs, such as antihistamines, tranquilizers, sedatives and analgesics can through their depressant action, render the brain much more susceptible to hypoxia. Extreme heat and cold, fever, and anxiety increase the body's demand for oxygen, and hence its susceptibility to hypoxia...."
the pilot's impairment due to hypoxia, which resulted in reduced situational awareness and a power loss due to fuel exhaustion.
Source: NTSB Aviation Accident Database
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