CEN14FA522

The pilot’s failure to recognize the airplane’s low altitude and arrest the airplane’s descent on approach to the airport in dark night conditions, which resulted in controlled flight into terrain. Contributing to the accident was the pilot’s degraded night vision due to glaucoma and a cataract and his impairment from the use of diphenhydramine.

The private pilot was approaching the destination airport at the conclusion of a cross-country flight in dark night, visual meteorological conditions. According to radar track data, the pilot had maintained a gradual descent profile during the final 7 minutes of the flight. About a minute before the accident, during a routine conversation, the tower controller at the destination airport told the pilot that he saw the airplane on radar at 1,800 ft mean sea level (msl). At that time, the airplane was about 1,200 ft above the ground and descending. The airplane subsequently collided with trees located along a ridge at an elevation of about 645 ft msl. The destination airport was located at 712 ft msl. According to radar track and engine monitoring data, the pilot did not attempt to slow the airplane's descent before the accident. A postaccident examination of the airplane and flight instruments did not reveal any anomalies that would have precluded normal operation during the accident flight. Additionally, the pilot had selected a Kollsman window setting that would have minimized any altimeter indication errors. The 80-year-old pilot had moderate-to-severe coronary artery disease, which can result in a sudden loss of consciousness; however, based on available radar track data and his communications with the airport tower controller, it is unlikely that his coronary artery disease contributed to the accident. The pilot also had longstanding, open-angle glaucoma, which had required a series of medical and surgical treatments over the years, and cataracts in both eyes. The cataract in the left eye had been removed in 2008, but the cataract in the right eye had recently increased in size. An ophthalmology evaluation in the weeks before the accident noted a significant increase in the size of a central scotoma (blind spot) related to longstanding glaucoma in the left eye, and declining corrected distant visual acuity bilaterally. Although the pilot met the Federal Aviation Administration medical certification standard of 20/40 vision in daylight conditions, the glaucoma and cataract likely impaired his night vision and, as such, impeded his ability to judge altitude using available visual cues in dark nighttime conditions. Additionally, toxicology testing identified diphenhydramine, a sedating antihistamine, in the pilot's blood at therapeutic levels. Research has shown that the use of diphenhydramine can impair cognitive and psychomotor performance. The pilot's failure to identify the airplane's low altitude during cruise descent further supports that he was likely impaired by the use of diphenhydramine.

A review of available air traffic control (ATC) information indicated that the accident flight had received normal services and handling. A summary of the voice communications recorded between the accident pilot and the Aurora tower controller is included with the docket materials associated with the investigation. The Aurora Municipal Airport (ARR), located about 1 mile northwest of Sugar Grove, Illinois, was served by three runways: 9/27 (6,501 ft by 100 ft, concrete); 15/33 (5,503 ft by 100 ft, concrete); and 18/36 (3,198 ft by 75 ft, asphalt). The airport elevation was 712 ft mean sea level msl. The airplane's Insight Avionics GEMINI 1200 graphic engine monitor, s/n 1535, was downloaded at the National Transportation Safety Board (NTSB) Vehicle Recorders Laboratory in Washington D.C. The accident flight included 806 lines of data for both engines. The engine parameter data was recorded once every six seconds. The engine monitor recorded exhaust gas temperature, cylinder head temperature, and turbine inlet temperature. A review of the recovered engine parameter data revealed consistent readings throughout the accident flight and no anomalies with engine operation. The data stopped recording abruptly after 1 hour 20 minutes 30 seconds, consistent with a loss of electrical power during the impact sequence. The Shadin electronic fuel flow indicator, s/n 8430, was examined at the NTSB Vehicle Recorders Laboratory. All fuel readings were based on fuel flow to the engine. The fuel flow indicator contained non-volatile memory for fuel remaining and the amount of fuel used since the device was last reset. The device was powered-up and indicated that 55.9 gallons of fuel had been used and that there was 67 gallons of fuel remaining. According to the FAA Airplane Flying Handbook (FAA-H-8083-3B), "Night flying is very different from day flying and demands more attention of the pilot. The most noticeable difference is the limited availability of outside visual references. Therefore, flight instruments should be used to a greater degree in controlling the airplane." The handbook further states, "Distance may be deceptive at night due to limited lighting conditions. A lack of intervening references on the ground and the inability to compare the size and location of different ground objects cause this. This also applies to the estimation of altitude and speed. Consequently, more dependence must be placed on flight instruments, particularly the altimeter and the airspeed indicator." On September 30, 2014, the Kendall County Coroner Office, located in Yorkville, Illinois, performed an autopsy on the pilot. The cause of death was attributed to multiple blunt-force injuries sustained during the accident. The autopsy also indicated that caffeine and diphenhydramine (.076 ug/ml) were identified in cavity blood. The FAA's Civil Aerospace Medical Institute located in Oklahoma City, Oklahoma, performed toxicology tests on samples obtained during the autopsy. The toxicological test results were negative for carbon monoxide and ethanol. The testing identified atenolol and diphenhydramine in urine and cavity blood, and salicylate in urine. The test results indicated 0.136 ug/ml of diphenhydramine was identified in blood. Cavity blood levels may vary widely from dilution by other fluids or because of post mortem redistribution where drug may leech out from storage sites (like liver) into adjacent pooled blood. Diphenhydramine is a sedating antihistamine used to treat allergy symptoms and as a sleep aid. Blood levels between 0.0250 and 0.1120 ug/ml are considered therapeutic. Diphenhydramine carries the following Food and Drug Administration warning: May impair mental and/or physical ability required for the performance of potentially hazardous tasks (e.g., driving, operating heavy machinery). Compared to other antihistamines, diphenhydramine also causes marked sedation, and as a central nervous system depressant, is often used a sleep aid. Altered mood and impaired cognitive and psychomotor performance may also be observed in conjunction with the use of diphenhydramine. Atenolol is prescription medication that lowers blood pressure and decreases the likelihood of a recurrent heart attack. Salicylate is a metabolite of aspirin, which is commonly used by patients with coronary artery disease to prevent a heart attack. The 80-year-old pilot had a history of coronary artery disease that required angioplasty and stenting of the left anterior descending artery in 2007, along with hypertension. He was on a number of medications to control his blood pressure and limit the progression of his coronary artery disease. However, the autopsy identified moderate to severe new stenosis in the portion of the left anterior descending coronary artery distal to the stent, and evidence of hypertensive cardiovascular disease in his heart and kidneys. In addition, the pilot had longstanding open angle glaucoma (since 1985) which had required a series of medical and surgical treatment over the years, and cataracts in both eyes. The cataract in the left eye had been removed in 2008 but the one in the right eye was increasing in size before the accident. An ophthalmology evaluation in the weeks before the accident noted a significant increase in the size of a central scotoma (blind spot) related to longstanding glaucoma in the left eye and declining corrected distant visual acuity bilaterally, although the pilot met the FAA standard of 20/40 vision. The airplane collided with several 30-foot tall trees located along a ridgeline at 645 ft msl. All airframe structural components and flight control surfaces were located along the wreckage debris path. Both wings and tailbooms separated from the fuselage during the collision with the trees. The right wing had a large semicircular crush region, located about midspan, which was consistent with the average tree diameter near the initial point of impact. The fuselage was located 475 ft northeast of the ridgeline in a cornfield. All observed structural component failures were consistent with overstress separation and there was no evidence of an inflight or postimpact fire. Flight control continuity could not be established due to the extent of the damage; however, all observed flight control system discontinuities were consistent with overstress. The elevator trim position could not be determined due to impact damage. The wing flaps were fully retracted. The nose and main landing gear were fully retracted. The fuel control valves and their control lever positions were compromised during the impact sequence. Both electric fuel pump switches were in the OFF position. The altimeter's Kollsman window was centered on 30.06 inches of mercury. The altimeter sustained impact-related damage during the accident and could not be bench tested. The postaccident airframe examination revealed no evidence of a preimpact mechanical malfunction or failure that would have precluded normal operation. The front engine separated from the fuselage and was located about 90 ft northeast of the main wreckage. The engine sustained significant impact-related damage that resulted in the fracture of the crankcase, crankshaft, and the No. 5 cylinder head, as well as the separation of the turbocharger, fuel pump, and both magnetos. One of the magnetos and the mechanical fuel pump were not located during the on-scene investigation. The impact damage sustained during the accident precluded a functional test of the engine. The crankshaft fractured in an area that coincided with the No. 4 main bearing oil galley. The crankshaft fracture displayed 45-degree shear lips and a cupped appearance. Crankshaft continuity was confirmed from the aft end of the engine to the crankshaft fracture area and to each of the connecting rods. Camshaft continuity was confirmed from the aft end of the engine, to the bevel gear. A borescope inspection revealed no preimpact anomalies with the cyli