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On June 08, 2006, about 1530 mountain standard time, a Cessna 152, N627PA, was substantially damaged when it collided with terrain near Peoria, Arizona. Pan Am International Flight Academy was operating the airplane under the provisions of 14 CFR Part 91. The certified flight instructor (CFI), who held a commercial pilot certificate, and the second pilot, who held a commercial pilot certificate, were fatally injured. The CFI was providing dual flight instruction to the second pilot. The local training flight departed from Phoenix Deer Valley Airport, Phoenix, Arizona, about 1445. Visual meteorological conditions prevailed and a flight plan had not been filed.
According to the operator, the flight was scheduled as a spin training lesson. The second pilot was enrolled in the multiengine CFI course, which required spin training as part of the curriculum.
Recorded radar data covering the area of the accident was supplied by the Federal Aviation Administration (FAA) in the form of a National Track Analysis Program (NTAP) printout from the Albuquerque Air Route Traffic Control Center (ABQ ARTCC). The radar data was examined for the accident time frame, and a 1200 beacon code was observed that matched the anticipated flight track of the airplane en route from Deer Valley Airport to the accident area.
The radar data spanned from 1448:40 to 1527:45. The data displayed radar returns that started at Deer Valley Airport and headed in a northwesterly direction, gradually increasing in altitude towards the practice area northeast of the Luke Air Force Base Alert Area A-231. The returns showed a gradual climb of about 380 feet per minute until reaching a mode C reported altitude of 6,100 feet mean sea level (msl) at 1458:06. The target maintained a northerly path around 6,000 feet msl until 1504:11, after which the radar returns reflected a turn to the west.
A review of the remaining data disclosed that the returns made several counterclockwise circular revolutions and zigzags from 1504:21 to 1527:25. During this period the radar returns indicated an oscillation in altitude of approximately 1,000 feet over 1- to 2-minute intervals. In this duration, the returns showed seven similar patterns where there was a short climb followed by a quick loss of altitude. At 1527:25, the target was identified at 5,500 feet msl and the following radar return at 1527:45, which was the last return, revealed an altitude of 3,400 feet msl. The last two radar returns are consistent with a descent from 2,100 feet to 1,250 feet above ground level (agl), in 20 seconds.
According to radar data recorded by the Luke Air Force Base (LUF) terminal radar system, at 1527:24, a visual flight rules (VFR) target (beacon code 1200) was operating in an area located 19-20 nautical miles north of LUF in the vicinity of the Quintero golf course. The track information showed radar returns at 5,600 feet msl, following a course of approximately 045 degrees with ground speed approximately 70 knots. At 1527:29, the track altitude indicated 5,300 feet msl with a of ground speed 70 knots. At 1527:34, the target information and target trails indicated a turn to the east with an altitude of 4,600 feet msl, at 60 knots. Ten seconds later, the radar replay showed that the targets made a hard right turn, rolling out on approximately a 355-degree course. The returns descended to 4,100 feet msl, at approximately 50 knots ground speed. At 1527:49, the returns were tracking approximately 330 degrees, at an altitude of 3,200 feet msl and 40 knots ground speed. The last radar return occurred at 1527:54; it showed an altitude of 2,800 feet msl, with a ground speed of 30 knots.
A review of the records maintained by the FAA disclosed that the instructor held a CFI certificate with airplane ratings for single engine and multiengine land, as well as instrument flight. Her most recent first-class medical certificate was issued on October 26, 2005, and contained no limitations.
A Safety Board investigator reviewed the flight instructor's personal flight logbooks. The two bound books encompassed entries dating from July 08, 2002, to May 12, 2006. According to the logbooks, her total flight experience was 903.3 hours, with 727.4 as pilot-in-command. She had amassed 428.2 hours in the capacity of flight instructing, of which 11 hours was conducted in a Cessna 152. The Cessna flight time was characterized as spin training in the remarks section of the flight log; all of the spin training flights were conducted in the accident airplane.
One of the logbooks indicated that on May 01, 2006, the flight instructor received 1.2 hours of dual instruction in the accident airplane toward a "spin checkout." The other Cessna time showed in the logbooks was listed as "stalls and spins," and conducted in August 2003 (1.3 hours) and January 2004 (1.3 hours). For the later entry there was a corresponding endorsement in the back of the logbook for instructional proficiency in stall awareness and spins (FAR 61.183(i)).
The operator provided a computer printout of the flight instructor's flight time in the Cessna 152 airplane. From May 2006 to the date of the accident, she accrued 32 hours over 23 flights; 14.5 hours were flown in the accident airplane. The flight instructor's last flight was documented by both the operator's electronic records and the airplane's status sheet. On the morning of the accident she conducted a spin training flight that was 1.2 hours.
The second pilot (undergoing instruction) held a commercial pilot certificate with airplane ratings for multiengine land and instrument flight. He additionally held a private pilot certificate with a rating for single engine airplanes. His most recent first-class medical certificate was issued without limitations on June 20, 2005.
According to the operator, the pilot had acquired his total flight experience with their school. At the time of the accident, the pilot was enrolled in a course to receive his CFI certificate.
A review was conducted of the pilot's flight logbooks, which the dates ranged from July 30, 2005, to June 02, 2006. During that time, the logbooks indicated that he had amassed 201.7 hours total flight experience, all of which was conducted in low-wing Piper airplanes and flight simulators. There were no written remarks in his logbook that indicated he had received flight spin training. A flight instructor had however signed his logbook stating that on June 06, 2006, he had given the pilot 1 hour of ground instruction on "spins, spin entries, recovery procedures, stall/spin aerodynamics."
The logbooks disclosed that throughout his flying experience he consistently flew about one to two times per week. An entry was made on April 21, 2006, indicating that he took his commercial checkride, and only three flights were logged thereafter: May 10 and 17, followed by the last entry June 02; these flights totaled 2.8 hours. The operator provided a copy of the pilot's account, which revealed that he additionally flew 1.8 hours during that time (not shown in logbooks). The account paperwork also showed two "no-show" flights during that period. The pilot had originally enrolled in ground school toward the CFI certificate on April 03, 2006, but dropped out after 2 days. He enrolled again on May 01, which he passed with a 93 percent score on May 12.
The airplane was a Cessna 152, serial number 15281078, which was manufactured in 1977. According to the original application for a utility category airworthiness certificate completed by the Cessna factory, a Lycoming O-235-L2C engine was installed at the time of manufacture.
The most recent annual inspection of both the airframe and engine was recorded as completed on February 20, 2006, 76 hours prior to the accident. According to the airplane's maintenance records, the Lycoming O-235-L2C, serial number L-15194-15, was installed on the airframe in November 18, 2004. The logbooks and recording tachometer revealed that, at the time of the accident, it had accumulated a total time in service of 2,746.1 hours and 374.1 hours since the last major overhaul.
A review of the airplane's dispatch sheet revealed that the airplane was last flown on the day of the accident by the accident flight instructor and another student for a total of 1.2 flight hours. The entry before that was dated June 05, 2006, where the airplane was in maintenance to have the battery replaced.
Examination of refueling records at the Deer Valley Airport disclosed that the airplane was last fueled on June 05, 2006, with the addition of 20 gallons of 100LL aviation gasoline.
During the removal of the wreckage, aircraft recovery personnel observed fuel spilling out of both wings.
Weight and Balance
Investigators attempted to reconstruct the airplane's weight and center of gravity (CG) at the time of the accident. The fuel was estimated to be 96 pounds, which accounted for 1.9 hours of fuel burned in the flight prior (1.2 hours) and the initial portion of the accident flight (0.7 hours). The occupant weights were determined from official state identification records as follows: flight instructor, 100 pounds; second pilot, 230 pounds. Using this reconstruction, the gross weight of the airplane at the time of the accident was estimated to be 1,627 pounds with a CG at 32.9 inches. According to the Cessna 152 Pilot's Operating Handbook (POH), the maximum allowable gross weight was 1,670 pounds, and the CG envelope range at 1,627 pounds was from 32.5 to 36.5 inches. A sheet detailing the computations is in the public docket for this report.
A routine aviation weather report (METAR) for Deer Valley Airport was issued at 1453. It stated: skies clear; wind from 200 degrees at 9 knots, gusting to 14 knots; temperature 100 degrees Fahrenheit; dew point 45 degrees Fahrenheit; and altimeter 29.78 inHg.
WRECKAGE AND IMPACT
The wreckage was located at 33 degrees 50.53 minutes north latitude and 112 degrees 25.06 minutes west longitude. The elevation was approximately 2,150 feet msl. All major components of the airplane were accounted for at the scene. The airplane came to rest on the side of a hill (peaking about 220 feet in height).
The first identified point of impact was a crater of disturbed soil located 100 feet from the main wreckage on the southeast side of the hill, just below its peak. According to the FAA inspector who initially responded to the accident, the crater was consistent with an imprint of the fuselage and nose landing gear. A path of wreckage debris was noted extending from the impact crater on a 135-degree magnetic bearing ending at the main wreckage, located on the other side of the hill. The propeller was found in between the initial crater and main wreckage. The engine was displaced from its mounts and came to rest a few feet to the east of the firewall.
Within the wreckage a kneeboard was found with a loose piece of notebook paper secured in its clip. The paper contained several handwritten notations. Shorthand notes of an ATIS (Automated Terminal Information System) report were on the paper, which showed an altimeter setting of 29.81 inHg; the numbers written were consistent with the METAR report given at 1353. The paper additionally had a list written as follows:
MEDICAL AND PATHOLOGICAL INFORMATION
The Maricopa County Office of the Medical Examiner performed autopsies on the flight instructor and second pilot on June 13, 2006.
The FAA Toxicology Accident Research Laboratory, Oklahoma City, Oklahoma, performed toxicological testing on the flight instructor and second pilot. The specimens tested negative for carbon monoxide, cyanide, ethanol and other tested drugs.
TESTS AND RESEARCH
Investigators from the Safety Board, FAA, Cessna Aircraft Company, and Textron Lycoming examined the wreckage on June 15, 2006, at the facilities of Air Transport, Phoenix.
The left wing remained affixed to the fuselage with the aileron and wing flap control surfaces still attached at their respective hinges. The wing sustained aft crush deformation, with the leading edge skin folded into itself giving it an accordianed appearance. The crush began 64 inches inboard, and increased gradually with the greatest crush deformation present in the most outboard portion of the wing, where it measured 8 inches aft. Further crush deformation was found to the left wing's leading edge position on the bottom area of the wing, outboard of the strut. The wing tip was still attached with the navigation light missing.
The right wing was separated from the fuselage. The aileron and flap control surfaces were still attached. The strut was still partially attached. The leading edge displayed crush deformation with the skin folded into itself giving an accordianed appearance from the outboard section to about 59 inches inboard. The wing tip was not attached.
The flap control surfaces were found in the retracted position. The actuator jackscrew was almost flush with the body, revealing no threads. A representative for Cessna Aircraft stated that the position of the jackscrew was consistent to the flaps being in the retracted position. Flap cable continuity was established from the control surface to each wing root.
The aileron surfaces on each wing were attached with a bend in the outboard portion, which was partially separated. Cable continuity was established from the control surfaces to the wing root where the cable was separated and marked as being intentionally severed by personnel who recovered the airplane. Cables were found attached to the control yoke assembly, but investigators were not able to trace them through the cockpit area due to the extensive crush damage in that area. Investigators pulled the cable out of the crush area and did not note any anomalies on the cable exterior. The aileron pullies in that area were compromised.
The rudder control surface remained affixed to the vertical fin structure, but was slightly distorted near the middle hinge area. The tail cone was pushed upwards, resulting in the distorted skin contacting the left rudder horn. Investigators could manipulate the rudder through the full motion of travel with slight difficulty due to binding from the tail cone deformation. The rudder stop bolts were both intact, and remained attached to the distorted skin of the tail cone. The bolts were skewed with the distorted skin and safety wire was present on both. The rudder horn was intact, with the respective rudder bumpers attached. The bumper faces each had shinny areas visible, which the Cessna representative stated was consistent with normal repetitive contact chipping away the painted surface.
The rudder cables were attached to rudder horn, and continuity was established to the forward tail cone through a series of pullies and runs through lightning holes. At the forward tail cone, the airframe was severed for recovery and the rudder cables were cut and marked by the recovery personnel. The left rudder cable was found in the run of the pulley in the aft tailcone and observed going through a hole in the bulkhead assembly station 173.41. The right rudder cable was found within the runs of two pulleys in the aft tailcone and went through a fairlead in the forward tailcone area.
The rudder cables were traced through the fuselage and found to be bound by airframe deformation. Investigators manipulated airframe skin and cut through the fuselage to free the bound cables. The rudder cables were found near their respective pullies and traced to forward pullies where they ran freely to the rudder pedal assembly. The left rudder cable separated aft of the forward pulley in the comprised section of cockpit. That separated cable measured 30 inches from the rudder attachment point to the area where it separated. The remainder of the cable measured 51 inches to the cut in the forward tail cone; with the empennage section of cable measuring 109 inches. The right rudder cable was continuous from the rudder pedal assembly to the forward section of the tailcone, where it was marked as cut by recovery personnel.
The elevator control surface remained attached to the horizontal stabilizer and could be moved freely. Investigators established continuity from the control surface through the pullies located in the tail cone to the cable separation that was a result of recovery. The remaining elevator cables, forward from the separations made from recovery continuing to the forward elevator bellcrank, were bound by the deformed airframe. The pullies were compromised and investigators extracted the cables out of the wreckage, confirming that they were continuous to the forward bellcrank attachments. The forward bellcrank was intact with a portion of push-pull tube still attached. The push-pull tube separated close to bellcrank with a portion lodged in the impact damaged skin. Investigators traced the tube forward, finding that it separated prior to attachment to the control y assembly. There was a portion of the tube still affixed to the base of the control y assembly. Investigators noted that the right elevator cable had a kink prior to the forward bellcrank with a shinny silver coloration exhibited within the kink's cable fibers.
The elevator trim tab remained attached to the elevator. The elevator trim was observed in a slightly down position. The rod actuator measured about 1.31 inches, which the Cessna representative stated corresponded to a 3-degree tab down position. Elevator trim cable continuity was established from the control surface to the forward tailcone area, where it had been cut by recovery personnel. Investigators could not trace the cables through the fuselage area due to the extensive crush deformation. The trim cables were continuous from the control wheel through the forward cockpit area.
Examination of the stall warning system revealed it was operational, and the stall horn produced noise when suction was applied. The pitot/static system was also intact and clear of blockages.
The flap switch was near the 0-degree position. The mixture control was in the full rich position, the throttle control and carburetor heat selector were in the full forward position, and the ignition key was selected to "BOTH."
The tachometer needle was near the 4,000-rpm position with the time indicating 0126.3. The altimeter needle indicated 5,800 feet, and 29.80 was displayed in the Kollsman window. The attitude indicator display was inverted and unreliable. The airspeed indicator needle was affixed at the 78 knots. The face of the turn coordinator was intact, and the ball was deflected left, with the bank showing a vertical 90-degree bank. The vertical speed indicator showed a 250-foot-per-minute decent.
Fuel system continuity could not be established due to the amount of impact damage that the airplane had sustained. No fuel was present in either wing tank. The fuel shutoff valve handle was in the "ON" position. A portion of the forward fuel line, which connects the fuel shutoff valve to the fuel strainer, remained attached to the fuel shutoff body. Upon directing pressurized air into the remaining line, investigators noted that the air traveled to the fuel lines aft of the shutoff valve, which connect the valve to both wing fuel tanks. Although fuel lines were found within the wreckage, impact damage prevented investigators from establishing continuity from the wing tanks to the fuel strainer.
The engine had detached from the firewall and had been displaced aft and upward from the normal position. The engine had sustained moderate damage at the forward lower section. The propeller was displaced from the crankshaft flange. Visual examination of the engine revealed no evidence of preimpact catastrophic mechanical malfunction or fire.
The crankshaft was rotated by hand at the flange and was free and easy to rotate in both directions. Compression was observed in proper order on all four cylinders. The complete valve train was undamaged and was observed to operate in proper order. Normal lift action was observed at each rocker assembly. Clean, uncontaminated oil was observed at all four rockerbox areas. Mechanical continuity was established throughout the rotating group, valve train, and accessory section during hand rotation of the crankshaft.
The cylinders' combustion chambers were examined through the spark plug holes utilizing a lighted borescope. The combustion chambers remained mechanically undamaged, and there was no evidence of foreign object ingestion or detonation. The valves were intact and undamaged. There was no evidence of valve to piston face contact observed. The gas path and combustion signatures observed at the spark plugs, combustion chambers, and exhaust system components displayed coloration that the Lycoming representative said was consistent with normal operation. There was no oil residue observed in the exhaust system gas path. Ductile bending and crushing of the exhaust system components was observed.
The carburetor was not attached to the engine, but was found affixed to the firewall. Investigators removed and disassembled the unit for examination. The examination revealed that the composite floats, venturi, and jet needle were intact. The bowl was dry and no trace of fuel was noted in the accelerator pump chamber. The fuel finger screen was absent of debris. The fuel strainer bowl was attached to the firewall and upon external examination found to be cracked; the strainer screen was removed and found absent of debris.
The vacuum pump was disassembled; both the vanes and shear coupling were intact. The oil filter was examined, and no metallic contamination was noted.
Examination of the propeller revealed that one blade was slightly bent, and the other blade exhibited s-bending with scoring along the length of the leading edge of the blade.
Investigators conducted several interviews with flight instructors and students at the Pan Am Flight Academy Facilities on June 14, 2006.
A student, who had flown with the instructor of the accident flight on the morning of the accident, stated that he was working on his CFI training and enrolled in the same program as the second pilot of the accident flight. He reported that his flight with the accident instructor consisted primarily of spin training, which was the same training curriculum as the accident flight. He stated that the flight started with a mission review, which encompassed the theory of spins and the recovery thereof. After about an hour of the ground training, he completed a preflight inspection of the airplane with the instructor's oversight. After a normal departure, they maneuvered the airplane in a slow flight configuration to the practice area, located just over the Quintero Golf Course (adjacent to the accident site). Upon arriving in the predetermined area, he completed several power-off stalls.
The student further stated that following the practice stall maneuvers, the instructor directed him to complete three incipient spins, all of which were performed to the left. After completing the maneuvers successfully, he performed four spins. Following those maneuvers, he verbally instructed the instructor through two spins in an effort to simulate him being the flight instructor; during this time he was manipulating the airplane's controls. He noted that all of the spins were completed at an altitude of about 6,000 feet msl, and were conducted as "power-off" spins with the engine operating about 1,500 revolutions per minute (rpm). The actual spin maneuver consisted of about one to two revolutions (rotations), where the recovery would occur between 4,000 to 4,500 feet msl. Although he had reviewed the procedures to recover from a spin with the Cessna Pilot's Operator Handbook (relax elevator and input opposite rudder than the direction of rotation), he stated that to recover all he had to do was relax the pressure of the rudder deflection. He recalled his great ease in recovering the airplane from a spin. The total duration of his flight with the instructor was 1.2 hours.
Another Pan Am Flight Academy student was interviewed that had flown with the accident instructor and was working on his CFI training in the same program as the second pilot of the accident flight. The student indicated that he had received spin training from the instructor about 1 week prior to the accident. After making a normal departure, the flight proceeded to the Quintero Golf Course (northwest practice area). Starting at an altitude of 6,500 feet msl the instructor had him perform slow flight while the airplane was configured in a turn. He then completed three to four stalls, with the latter stalls performed while the airplane was in a turn. The instructor then directed him to perform spins, of which they completed six.
The student added that all of the stalls and spins were achieved with a power setting of 1,500 rpm. He stated that the spins would never exceed more than three rotations with the airplane descending 1,800 feet at most. After completing each spin, they would climb back up about 5,500 to 6,500 feet msl. All the spins were conducted to the left, as they could not get the airplane to spin to the right. The duration of the flight was 1.6 hours and he was at the controls throughout the duration of the flight. He noted that the airplane flew well and to recover from the spin, he essentially just had to release the controls and the airplane recovered by itself.
Investigators interviewed a Pan Am Flight Academy instructor about his experiences teaching the second pilot of the accident airplane. He stated that he instructed the second pilot about 10 to 12 flights in both stage checks and as part of his instructor training; he was the second pilot's current instructor. He classified the second pilot's piloting skills as "good" within the training environment, but lacking in areas requiring piloting in situations "outside the box." He recalled the second pilot acting impulsively on numerous occasions when a stressful situation was simulated, such as failing an engine or stalling the airplane.
The instructor recalled two specific occasions that he flew with the second pilot that were memorable due to the pilot's reactions to events that transpired in flight. In both instances the second pilot stiffened on the controls, seizing the yoke, as if petrified. In one flight, he had to physically jab the second pilot in the leg to get him to relinquish the controls. The last event happened June 02, 2006, when the second pilot made a balked landing. The instructor stated that during ground training of spins, the second pilot asked numerous questions about spins and seemed very nervous about the upcoming spin flight. The instructor added that he saw the second pilot on the morning of the accident; he appeared calm and said that he was looking forward to the flight.
Another Pan Am Flight Academy instructor was interviewed regarding his experiences with the second pilot. He stated that he instructed the second pilot for about 1/2 of his training for his multiengine commercial certificate, equating to about 20 hours of flight time. He recalled the second pilot acting impulsively on numerous occasions when a stressful situation was simulated.
Specifically, he recalled an experience where one engine on the multiengine airplane failed to restart while they were performing engine-out procedures. The second pilot appeared panicked that the engine would not restart and the instructor took over the controls. As part of a restart attempt, he pushed the control wheel forward to utilize the airflow to help in mobilizing the propeller. The airplane pitched nose down and the second pilot panicked, grasping the control wheel and holding it firmly aft. The second pilot would not relax his grasp and continued to lock the control wheel toward him. The instructor jabbed the second pilot in the leg in an effort to encourage him to relinquish the controls. The second pilot finally released the control yoke and the instructor reprimanded him; the engine eventually restarted and the flight landed without mishap.
According to the FAA Flight Training Handbook, Advisory Circular (AC) 61-21A, page 154, a spin is described as, "an aggravated stall that results in what is termed 'autorotation' wherein the airplane follows a corkscrew path in a downward direction. The wings are producing some lift and the airplane is forced downward by gravity, wallowing and yawing in a spiral path."
In the normal procedures section of the Cessna 152 POH, page 4-17, the following guidance is given in regards to spins, "Intentional spins are approved in this airplane....It is recommended that, where feasible, entries be accomplished at high enough altitude that recoveries are completed 4,000 feet or more above ground. At least 1,000 feet of altitude loss should be allowed for a 1-turn spin and recovery, while a 6-turn spin and recovery may require somewhat more than twice that amount." It further states that, "The normal entry is made from a power-off stall. As the stall is approached, the elevator control should be smoothly pulled to the full aft position. Just prior to reaching the stall "break", rudder control in the desired direction of the spin rotation should be applied so that full rudder deflection is reached almost simultaneously with reaching full aft elevator."
The POH adds that "A slightly greater rate of deceleration than for normal stall entries or the use of partial power at the entry will assure more consistent and positive entries to the spin. Both elevator and rudder controls should be held full with the spin until spin recovery is initiated. An inadvertent relaxation of either of these controls could result in the development of a nose-down spiral." A note is written stating, "Careful attention should be taken to assure that the aileron control is neutral during all phases of the spin since any aileron defection in the direction of the spin may alter the spin characteristics by increasing the rotation rate and changing the pitch attitude."
In regards to spin training, the POH states, "For the purpose of training in spins and spin recoveries, a 1- to 2-turn spin is adequate and should be used. Up to 2 turns, the spin will progress to a fairly rapid rate of rotation and steep attitude. Application of recovery controls will produce prompt recoveries of from 1/4 to 1/2 of a turn." It further states, "If the spin is continued beyond the 2- to 3-turn range, some change in character of the spin may be noted. Rotation rates vary and some additional slide slip may be felt. Normal recoveries from extended spins may take up to a full turn or more."
Several weeks following the accident, an FAA operations inspector from the Scottsdale Flight Standard District Office (FSDO) conducted a series of spin maneuvers and recoveries in an effort to simulate the conditions at the time of the accident. The inspector, the sole occupant, departed Phoenix in a Cessna 152 about 1100; the total flight duration was about 2 hours. He noted the ambient surface temperature was 103 degrees Fahrenheit with a temperature at 6,500 feet agl averaging about 65 degrees Fahrenheit. He performed a series of two incipient, one, two, and three revolution spins, all of which were conducted to the left. He entered the maneuvers at 6,500 feet agl, with the exception of the three-revolution spins, which he entered at 7,500 feet agl. He obtained the following data from his tests:
One revolution and recovery-
Time from entry to full recovery: 8 seconds
Total altitude loss: 700 to 800 feet
Calculated average rate of descent: 5,625 feet per minute
Two revolutions and recovery-
Time from entry to full recovery: 12 seconds
Total altitude loss: 1,700 feet
Calculated average rate of descent: 8,500 feet per minute
Three revolutions and recovery-
Time from entry to full recovery: 15 seconds
Total altitude loss: 2,900 feet
Calculated average rate of descent: 11,600 feet per minute