ERA25FA151

The pilot’s exceedance of the airplane’s critical angle of attack while landing and the flight instructor’s inadequate remedial action, which resulted in an aerodynamic stall/spin at an altitude too low for recovery.

The reported purpose of the flight was because the pilot receiving instruction and his flight instructor both had a free day to go flying. The flight logbook of the pilot receiving instruction showed that he had been receiving instruction toward his commercial pilot certificate from the flight instructor. After picking up the flight instructor the pilot took off and completed two circuits in the airport traffic pattern. Both landing approaches during these circuits were consistent with a power-off 180° accuracy approach and landing. The third circuit was consistent with the previous two approaches. During the third approach, as the airplane neared the ground, data recovered from avionics onboard the airplane showed that the airplane’s pitch began to increase while the airplane was in a steep left bank. Simultaneously, the airspeed began to decrease below the stall speed listed in the airplane Pilot’s Operating Handbook (POH). The airplane then suddenly rolled right, and the pitch decreased. The airplane impacted the ground before the runway threshold in the displaced threshold area and was heavily damaged by postimpact fire. Postaccident examination of the wreckage found no evidence of any preimpact mechanical malfunctions or failures with the airframe or engine that would have precluded normal operation. The power-off 180° accuracy approach and landing was a maneuver that was required to be demonstrated in order to obtain a commercial pilot certificate. This maneuver involved reducing engine power to idle while on the downwind leg of the traffic pattern and attempting to land on or just beyond a preselected point on the runway. Performance of this maneuver required the pilot to assess the risks associated with wind, airplane performance, and low-altitude maneuvering, to include stalls or spins. One of the common errors associated with this maneuver was a pilot’s attempt to “stretch” a glide during an undershot approach. Given the airplane’s observed pitch, bank, and airspeed during the final moments of the accident flight, it is likely that, during the power-off 180° accuracy approach and landing maneuver attempt, the pilot receiving instruction misjudged the landing, which resulted in an undershot approach. He then likely attempted to stretch the glide, which resulted in the airplane exceeding the critical angle of attack and entering an aerodynamic stall/spin at an altitude too low to successfully recover. Additionally, the flight instructor should have been able to recognize the airplane’s attitude and airspeed as the airplane approached the low altitude aerodynamic stall and been able to intervene in sufficient time to prevent it. Although there was no clear evidence that the pilot receiving instruction was impaired by effects of diabetes or its treatment at the time of the accident, the pilot receiving instruction had also used prescription medications, including clomiphene and chloroquine, that were not reported at his last aviation medical examination, and that, while not typically impairing, could have had adverse side effects. In addition, the pilot receiving instruction had cardiovascular conditions, including moderate coronary artery disease, high blood pressure, and diabetes, that were associated with increased risk of an impairing or incapacitating cardiovascular event, such as arrythmia, heart attack, or stroke. Although there is no autopsy evidence that such an event occurred, such an event cannot be excluded by autopsy evidence alone. The flight instructor’s abnormally elevated carboxyhemoglobin level can be attributed to effects of the postimpact fire. In-flight carbon monoxide poisoning was unlikely given the fact that the pilot receiving instruction did not have elevated carboxyhemoglobin.

The Airplane Flying Handbook (FAA-H-8083-3C) Chapter 9 describes the Power-Off 180° Accuracy Approach and Landing, stating the following: “The 180° power-off approach is executed by gliding with idle power from a given point on a downwind leg to a preselected landing spot. It is an extension of the principles involved in the 90° power-off approach just described. The objective is to further develop judgment in estimating distances and glide ratios, in that the airplane is flown without power from a higher altitude and through a 90° turn to reach the base-leg position at a proper altitude for executing the 90° approach. The 180° power-off approach requires more planning and judgment than the 90° power-off approach. In the execution of 180° power-off approaches, the airplane is flown on a downwind heading parallel to the landing runway. The altitude from which this type of approach is started varies with the type of airplane, but should usually not exceed 1,000 feet above the ground, except with large airplanes. Greater accuracy in judgment and maneuvering is required at higher altitudes. When abreast of or opposite the desired landing spot, the throttle is closed and altitude maintained while decelerating to the manufacturer’s recommended glide speed or 1.4 VSO. The point at which the throttle is closed is the downwind key position. The turn from the downwind leg to the base leg is a uniform turn with a medium or slightly steeper bank. The degree of bank and amount of this initial turn depend upon the glide angle of the airplane and the velocity and direction of the wind. Again, the base leg is positioned as needed for the altitude or wind condition. Position the base leg to conserve or dissipate altitude so as to reach the desired landing spot. The turn onto the base leg is made at an altitude high enough and close enough to permit the airplane to glide to what would normally be the base key position in a 90° power-off approach. Initial flaps may be extended prior to the base key position if needed. Although the base key position is important, it should not be overemphasized nor considered as a fixed point on the ground. Many inexperienced pilots may gain a conception of it as a particular landmark, such as a tree, crossroad, or other visual reference, to be reached at a certain altitude. This misconception leaves the pilot at a total loss any time such objects are not present. Both altitude and geographical location should be varied as much as is practical to eliminate any such misconceptions. After reaching the base key position, the approach and landing are the same as in the 90° power-off approach. Common errors in the performance of power-off accuracy approaches are: 1. Downwind leg is too far from the runway/landing area. 2. Overextension of downwind leg resulting from a tailwind. 3. Inadequate compensation for wind drift on base leg. 4. Skidding turns in an effort to increase gliding distance. 5. Failure to lower landing gear in retractable gear airplanes. 6. Attempting to “stretch” the glide during an undershoot. 7. Premature flap extension/landing gear extension. 8. Use of throttle to increase the glide instead of merely clearing the engine. 9. Forcing the airplane onto the runway in order to avoid overshooting the designated landing spot. The commercial pilot for airplane category airman certification standard (FAA-S-ACS-7B) Area of Operation IV. Takeoffs, Landings, and Go-Arounds; Task M. Power-Off 180° Accuracy Approach and Landing described the maneuver objective, risk management, and skills. It stated that the performance of this maneuver required the pilot to identify, assess, and mitigate the risks associated with wind, airplane performance, and low-altitude maneuvering, to include stalls or spins. Fueling records from RMG showed the airplane was last fueled with 54.2 gallons of 100LL aviation fuel on the day of the accident at 1321. The fueler who fueled the airplane reported that he had filled both of the airplane’s wing fuel tanks fully. Fueling records from 9A5 showed that no fuel was purchased between the time the accident airplane arrived and the time it departed. The data recovered from the onboard avionics contained basic flight and engine parameters. The recording rates of the parameters varied, from engine data being recorded every 4 seconds to GPS data being recorded at 4 samples per second. According to the Cirrus SR22 POH the stall speed with 50% flaps ranged from 78 kts to 80 kts indicated airspeed (depending on the airplane’s center of gravity) when in a 45° bank. The Georgia Bureau of Investigation, Department of Forensic Sciences, Office of the Medical Examiner ruled the cause of death for the pilot receiving instruction and the flight instructor as thermal injuries and their manner of death as accident. The autopsy of the pilot receiving instruction identified coronary artery disease, with plaque causing 60% narrowing of the left anterior descending coronary artery, 50% narrowing of the left circumflex coronary artery, and 30% narrowing of the right coronary artery. The remainder of the autopsy, including visual examination of the heart, did not identify other significant natural disease. Extensive thermal injury was present, without airway soot. The FAA Forensic Sciences Laboratory performed toxicological testing of postmortem specimens from the pilot receiving instruction. Clomiphene, chloroquine, tadalafil, metformin, lisinopril, and atorvastatin were found in heart blood and urine. Glucose was measured at 19 mg/dL in vitreous fluid and was not detected in urine. Carboxyhemoglobin was reported as not detected in heart blood. Clomiphene is a prescription medication that can be used in the treatment of low testosterone. It is not typically impairing but may sometimes have adverse side effects including blurry vision or seeing spots or flashes. The FAA allows Aviation Medical Examiners to issue medical certification to pilots who use clomiphene for low testosterone, subject to certain specific requirements, including a 14-day initial ground trial and confirmation of no visual side effects. Chloroquine is a prescription medication that can be used for malaria prophylaxis and treatment. It also may be used to treat conditions including lupus and rheumatoid arthritis. Additionally, chloroquine has been prescribed for prevention or treatment of the COVID-19 virus, but has not been proven to be effective for such use. Although chloroquine does not typically have direct impairing effects, it may have adverse side effects including retinopathy and heart rhythm problems. FAA medical certification of pilots on chloroquine depends on the underlying condition and effects of treatment. Tadalafil is a prescription medication commonly used to treat erectile dysfunction, as a sexual enhancement aid, and to treat symptoms of an enlarged prostate. Tadalafil is not typically impairing, although the FAA states that pilots who use it on an as-needed basis should wait 24 hours after use before flying, to monitor for side effects. Metformin is a prescription oral medication commonly used for blood sugar control in diabetes and prediabetes. Metformin is not typically impairing, and may be acceptable for FAA pilot medical certification if the underlying condition is determined to be acceptable. Lisinopril is a prescription medication commonly used to treat high blood pressure. Lisinopril is not generally considered impairing. Atorvastatin is a prescription medication commonly used to control cholesterol and reduce cardiovascular risk. Atorvastatin is not generally considered impairing. According to the flight instructor's autopsy report, a portable co-oximetry screening test measured carboxyhemoglobin at 15.6%, and Georgia Bureau of Investigation testing of heart blood measured carboxyhemoglobin at 20%, plus or minus 5%. The FAA Forensic Sciences Laboratory performed toxicolo