Cirrus SR22 N401SC

Summary

On 25 January 2017 at about 21:39 local time, a Cirrus SR22 registered N401SC was involved in an accident near San Antonio, Texas, United States. One person was on board and one died. The aircraft was destroyed. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

25 January 2017 at 21:39

Classification

Accident

Location

San Antonio, Texas, United States

Nearest airport

Stinson Municipal (SSF)

Coordinates

29.3269, -98.4581

Aircraft

Cirrus SR22

Registration

N401SC

Category

Airplane

Year built

2004

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

San Antonio → San Antonio

Aircraft damage

Destroyed

Weather

VMC

Light

Day

NTSB number

CEN17FA084

1 person died.

The pilot's uncoordinated flight control inputs and subsequent inadvertent cross-control aerodynamic stall in the airport traffic pattern that resulted in a loss of control and uncontrolled descent with insufficient altitude for recovery.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

The pilot was maneuvering in the airport traffic pattern at the time of the accident.  The pilot entered a continuous right turn from downwind toward the final approach course when he abruptly lost control.  A witness stated that the airplane wings were "totally vertical" before it nosed over and descended toward the ground.  A second witness also reported that the airplane wings were nearly vertical before it descended below the tree line.  He added that the engine sounded "fine." An NTSB performance study revealed that after the airplane entered the airport traffic pattern, it began a continuous right turn from downwind toward the final approach course suggesting that the pilot did not fly a traditional rectangular traffic pattern, but instead flew a circling base to final pattern. The airplane approached the extended runway centerline in a 48° right bank, at 103 kts and about 220 ft agl. Lateral accelerations began to increase shortly before the accident and varied between 0.37g and 0.62g for the final portion of the flight. The lateral accelerations were consistent with sideslip angles of 15° to 20° during the final turn. The calculated angle-of-attack (AOA) of the wing subsequently exceeded the critical AOA and the airplane entered a descent which ultimately reached 1,800 fpm. Although the pilot's control inputs were not directly recorded, the large lateral accelerations are consistent with left rudder input and an uncoordinated flight condition for the airplane. The accident site was located in a wooded area about 1/2 mile southeast from the landing runway threshold. Airframe and engine examinations did not reveal evidence of any anomalies consistent with a preimpact failure or malfunction. The Pilot's Operating Handbook noted that extreme care must be taken to avoid uncoordinated or accelerated control inputs when close to the stall, especially when close to the ground. If, at the stall, the flight controls are misapplied and accelerated inputs are made to the elevator, rudder, and/or ailerons, an abrupt wing drop may be felt and a spiral or spin may be entered. The FAA Airplane Flying Handbook (FAA-H-8083-3B) noted that coordinated flight is important to maintaining control of the airplane. Situations can develop when a pilot is flying in uncoordinated flight and depending on the flight control deflections, may support pro-spin flight control inputs. This is especially hazardous when operating at low altitudes, such as in the airport traffic pattern. A cross-control stall occurs when the critical AOA is exceeded with aileron pressure applied in one direction and rudder pressure in the opposite direction, causing uncoordinated flight. The aerodynamic effects of an uncoordinated, cross-control stall can occur with very little warning and can be deadly if it occurs close to the ground. The nose may pitch down, the bank angle may suddenly change, and the airplane may continue to roll to an inverted position, which is usually the beginning of a spin.

Quoted verbatim from the NTSB record.