Lone Rock, WI, USA
N5039S
Piper PA-28R-200
The airplane was substantially damaged during an in-flight collision with terrain following an inadvertent stall on short final. The pilot reported that the instrument flight rules (IFR) flight had initially been operating above a broken to overcast cloud layer. However, about the mid-point of the trip the flight encountered instrument meteorological conditions (IMC) and light rime ice. The pilot stated that he requested a higher altitude in an attempt to avoid the icing conditions, but air traffic control cleared him to a lower altitude due to the flight's proximity to its intended destination. The flight remained in IMC as it was vectored for an instrument approach. At the missed approach point, the pilot did not have the airport in sight due ground snow cover and his unfamiliarity with the area. He executed a missed approach. While being provided with radar vectors for another approach, the pilot obtained visual contact with the airport. When he entered visual flight rules (VFR) conditions, he cancelled the IFR flight plan and entered a traffic pattern for runway 36. The pilot reported that on short final the airplane drifted left of the runway centerline. He applied a little power in an attempt to get re-aligned. The pilot stated: "The aircraft started rolling left. I applied full power and attempted to abort my landing. The aircraft engine responded but we completely rolled until inverted and subsequently made contact with the ground." In a follow-up interview, the pilot stated that the aircraft had accumulated rime ice along the leading edges of the wings. An AIRMET for occasional moderate rime or mixed icing below 10,000 feet mean sea level was in effect at the time of the flight. A certified re-recording of the weather briefing was provided to the NTSB. During the briefing, the pilot was informed of the AIRMET and of a pilot report of light rime ice along his route of flight. The pilot had received his instrument rating seven weeks prior to the accident. He reported 2.5 hours of actual instrument flight time and minimal experience with in-flight icing conditions. Federal Aviation Administration publications state that ice formation on an aircraft's flight surfaces may adversely affect performance and control. They note that with ice accretion an "aerodynamic stall may occur with little or none of the usual cues in advance of the stall or at the occurrence of stall."
On February 7, 2004, at 1320 central standard time, a Piper PA-28R-200, N5039S, piloted by an instrument-rated private pilot, was substantially damaged following an in-flight loss of control on final approach to runway 36 (1,988 feet by 60 feet, asphalt) at the Tri-County Regional Airport (LNR), Lone Rock, Wisconsin. The airplane impacted terrain inverted approximately 200 feet short of the runway. The flight was operating under 14 CFR Part 91 and was not on a flight plan at the time of the accident. Visual meteorological conditions (VMC) prevailed. The pilot and two passengers sustained minor injuries. The flight departed the John H. Batten Airport (RAC), Racine, Wisconsin, at 1200 on an Instrument Flight Rules (IFR) flight plan. In his written statement, the pilot reported that after departure from RAC the flight climbed to 4,000 feet mean sea level (msl) and was operating in VMC above the cloud layer. In the vicinity of Madison, Wisconsin (MSN), the flight entered instrument meteorological conditions (IMC) and encountered light rime icing conditions. The pilot stated that he requested a higher altitude in an attempt to avoid the area of icing. However, due to the aircraft's proximity to LNR, air traffic control (ATC) instructed the pilot to descend to 3,200 feet msl. According to the pilot, the aircraft remained in IMC at 3,200 feet msl. The aircraft was given radar vectors for an instrument approach at LNR. The pilot reported that on arrival at the missed approach point, he did not have the airport in sight due to the snow cover and his unfamiliarity with the area. He executed a missed approach. The pilot stated that as the flight was being radar vectored for another approach he made visual contact with the airport. Upon nearing the LNR VHF Omni Range (VOR), the flight encountered VMC and the pilot elected to cancel the IFR flight plan. The pilot reported that he entered a traffic pattern for runway 36. He noted that the aircraft was configured with 25 degrees flaps and crossed the runway threshold at just below 85 miles per hour (mph). He stated: "On short final I drifted left of centerline and applied a little power and attempted to get re-aligned. The aircraft started rolling left. I applied full power and attempted to abort my landing. The aircraft engine responded but we completely rolled until inverted and subsequently made contact with the ground." In a follow-up interview, the pilot stated that the aircraft had accumulated rime ice along the leading edges of the wings, although he was not sure of the thickness. He also noted that there were no failures or malfunctions associated with the engine or airframe prior to the accident. An AIRMET for occasional moderate rime or mixed icing in clouds and/or precipitation below 10,000 feet msl was in effect for the route of flight at the time. The conditions were forecast to continue until 1500. At 1125, a pilot reported light rime icing at 2,700 feet msl, 5 miles south of MSN. Green Bay Automated Flight Service Station (AFSS) provided a certified re-recording of the pilot's pre-flight weather briefing. The pilot requested a briefing for an IFR flight from RAC to LNR and return. During the briefing, the pilot was notified of AIRMETs for IFR and icing conditions along the route of flight. He was also provided with the pilot report of light rime icing in the vicinity of Madison. The pilot received an instrument rating on December 21, 2003. He reported 2.5 hours of actual instrument flight time, of which 0.5 were in the previous 30 days. In his report, he stated he should have been more assertive with ATC in his attempt to avoid the icing conditions. According to the aircraft manufacturer, the airplane's stall speed with landing gear and flaps extended was 64 mph. With the gear and flaps retracted, the stall speed was 70 mph. FAA Advisory Circular (AC) 61-23C, Pilot's Handbook of Aeronautical Knowledge, states that in-flight "ice formation will alter the shape of the airfoil and adversely affect all aspects of airplane performance and control. As the ice forms on the airfoil, especially the leading edge, the flow of air over the wing is disrupted. This disruption of the smooth airflow causes the wing to lose part or all of its lifting efficiency." FAA AC 61-67C, Stall and Spin Awareness Training, states that "any contamination or alteration of the leading edge caused by factors such as . . . ice can significantly alter the aerodynamic characteristics of the wing." It goes on to note that an "aerodynamic stall may occur with little or none of the usual cues in advance of the stall or at the occurrence of stall."
The pilot's continued flight into icing conditions resulting in ice accretion on the wing and his failure to maintain airspeed resulting in a stall.
Source: NTSB Aviation Accident Database
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