Anchorage, AK, USA
N544LM
BOMBARDIER LEARJET CORP. 35A
As the medical transport flight descended below the cloud cover during dark night, instrument meteorological conditions while on approach, the flight crew discovered that the first officer's windscreen was entirely covered with ice and that she would not be able to continue the approach. Although the captain's windscreen was partially covered with ice, he could still see the runway, so he took control of the airplane and continued the approach. The flight crew then confirmed that the windscreen heating and alcohol anti-ice systems were on. As the airplane passed over the runway threshold, the captain's windscreen abruptly iced over, and he had no forward visibility as the airplane's main landing gear wheels touched down. Unable to see the runway ahead and with limited visibility to each side, the flight crew attempted to activate the engine thrust reversers to slow the landing roll, but the airplane subsequently veered to the right of the runway centerline, and the right wing collided with a snow berm. The pilots reported no preincident mechanical malfunctions or failures that would have precluded normal operation. About 15 minutes before the incident, the approach controller at an airport about 7 miles northeast of the incident airport advised the destination airport's north radar position controller that the pilot of another airplane had reported that he was "going around" due to severe icing on the airplane's canopy. No record was found indicating that this pilot report (PIREP) was relayed to the incident flight crew or other aircraft operating near the incident airport. Both airports are under the control of the same approach control facility. The meteorological conditions at the time of the accident were conducive to a very light freezing or frozen precipitation environment very close to or at the surface. Therefore, it is likely that the airplane encountered significant in-flight icing conditions during the approach and landing that exceeded the capabilities of the airplane's anti-ice systems. In addition, if the pilots had been made aware of the severe icing PIREP from the nearby airport, they likely would have had other options available for landing. The Federal Aviation Administration has indicated that it will form a PIREP working group to address issues associated with the dissemination of PIREPs.
On March 5, 2012, about 2154 Alaska standard time, a Bombardier Learjet, model 35A airplane, N544LM, sustained minor damage while landing on runway 7R at the Ted Stevens Anchorage International Airport, Anchorage, Alaska. The airplane was operated by Aero Air LLC., Hillsboro, Oregon, under contract to LifeMed Alaska, Anchorage, Alaska, as an instrument flight rules (IFR) patient transport flight under 14 CFR Part 135. None of the six people aboard, the airline transport certificated captain, the commercial certificated first officer, two flight paramedics, a flight nurse, and the patient, reported any injuries. Dark night, visual meteorological conditions prevailed, and an instrument flight rules (IFR) flight plan had been filed for the flight from Kenai, Alaska. The flight departed Kenai about 2130. During an on-scene interview with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on March 5, the captain reported that the trip to Anchorage was to be flown by the first officer. He said that as the flight neared Anchorage, they were cleared for the RNAV GPS instrument approach to runway 7R. As the flight descended below the cloud cover, the pilots discovered that the first officer's windscreen was entirely covered with ice, and she would be unable to continue the approach. The captain said that his windscreen was also partially covered with ice, but he could still see the runway environment ahead, so he took control of the airplane to continue the approach. After he confirmed that the windscreen anti-ice system was on, which provides bleed air heat to both windscreens, he also activated the alcohol anti-ice system, which works by pumping alcohol onto the captain's windscreen, as well as the nose radome. The captain said that as the airplane passed over the runway threshold, just before touchdown, his windscreen abruptly iced over, and he had no forward visibility as the airplane's main landing gear wheels touched down. Unable to see the runway ahead, and with limited visibility to each side, the crew attempted to activate the engine thrust-reversers to slow the landing roll, but the airplane subsequently veered to the right of runway centerline, and the right wing collided with a snow berm. The airplane pivoted to the right, continued off the runway, and came to rest embedded in a snow bank, on the right side of Runway 07R. Both pilots noted that there were no preaccident mechanical anomalies with the airplane. The NTSB IIC removed the cockpit voice recorder (CVR), and sent it to the NTSB vehicle recorder laboratory in Washington, DC for review. After review of key events on the CVR, it was determined that the audio did not offer any additional information that had not already been obtained from the flightcrew. No CVR listening group was convened, and no CVR transcript was created. A summary report of the CVR audio is included in the public docket for this accident. METEOROLOGICAL INFORMATION An NTSB senior meteorologist did a comprehensive study of the weather conditions around the Ted Stevens Anchorage International Airport at the time of the incident, which included a review of pilot reports of other aircraft operating nearby. Ted Stevens Anchorage International Airport The closest weather reporting facility was the Ted Stevens Anchorage International Airport. At 2153, about 1 minute before the incident, a routine weather observation was reporting, in part: Wind, 350 degrees (true) at 4 knots; visibility, 9 statute miles; clouds and sky condition, few at 1,300 feet, 2,000 feet scattered, 4,400 feet overcast; temperature, 14 degrees F; dew point, 10 degrees F; altimeter, 29.80 inches Hg. Remarks; Snow ended at 2149. At 2241, about 47 minutes after the accident, a special weather observation was reporting, in part: Wind, 340 degrees (true) at 6 knots; visibility, 3 statute miles with light snow and mist; clouds and sky condition, few at 500 feet, 1,100 feet broken, 1,900 feet overcast; temperature, 14 degrees F; dew point, 10 degrees F; altimeter, 29.80 inches Hg. Remarks; station with a precipitation discriminator, snow began at 2203, trace hourly precipitation. At 2253, about 59 minutes after the accident, a routine weather observation was reporting, in part: Wind, 010 degrees (true) at 3 knots; visibility, 2 statute miles with light freezing drizzle with mist; clouds and sky condition, few at 600 feet, 1,100 feet broken, 1,900 feet overcast; temperature, 16 degrees F; dew point, 12 degrees F; altimeter, 29.80 inches Hg. Remarks; station with a precipitation discriminator, freezing drizzle began at 2253 and snow began at 2203 and snow ended at 2253. Elmendorf Air Force Base Another official weather observation station was Elmendorf Air Force Base, about 7 miles northeast of the Ted Stevens Anchorage International Airport. At 2155, about 1 minute before the accident, a routine automated weather observation was reporting, in part: Wind, calm; visibility, 10 statute miles; clouds and sky condition, 700 feet broken, 3,800 feet overcast; temperature, 14 degrees F; dew point, 10 degrees F; altimeter, 29.80 inHg. Remarks: station with a precipitation discriminator, unknown precipitation began at 2122 and unknown precipitation ended at 2132 and snow ended at 2103. Anchorage Area Pilot Reports Federal Aviation Administration (FAA) quality control personnel at the Anchorage Air Traffic Control Tower (ATCT) provided the NTSB meteorologist with a recording of the Anchorage Approach North Radar air traffic control (ATC) position. The recording revealed communication between Elmendorf Air Force Base control tower (EDF) and the Anchorage Approach North Radar ATC position at 2139, about 15 minutes before the incident, with EDF advising the North Radar position of an F-16 airplane "going around" due to severe icing on his canopy. There was no record that this pilot report was relayed to the incident airplane, or another aircraft operating near the Ted Stevens Anchorage International Airport. A complete copy of the NTSB's metrological study and attachments are included in the public docket of this incident.
The flightcrew's loss of visual reference to the runway after encountering severe in-flight icing conditions, which resulted in a loss of control while landing and exceedence of the capabilities of the airplane's windscreen anti-ice systems. Contributing to this incident was the failure of the approach controller to relay a pilot report of severe icing conditions near the route of flight to the incident flight crew.
Source: NTSB Aviation Accident Database
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