La Crosse Municipal Airport
Aircraft Accident/Incident Report

La Crosse, Wisconsin 54603
Saturday, May 10, 2008 22:45 CDT

After transporting a patient to a local hospital and refueling at La Crosse Municipal Airport (LSE), the emergency medical services (EMS) helicopter departed LSE (elevation 656 feet mean sea level [msl]) about 2234 central daylight time (all times in this brief are central daylight time) on a return flight to its base heliport. Dark night visual meteorological conditions (VMC) prevailed at LSE. A ramp services employee at LSE who had observed the helicopter lift off and proceed east-southeast observed “moderate” rain and “fair” visibility at the time of takeoff. Witnesses located southeast of the airport reported hearing the helicopter in flight about the time of the accident, and one witness reported hearing a loud crashing sound. A search was initiated shortly after the crash but was hampered by the terrain and fog that had formed overnight. A search located the helicopter the following morning; the helicopter had impacted trees along a sparsely populated ridgeline about 5 miles southeast of LSE. The elevation of the ridgeline was approximately 1,164 feet msl, with 50- to 60-foot-tall trees in the area initially struck by the helicopter. Distribution of the wreckage was consistent with the helicopter impacting the trees in a nearly level flight attitude under controlled flight. Examination of the helicopter’s engines revealed inlet debris, rotational scoring, and centrifugal turbine blade overload failures consistent with the engines being operated at a moderate to high power level (on both engines) at the time of impact. Nonvolatile memory downloaded from the digital engine control units (DECUs) indicated that both engines were in “flight mode” at the time of impact. Although the left engine main selector switch was observed in the “idle” position after the accident, the lack of anomalies related to the switch and the corresponding DECU in flight mode are consistent with the switch having been moved as a result of impact. No preimpact mechanical malfunctions of the helicopter were found. The reported weather conditions at LSE about 2253 included VMC: calm winds, 8 miles visibility in light rain, few clouds at 1,400 feet above ground level (agl) [2,056 feet msl], overcast clouds at 5,000 feet agl (5,656 feet msl), temperature 10 degrees C, dew point 8 degrees C, and altimeter 29.70 inches of mercury. The preflight weather briefing obtained by the pilot about 1 hour before departure indicated VMC along the route of flight at the time of the briefing but forecasted deteriorating conditions later in the evening after about 2200, including possible instrument meteorological conditions (IMC). Search and rescue personnel reported fog and mist along the ridgeline overnight during the search operations. Additionally, an EMS pilot for another operator reported that when he departed LSE about 2 hours before the accident flight, fog was beginning to form on the west side of the Mississippi River and in the bluffs east of his flight route. He subsequently returned to LSE and declined at least one additional flight that evening due to deteriorating weather conditions. Because of the variability in weather conditions on the night of the accident, the investigation could not determine if the pilot encountered IMC at the time of the accident. The pilot was transferred to the accident operator as a result of the accident operator’s acquisition of his previous employer about 3 months before the accident. The accident pilot was initially qualified as visual flight rules (VFR)-only. An instrument proficiency check was not completed in conjunction with initial training. As a result, the accident pilot was limited to VFR-only operations at the time of the accident. (The accident pilot was current for instrument flight rules [IFR] at his previous place of employment.) During preflight planning, the pilot should have identified any obstacles along the route of flight, including the tree-covered ridgeline. Company records indicated that the pilot had completed one prior flight to LSE within the previous 16-month period, which was about 2 months before the accident. To assist pilots, maximum elevation figures (MEF) are noted on sectional charts and are derived from such features as terrain, trees, and towers. An MEF is specified for each latitude/longitude quadrangle on the chart. Operation at or above the applicable MEF will ensure terrain and obstacle clearance. The MEF for the La Crosse area is 2,200 feet msl. In addition to the MEF, sectional charts depict terrain elevation and specific obstacle height information. If the accident pilot had observed the MEF of 2,200 feet msl, or the terrain elevation/obstacle height information, it would have provided clearance of the tree covered ridgeline. The elevation of the ridge in the vicinity of the tree strikes was approximately 1,164 feet msl. With the 50- to 60-foot-tall trees, the elevation of the treetops was about 1,224 feet msl, providing a margin of approximately 831 feet to the level of the reported “few clouds” and 4,431 feet to the overcast layer of clouds. According to Air Methods Corporation, the accident pilot performed a formal flight risk assessment before the flight. Further, the flight was being tracked by a company flight-following program and received flight dispatch services before the start of the flight. According to the Air Methods General Operating Manual, the pilot’s risk assessment was to be recorded in the pilot’s daily flight log. However, the pilot’s daily flight log was destroyed during the crash. The pilot entered a risk assessment of “A” (normal operations) into the flight dispatch computer system before the flight. While the weather in the LSE area was marginal at the time of the accident, it was above the minimums required by Federal Aviation Administration (FAA) regulations and the operator’s procedures. There were no identified weather risks that would have warranted classifying the flight in the risk assessment category “B” (caution). A radar altimeter was installed on the helicopter and, according to Air Methods, was normally set to 500 feet for night flight. On December 21, 2007, the National Transportation Safety Board (NTSB) issued Safety Recommendations A-07-111 and -112, asking the FAA, respectively, to require helicopter EMS (HEMS) operators to install radar altimeters in all helicopters used in HEMS night operations and ensure that the minimum equipment lists for helicopters used in HEMS operations require that radar altimeters be operable during flights conducted at night. On March 10, 2008, the FAA stated that it agreed with the intent of these recommendations and was considering rulemaking to require all 14 Code of Federal Regulations Part 135 HEMS operators conducting night HEMS operations to have an operable radar altimeter installed in the helicopter. On August 17, 2009, the FAA indicated that it revised FAA Order 8900.1, “Flight Standards Information Management System,” to provide standards and procedures for inspectors to evaluate flat light or whiteout training programs for all helicopter operators. The FAA also stated that an in-progress notice of proposed rulemaking (NPRM) for air ambulance and commercial helicopter operations would address the safety intent of these recommendations. On March 12, 2010, the NTSB stated that, although it agrees that increased training for pilots may be of benefit in avoiding accidents where radar altimeters are needed, issuing guidance and standards for such training is not responsive to these recommendations. The NTSB further indicated that it is pleased to learn that the planned NPRM will include language proposing the recommended requirements for radar altimeters. Pending the issuance of a final rule requiring (1) the installation of radar altimeters in all helicopters used in HEMS night operations and (2) the inclusion of a requirement on the minimum equipment lists that these altimeters be operable on all helicopters during HEMS flights conducted at night, Safety Recommendations A-07-111 and 112 were classified “Open—Acceptable Response.” In this accident, the radar altimeter should have alerted the pilot when terrain clearance dropped below 500 feet agl. Although Air Methods’ company policy was to set the radar altimeter to 500 feet for night flight, the NTSB was unable to verify that the radar altimeter was, in fact, turned on and set to 500 feet for the accident flight. Assuming that the radar altimeter was turned on, set to 500 feet, and functioning properly at the time of the accident, the pilot likely would have received numerous alerts between 4 nautical miles (nm) and 2 nm from the point of impact and constant alerts from 2 nm to the point of impact. The NTSB was unable to determine why the pilot did not take corrective action in response to the alerts from the radar altimeter or, if the pilot did take corrective action, why it was ineffective. There was no record of any maintenance issues regarding the accident helicopter’s radar altimeter. The helicopter was not equipped with a terrain awareness and warning system (TAWS). TAWS detects terrain or other obstructions along the flightpath and provides an audible alert to warn the pilot to take corrective action. TAWS looks forward to detect terrain and obstacles in front of the aircraft, while the radar altimeter looks down to measure the distance between the aircraft and the terrain below the aircraft. In addition, TAWS issues an audible alert, whereas the radar altimeter issues a visual alert. Typically, a HEMS pilot flying at night would benefit from an audible alert because the pilot would be looking forward out of the cockpit for a VFR flight; the radar altimeter is used mainly in the IFR environment. Further, because the clouds were low on the night of the accident, the pilot may have been deliberately flying below 500 feet to avoid the clouds. In that case, the pilot may have been purposely ignoring radar altimeter illuminations, but TAWS would have captured his attention because it looks forward and provides an audible alert. On February 7, 2006, the NTSB issued Safety Recommendation A-06-15, which asked the FAA to require EMS operators to install TAWS on their aircraft and to provide adequate training to ensure that flight crews are capable of using the systems to safely conduct EMS operations. The FAA responded that, while it would work with industry to address issues related to the installation of TAWS on EMS aircraft, it would address the issue of controlled flight into terrain by emphasizing effective preflight planning. The FAA further stated that the Radio Technical Commission for Aeronautics established a committee tasked with developing helicopter TAWS (H-TAWS) standards and that, in March 2008, the commission completed the development of minimum operational performance standards for H-TAWS. On December 17, 2008, the FAA published Technical Standard Order C194, “Helicopter Terrain Awareness and Warning System,” based on the commission standards. On January 23, 2009, the NTSB indicated that the continuing delays in development of a final rule to require H-TAWS were not acceptable. On November 4, 2009, the FAA responded by indicating that it was developing an NPRM to address this recommendation and that it planned to complete work on the NPRM in January 2010. The NPRM has not yet been issued. On November 13, 2009, the NTSB reiterated Safety Recommendation A-06-15 in its report regarding the September 27, 2008, accident involving an Aerospatiale SA365N1, N92MD, operated by the Maryland State Police, which crashed during approach to landing near District Heights, Maryland. On February 18, 2010, the NTSB indicated that it remained concerned about the time required to develop and issue this requirement. The NTSB classified Safety Recommendation A-06-15 “Open—Unacceptable Response,” pending adoption of a requirement that all EMS operators equip their aircraft with and use TAWS. An installed and operable H-TAWS unit would likely have alerted the accident pilot to the rising terrain and provided an opportunity to climb, thereby allowing the pilot to avoid the ridgeline. Member Sumwalt did not approve this brief and probable cause. Member Sumwalt filed a dissenting statement that can be found in the public docket for this accident.

The pilot’s failure to maintain clearance from trees along the top of a ridgeline due to inadequate preflight planning, insufficient altitude, and the lack of a helicopter terrain awareness and warning system. Member Sumwalt did not approve this brief and probable cause. Member Sumwalt filed a dissenting statement that can be found in the public docket for this accident.