# NTSB SEA97LA109: Learjet 35A, N1AH, Great Falls, MT, May 16, 1997 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: May 16, 1997, 13:14 local (19:14 UTC) - Place: Great Falls, MT - Coordinates: 47.509712, -111.270484 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=47.5097&lon=-111.2705&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 2 minor - Status: Completed, report July 13, 1998 - Report: Approved by Office Director - NTSB case key (mKey): 42604 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA97LA109 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/42604/pdf - Page: https://openairdocs.org/ntsb/SEA97LA109 ## Probable cause the captain's inadequate preflight planning/preparation, and the subsequent improper response to a simulated loss of engine power, resulting in liftoff at an airspeed below that for which sustained flight was possible. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of control - in flight, takeoff - preflight planning/preparation - inadequate, pilot in command (cause) - emergency procedure - improper (cause) - airspeed(vmc) - not obtained/maintained (cause) - aircraft control - not possible - In flight collision with terrain/water, descent - uncontrolled ## Analysis The captain reported: 'Shortly after V1...there was a loss of power to the left engine....' (FAR Part 1 defines V1 as takeoff decision speed.) However, the first officer, who was the pilot flying, stated the captain retarded power on the left engine as a training exercise. The first officer stated there was no preflight discussion of emergency procedure practice. The airplane became airborne about 3,500 feet down the runway; the crew subsequently lost control of the aircraft, and it crashed to the left of the runway, and a fire erupted. The crew escaped with minor injuries. A teardown of the left engine was performed under FAA supervision at the engine manufacturer's facilities; the engine manufacturer reported that damage found during the teardown 'was indicative of engine rotation and operation at the time of impact....' Both airspeed indicator bugs were found set 9 to 11 knots below the V1 speed on the takeoff and landing data (TOLD) card. No evidence of an aircraft or engine malfunction, to include inflight fire, was found at the accident site. ## Factual narrative On May 16, 1997, approximately 1314 mountain daylight time, a Learjet 35A, N1AH, being operated by Professional Flight Crew Services of Melbourne, Florida (d/b/a First Air Jet Charter), a 14 CFR 135 on-demand air taxi certificate holder, crashed during an attempted takeoff from runway 21 at Great Falls International Airport, Great Falls, Montana. The airplane was substantially damaged by impact forces and a post-crash fire, and the two pilots (an airline transport pilot-in-command and a commercial pilot second-in-command) received minor injuries. The flight was to be a 14 CFR 91 positioning flight to return to the aircraft's home base of Dallas Love Field, Dallas, Texas, and there were no passengers on board. Visual meteorological conditions prevailed at the time of the accident, and the flight was on an instrument flight rules (IFR) flight plan. The pilots reported that the first officer was the pilot flying at the time of the occurrence. In a written statement attached to the operator's accident report, the captain stated the following: The take off [sic] was normal with the exception of gusty cross winds[;] all standard call outs were made at the appropriate times during the take-off roll. Shortly after [V1, critical engine failure speed] was reached there was a loss of power to the left engine. The aircraft became airborne and the Pilot-Flying was handling the situation well when the aircraft pitched up and banked to the left[.] I then assisted on the controls but was unable to control the aircraft. The aircraft began to roll left and right as airspeed began to deteriorate[;] we leveled the wings just before impact.... In the first officer's written statement, also attached to the operator's accident report, the first officer stated the following: After calling V1...[the captain] informed me that we had lost engine power on one of the engines....Before I could respond, the airplane lifted off....And then, the nose pitched up and the wings rocked back and forth, first to the left, and then very aggressively to the right where it looked like we were about to hit the ground with our right tip at a 45 degree angle. As we dropped, the plane came down right side up and hit the ground hard.... We continued to bounce [straight] ahead on the grass next to the runway...finally coming to rest.... ...As we looked at each other, surprised to be alive [the captain] told me "If anybody asks, we lost the left engine." I said "I couldn't live with that" but as we watched the aircraft burn, I said "we are lucky to be alive, I can live with the truth." ...The FAA had happened to be in town and were there at the scene. Due to our conflict, I tried to let [the captain] tell the story and he stuck to his portion of the truth. Since what he said was all true I agreed that was how I saw it. However we left out one minor detail. [The captain] had pulled the power back on me as a training exercise.... ...[The captain] also told me that at the point that we lost control, he gave me power back in the left engine. ...the target [V] speeds set in the airspeed indicators may have been set with the wrong speeds. This may have caused V1 to be called out early....With the V1 speed being called early the pilot flying would continue the take off which in turn would cause control problems. My belief is that we were at a speed below V1 which meant that we should have powered back and abort[ed] the take off.... Air traffic controllers at Great Falls who saw the aircraft reported that it became airborne, reaching an altitude of about 50 to 75 feet above ground level and flying for 1/4 to 1/2 mile, before impacting on the airport to the left of the runway and coming to a stop. Investigators from the FAA and Learjet conducted an on-site investigation. The Learjet investigator's on-site examination field notes described the accident aircraft's flight path as follows: ...The aircraft lifted off at approximately 3500' [down the runway] and entered a left turn to a heading of 184 [degrees] for approximately 1154'. The aircraft then turned to a heading of 197 [degrees] for approximately 1822' before impacting the ground with the right tip tank. The right tip tank ruptured....Fuel from the right tip tank ignited. The aircraft bounced and spun 180 [degrees]. The airplane...tracked across the ground on a heading of 209 [degrees] for approximately 1093'. The aircraft came to rest facing north 1.24 NM (7534') from the end of runway 21. Photographs taken by the Learjet investigator showed a takeoff and landing data (TOLD) card in the aircraft cockpit with a computed V1 speed of 127 knots, VR (rotation speed) of 134 knots, and V2 (takeoff safety speed) of 137 knots (the takeoff distance was not filled in on the card); the captain's airspeed indicator "bug" set at 116 knots; the first officer's airspeed indicator "bug" set at 118 knots; the left engine turbine temperature indicator captured at 371 degrees C (within the normal operating range marked on the indicator); and the right engine turbine temperature indicator captured at 327 degrees C (also within the normal operating range marked on the indicator.) The on-scene investigators reported to the NTSB investigator-in-charge (IIC) that they found no evidence of an aircraft or engine malfunction at the accident site, and no evidence of inflight fire. The accident aircraft was equipped with a cockpit voice recorder (CVR.) The CVR was removed from the aircraft and sent to the CVR lab at the NTSB Engineering and Computer Services Division, Washington, DC, for readout. The attempt to read out the accident aircraft's CVR revealed that the CVR was inoperative at the time of the accident, and contained no data. The accident aircraft's engines were removed and shipped to the manufacturer, AlliedSignal Aerospace of Phoenix, Arizona. A teardown inspection of the left engine was subsequently conducted under FAA supervision at AlliedSignal's Services Repair and Overhaul Facility in Phoenix on July 17 and 18, 1997. In its report to the NTSB on the teardown examination (number 21-9792, dated November 7, 1997), AlliedSignal reported: "...The teardown and examination of the engine disclosed that the type and degree of damage was indicative of engine rotation and operation at the time of impact with the ground. No pre-existing conditions were found which would have prevented normal operation...." In a telephone conversation with the first officer on July 28, 1997, the first officer reiterated his written account of the accident sequence to the NTSB IIC. The first officer further stated that the V-speeds were calculated for the accident flight and written onto the TOLD card, but that on the accident flight, he had overlooked setting the airspeed indicator "bugs" with the takeoff V-speeds for the accident takeoff. He stated that the airspeed bugs thus were set to the landing speeds for the previous flight, approximately 11 knots below the correct takeoff V-speeds. (NOTE: The Normal Procedures section of the FAA-approved Learjet 35A/36A Flight Manual contains the steps "Takeoff Data (N1, V1, VR, V2, Takeoff Distance) - Computed and bugs set..." in the Before Starting Engines procedure, and "Takeoff Data (N1, V1, VR, V2) - Reviewed and Bugs Set" in the "Taxi and Before Takeoff" procedure. These steps are applicable both at the original departure point of a flight, and to through flights.) The first officer also stated to the NTSB IIC during this conversation that prior to the accident, there was no preflight discussion or briefing between the pilots regarding possible simulated emergencies. A Great Falls special weather observation at 1329 (approximately 15 minutes after the reported time of the accident) reported ## Aircraft - Registration: [N1AH](https://openairdocs.org/deregistered/N1AH-1997-11-22), registration cancelled 1997-11-22, S/N 398 (OpenAirDocs) - Reported make and model: Learjet 35A - Registry model: [Gates Learjet 35A](https://openairdocs.org/model/gates-learjet-35a) (registry code 5170602) (OpenAirDocs) - Category: Airplane - Serial number: 35-398 - Airframe hours: 8019 - Engines: Garrett TFE731-2-2B 3150 lbs thrust turbo fan - Damage: Substantial damage - Fire: On-Ground - Flight: Positioning, Part 91 - Operator: Professional Flight Crew Svcs, doing business as First Air Jet Charter - Registered owner: Agh Aviation Ltd. - Airworthiness certificate: Standard, Transport - Last inspection: AAIP, May 13, 1997, 13 hours before - Departed: GTF - Destination: DAL, DALLAS, TX - Flight plan: IFR - Airport: GTF, Great Falls Intl, runway 21, 10,502 × 150 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 37; airline transport, flight instructor; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 8,700 total, 2,000 in this make and model, 8,200 as pilot in command, 110 in the last 90 days, 40 in the last 30 days, 8 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 246° at 7 knots, gusting 19 - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 75 °F, dew point 39 °F - Altimeter: 30.00 inHg - Observed at: GTF ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 19970516010899A](https://openairdocs.org/incident/19970516010899A), May 16, 1997: Lear 35A, Great Falls, MT, Substantial damage. Aircraft lost control on takeoff and ran off runway. From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.