# NTSB SEA08LA128: Moravan Zlin 50LX, N6660K, Modesto, CA, May 10, 2008 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: May 10, 2008, 13:00 local (20:00 UTC) - Place: Modesto, CA - Coordinates: 37.625556, -120.95417 - Nearby events: https://openairdocs.org/map.md?lat=37.6256&lon=-120.9542&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-aerobatics: Low altitude operation/event](https://openairdocs.org/ntsb-events/220) - Highest injury: Serious injuries - Injuries: 1 serious - Status: Completed, report December 24, 2008 - Report: Approved by Office Director - Parties: Federal Aviation Administration - NTSB case key (mKey): 67977 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA08LA128 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/67977/pdf - Page: https://openairdocs.org/ntsb/SEA08LA128 ## Probable cause The pilot failed to maintain clearance from terrain during a low-altitude maneuver at an airshow. Contributing to the accident was the task overload in the increased frequency congestion. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Performance/control parameters](https://openairdocs.org/ntsb-findings/01062000): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Moravana S Otrokovice ZLIN 50LX, 1 case](https://openairdocs.org/ntsb-findings/01062000/cases.md?model=5920211), [All aircraft, 1,269 cases](https://openairdocs.org/ntsb-findings/01062000/cases.md) - [Workload management: task overload](https://openairdocs.org/ntsb-findings/02064025): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Moravana S Otrokovice ZLIN 50LX, 1 case](https://openairdocs.org/ntsb-findings/02064025/cases.md?model=5920211), [All aircraft, 18 cases](https://openairdocs.org/ntsb-findings/02064025/cases.md) - [Action: incorrect action performance](https://openairdocs.org/ntsb-findings/02041015): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Moravana S Otrokovice ZLIN 50LX, 1 case](https://openairdocs.org/ntsb-findings/02041015/cases.md?model=5920211), [All aircraft, 1,386 cases](https://openairdocs.org/ntsb-findings/02041015/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering-aerobatics: Low altitude operation/event](https://openairdocs.org/ntsb-events/220) (defining event); cases with it: [Moravana S Otrokovice ZLIN 50LX, 1 case](https://openairdocs.org/ntsb-events/220/sequence.md?model=5920211), [All aircraft, 780 cases](https://openairdocs.org/ntsb-events/220/sequence.md) - [Maneuvering-low-alt flying: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Moravana S Otrokovice ZLIN 50LX, 1 case](https://openairdocs.org/ntsb-events/470/sequence.md?model=5920211), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The pilot was performing in an airshow that was conducted at a controlled airport serviced by airlines. Two Federal Aviation Administration (FAA) inspectors acting as the FAA monitors, witnessed the accident. Performances, as a rule, are timed so that they do not conflict with inbound and landing airline traffic. If there is a timing conflict, normally the show is temporarily stopped so as not to delay the airline traffic. During the accident pilot's performance, the pilot was transmitting directly to the crowd, as well as communicating with an on ground safety observer, the airshow waiver holder, and an air traffic control tower controller. The air traffic control tower controller advised the pilot to stop the performance due to an inbound arriving airliner and make a right base entry for landing. The pilot had completed a normal sequence and then requested to make one more pass and the tower controller approved the request. The pilot then added the additional maneuver as his final routine before exiting the performance box. The FAA inspector indicated that during the added maneuver, the right wing impacted the ground. The pilot stated that during the airshow briefing, he had requested a sterile frequency for maintaining communication with airshow and ground support staff, which he indicated was standard operating procedures at other airshows. The air traffic control tower personnel elected to have the airshow pilots monitoring and communicating on the same frequency as the tower controllers. The pilot stated that during the flight, he was interrupted numerous times by tower personnel and incoming aircraft, which prevented his ground safety observer from communicating with him and not only added to his workload, but affected his concentration during the maneuver. ## Factual narrative On May 10, 2008, at 1300 Pacific daylight time, a Moravan Zlin 50LX, N6660K, collided with terrain while performing at the Modesto Air Show, Modesto, California. The commercial pilot, who was also the registered owner of the airplane, was operating it under the provisions of 14 Code of Federal Regulations Part 91. The pilot sustained serious injuries, and the airplane was substantially damaged. Visual meteorological conditions prevailed, and no flight plan was filed. The flight departed about 1245. Two Federal Aviation Administration (FAA) inspectors acting as the FAA monitors, witnessed the accident. During the accident pilot's performance, the pilot was transmitting directly to the crowd, as well as communicating with an on ground safety observer, the airshow waiver holder, and an air traffic control tower controller. The pilot had completed a normal sequence and then added an additional maneuver. The FAA inspector indicated that during the added maneuver, the right wing impacted the ground. Additionally, the FAA inspector indicated that the airshow is conducted at a controlled field serviced by airlines. Performances, as a rule, are timed so that they do not conflict with inbound and landing airline traffic. If there is a timing conflict, normally the show is temporarily stopped so as not to delay the airline traffic. In the pilot's written statement, he indicated that during the airshow briefing, he and others had requested a sterile frequency for maintaining communication with airshow and ground support staff, which he indicated was standard operating procedures at other airshows. The air traffic control tower personnel elected to have the airshow pilots monitoring and communicating on the same frequency as the tower controllers. The pilot stated that during the flight, he was interrupted numerous times by tower personnel and incoming aircraft, which prevented his ground safety observer from communicating with him. He continued by stating that near the end of his routine, while performing rolls at a low altitude, he received, "...unanticipated, reckless, and urgent directions to immediately leave the airshow area in mid-maneuver." He advised the tower controller that he had too much energy to follow their instruction. He then stated that at a, "...critical point later in my maneuver, the tower then carelessly directed me on an urgent basis to go straight out of the airshow box. This combination of events, including but not necessarily limited to the mid-maneuver situation, the lack of a sterile frequency...and the directions from the tower...resulted in further disorienting me to a point that I hit the ground." The FAA accident coordinator transcribed the communication between the pilot, the airshow waiver holder, the safety observer, and the tower controller. The transcript showed that during the pilot's performance, an airliner contacted the tower to land. The airliner reported that they were 5 miles from the airport, and the airshowwaiver holder told the accident pilot that an airliner was 5 miles from the airport and that, "...this will be your last one." Then, the tower controller contacted the pilot and advised him to make a right base entry for landing on runway 28 right. The pilot requested to make one more pass and the tower controller approved the request. The pilot affirmed. The airliner then landed and was told to contact the ground controller. The tower was then contacted by ground operations requesting to cross a runway to the accident site. According to the Modesto airshow waiver holder, prior to the show all pilots are given a briefing from the airshow waiver holder, FAA personnel, and air traffic control tower personnel. During this meeting the frequency was discussed, and tower personnel elected to have the pilots on the tower frequency. According to the airshow waiver holder, during the accident flight, both he and the tower controller advised the accident pilot that an airliner was inbound to the airport. According to the waiver holder, the pilot requested with the tower controller to perform another pass and then collided with the ground during this maneuver. ## Aircraft - Registration: [N6660K](https://openairdocs.org/deregistered/N6660K-2013-11-22), registration cancelled 2013-11-22, S/N 0075, built 1996 (OpenAirDocs) - Reported make and model: Moravan Zlin 50LX - Registry model: [Moravana S Otrokovice ZLIN 50LX](https://openairdocs.org/model/moravana-s-otrokovice-zlin-50lx) (registry code 5920211) (OpenAirDocs) - Registry engine: [Amateur-built UNKNOWN ENG](https://openairdocs.org/engine/amateur-built-unknown-eng) (registry code 99999) (OpenAirDocs) - Category: Airplane - Serial number: 075 - Airframe hours: 1111 - Engines: Textron Lycoming IO-540 reciprocating - Damage: Substantial damage - Flight: Air race/show, Part 91 - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Condition, April 12, 2008, 8 hours before - Departed: KMOD, Modesto, CA - Destination: KMOD, Modesto, CA - Airport: KMOD, Modesto City-Cty Airport, runway 28R, 5,911 × 150 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 66; injuries: serious; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, without waivers/limitations; last flight review September 4, 2007; seat: single; flight hours: 4,000 total, 1,500 in this make and model, 30 in the last 90 days, 15 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 310° at 3 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 81 °F, dew point 43 °F - Altimeter: 29.97 inHg - Observed at: MOD ## 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 20080510836999A](https://openairdocs.org/incident/20080510836999A), May 10, 2008: Zlin ZLIN50LX, Modesto, CA, Destroyed. (-23)N6660K was finishing with the aerobatic performance and made a final pass from east to west along the show center line. The aircraft was observed… 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.