SEA08LA128

NTSB accident investigation · Moravan Zlin 50LX · Modesto, CA · May 10, 2008

Accident · Serious injuriesLimited investigationFinal report
Date
May 10, 2008, 13:00 local (20:00 UTC)
Place
Modesto, CA
Injuries
1 serious
Damage
Substantial damage
Phase of flight
Maneuvering
Aircraft
N6660KMoravan Zlin 50LX
Defining event
Maneuvering-aerobatics: Low altitude operation/event
Weather
Visual (VMC) · Day
Status
Completed · report December 24, 2008
Report
Approved by Office Director
Parties
Federal Aviation Administration
FAA report
20080510836999A
Case key
67977

From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.

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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 · 3

NTSB’s coded findings. Those marked are part of the probable cause; the rest are factors or other findings. Under each, the cases with the same finding.

Performance/control parametersAircraft › Aircraft oper/perf/capability · Not attained/maintainedMoravana S Otrokovice ZLIN 50LX: 1 caseAll aircraft: 1,269 casesProbable cause

Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event is the one that best describes the accident. Under each, the cases with the same event anywhere in their sequence.

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
Reported as
Moravan Zlin 50LX
Category
Airplane
Serial number
075
Airframe hours
1,111
Engine
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

Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.

Flight crew

As NTSB recorded them. NTSB leaves out names.

Role
Pilot
Age
66
Injuries
Serious
Certificate
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.