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On January 16, 2004, about 1415 Pacific standard time, a Cessna 180K, N61691, and a Beech 95-B55, N555RD, collided about 6 nautical miles west-southwest of Tehachapi, California. The Cessna was destroyed, and its pilot was fatally injured. The pilot held an airline transport pilot certificate, and he was a partial owner of the airplane, which was operated under the name of ABA Communications, LLC. The Beech was substantially damaged, and its owner-pilot received minor injuries. Visual meteorological conditions prevailed during the personal flights. At the time of the head-on midair collision, neither airplane was on a flight plan. Both flights were performed under the provisions of 14 CFR Part 91. The Cessna's flight originated at an undetermined time from Lancaster, California. The Beech's flight originated from Tehachapi, the pilot's home base airport, approximately 1412. The Federal Aviation Administration (FAA) was not providing any services to the pilots at the time of the accident.
The Cessna airplane's co-owner reported to the National Transportation Safety Board investigator that the accident pilot had initiated his flight from the General Wm. J. Fox Airfield (WJF). The pilot intended to fly the airplane for a few hours.
The pilot's route of flight from WJF to Bakersfield, California, was not determined. The FAA reported that at 1316, the Cessna pilot contacted the Bakersfield Terminal Radar Approach Control facility (TRACON) and requested practice instrument approaches to the Bakersfield Meadows Airport. The pilot received the requested clearance, and he performed practice instrument and missed approaches.
Subsequently, at 1355, the pilot requested a climb to visual meteorological conditions en route to WJF. At 1358, the pilot reported having reached visual conditions and canceled his instrument clearance.
At 1409, the pilot requested cancellation of the flight following services. The FAA controller acknowledged the request and approved the pilot to change frequencies to the WJF advisory frequency. There were no further radio communications to or from the Cessna pilot.
The Beech pilot provided the Safety Board investigator with oral and written statements regarding the accident flight. In pertinent part, the pilot stated that his airplane was equipped with a traffic alert system consisting, in part, of a Ryan International Traffic Collision Alerting Device (TCAD), model 9900BX, and a Garmin global positioning satellite receiver, model GNS 530. Integrated in the GNS 530 was the display for the Ryan TCAD.
The pilot indicated that this type of equipment had been in his airplane for about 1.5 years, and he was familiar with its operating protocols and functionality. The pilot stated that during the flight there were no indications of any mechanical malfunctions with the airplane engines, systems, or avionics.
According to the pilot, upon climbing through 5,000 feet mean sea level (msl) he established the airplane in a cruise climb configuration. The rate of climb was between 800 and 1,000 feet per minute, and the airspeed was about 140 knots. The range on the GNS 530 was set for 35 miles. Initially, no traffic was observed in his vicinity.
Then, he heard the words "traffic, traffic" in his headphone. The pilot reported that he recognized this voice sound as being a "traffic alert" signal instigated by activation of the Ryan TCAD. The position of the conflicting traffic was displayed on the GNS 530. In response to the alert signal, the pilot glanced at the display and observed a yellow dot in the 1 o'clock position, relative to his airplane. The pilot stated that the display of a yellow colored dot indicated that the traffic was in close proximity to his airplane.
In a written statement subsequently provided by the pilot, he reported that the first traffic alert he heard was for traffic at his 2 or 3 o'clock position. He searched to his right and did not observe traffic. Thereafter, upon again looking again at the GNS 530's display screen, he observed traffic in his 1 or 2 o'clock position and close to the airplane symbol. He began a turn to the left. The pilot looked again at his 1 to 2 o'clock area and did not see traffic.
The pilot stated that he could not recall what altitude value was displayed for the approaching airplane. But, he recalled the altitude was not "zero zero." He believes that it may have been plus or minus 100 or 200 feet, but he did not have a specific recollection. The pilot did not recall seeing the numeric altitude value change when he subsequently glanced at the GNS's display.
The pilot reported that the collision avoidance system had no provision for resolution of the alert warning. He indicated that, on previous flights, he had observed the display of a "ghost target." He indicated that initially when a ghost target is detected, it might move from the left side to the right side or be in various positions until it finally is permanently displayed. Because of his experience with the unit, he was initially uncertain whether the depicted yellow target was to the airplane's right or left side.
The pilot stated that after he saw the yellow target, he then "looked around," but did not see any approaching aircraft. He indicated that the accident occurred several seconds thereafter. Upon further questioning by the Safety Board investigator, the pilot reported that less than 1 minute elapsed between the time the collision alert system first activated and the time of the collision.
The pilot indicated that just before the impact he observed what he believed was the right landing gear of an approaching aircraft in his 12:30 position. The pilot ducked to the left instinctively and while ducking he heard the "boom" of impact. He thought that he may have initiated left bank input on the control yoke, but he was uncertain. He believes that the accident occurred only a moment after seeing the approaching aircraft's landing gear.
Following the collision the pilot looked up, observed his bodily injuries, and decided to immediately land while he had both physiological capability and control of his airplane. He was concerned about losing consciousness.
In the pilot's written statement he stated that he thought about calling Mayday, but made the decision not to use the radio but rather to "fly the plane, fly the plane, fly the plane."
Below and to the left of the airplane he observed an unfamiliar dirt surfaced airstrip (subsequently determined to be the PSK (private) airstrip). The pilot initiated a left-hand pattern approach to its runway and made the precautionary landing. The pilot indicated that throughout the entire approach and landing, power was available on both engines.
Regarding his flight controls, the pilot reported that he had no difficulty moving the ailerons, but upon application of rudder pressure he felt that the rudder's movement was "stiff." The pilot reported that he did not recall his actual landing. However, after the airplane rolled to a stop on the runway, rather than exiting the cockpit through the cabin door, he exited by stepping over the area where the door and window had been located. The pilot then walked away from the airplane and called 911 to report what had transpired and to seek assistance.
Two ground-based witnesses reported to the Safety Board investigator that they had observed both airplanes seconds prior to the collision. In summary, the witnesses reported that the larger (Beech) airplane was flying in a westerly direction and appeared to be cruising in level flight. The smaller (Cessna) airplane appeared to be cruising in an easterly direction and also appeared to be in level flight. Neither airplane appeared to change course or alter its wing level appearance prior to the collision. Following the collision, the Beech continued flying in a westerly direction. A portion of the Cessna (subsequently identified as its entire right wing) was found on a hillside near where the main wreckage was located.
Pilot of Cessna
The pilot held an airline transport pilot certificate with the following ratings: airplane single engine and multiengine land, commercial privileges glider. He also held a certified flight instructor (CFI) certificate with the following ratings: airplane single engine and multiengine, instrument airplane, and glider. The CFI certificate was last renewed in August 2002. Additionally, he held a mechanic certificate with the following ratings: airframe and powerplant, with inspection authorization.
The pilot's total flight time and time in the accident model of Cessna was about 5,276 and 365 hours, respectively. He completed a flight review in August 2002. He had flown the Cessna about 2 hours within 90 days of the accident.
Pilot of Beech
The pilot held a private pilot certificate with the following ratings: airplane single engine and multiengine land, single engine sea, and instrument airplane.
The pilot's total flight time and time in the accident model of Beech was about 2,500 and 1,100 hours, respectively. He completed a flight review in January 2003. He had flown the Beech about 34 hours within 90 days of the accident.
The Cessna has a Standard Normal FAA airworthiness certificate. Its maximum certificated gross weight, per supplemental type certificate SA649NW, is 3,190 pounds.
In part, the Cessna was equipped with a Garmin GNS 430 receiver, and a Garmin GTX 330 Mode S Transponder, with software version 3.03. The Mode S transponder provides altitude-reporting data and responds to inquiries from traffic alert and collision avoidance system-equipped aircraft.
High Desert Avionics, Lancaster, was the repair station that installed the Mode S transponder in the Cessna on May 15, 2003. The repair station's owner reported that the transponder's serial number was 84106982.
During 2004 and 2005, Garmin modified and/or upgraded the software for use in the transponder and issued a series of service bulletins. A problem had been detected with earlier software versions in which, under certain circumstances, an airplane may not be visible at certain ranges. Specifically, on August 27, 2004, Garmin issued a mandatory service bulletin requiring the installation of version 3.06 software on GTX 330 transponders. Garmin stated "the v3.06 software update supersedes all previous updates related to FAA Airworthiness Directive 2004-10-15, which addresses a potential air-to-air safety issue between GTX 330/330D-equipped aircraft and those installed with various TAS, TCAD and TCASI equipment."
The FAA superceded this directive with an updated directive, AD 2005-1-19. According to this AD, no software upgrade was required for GTX 330 Mode S transponders utilizing software version 3.03.
The Beech has a Standard Normal FAA airworthiness certificate. Its maximum certificated gross weight is 5,100 pounds.
In part, the Beech was equipped with the following avionics:
1. Ryan International Corporation TCAD processor, Model No. 9900BX, serial number 990803;
2. Ryan Lower "L" band TCAD antenna, serial number 1492;
3. Ryan Upper "L" band TCAD antenna, serial number 1492; and
4. Garmin GNS 530, serial number 78300950.
The Ryan TCAD is interfaced to the Garmin GNS 530. On August 15, 2002, the airplane's FAA approved flight manual was supplemented to reflect the equipment's installation and operation.
WJF is located about 28 nm southeast of the accident site. At 1356, WJF reported the following weather conditions: sky clear; wind from 070 degrees at 4 knots; 10 miles visibility; temperature/dew point of 17/-1 degrees Celsius.
Ground-based witnesses located within 0.4 miles of the accident site reported to the Safety Board investigator that they did not experience difficulty observing the airplanes. None reported obstructions to vision. Two witnesses reported seeing blue sky at the time of the accident.
The Beech pilot reported that he did not observe the Cessna until just prior to impact. During his initial climb he had unrestricted visibility. The sun was not in his eyes during the flight. About the time of the collision, the sky above his position was blue. Also, he noted the existence of a high overcast sky condition in the vicinity of the Cummings Valley.
The FAA reported that within minutes before and after the time of the accident, none of its facilities had transmitted or received any communications from the airplanes.
WRECKAGE AND IMPACT INFORMATION
From an examination of ground scar at the impact sites, the distribution of fragmented wreckage from both airplanes, and witness statements, the airplanes were found to have collided over the Cummings Valley, between 5.7 and 6.2 nm west-southwest (252 degrees, magnetic) of the Tehachapi Airport. The estimated coordinates for the midair collision are: 35 degrees 07.4 minutes north latitude by 118 degrees 33.7 minutes west longitude. The elevation of the ground at this location is about 4,000 feet msl.
Based upon the (1) Cessna's last recorded radar position and 5,400-foot altitude; (2) its ground speed; (3) the 1.4 nm distance between the radar position and the location where its landing gear was found; (4) the Beech pilot's statement that the collision occurred during his 800 to 1,000 feet per minute cruise climb; and (5) his recollection of being between 5,500 and 6,500 feet msl when the collision occurred, the Safety Board investigator estimated that the impact occurred between 5,500 and 6,000 feet msl.
Components that had separated from the Cessna principally consisted of the right landing gear assembly, the lower half of the right wing's lift strut, and the right wing with the attached upper half of the lift strut. These components were found within an estimated 0.5 nm-long path, over an easterly magnetic track of 103 degrees, about 4,000 feet msl.
The main wreckage was found about 0.3 nm farther east. The wreckage was observed on a hillside in an estimated 2-foot-deep impact crater and at ground level. The approximate elevation was 4,400 feet msl. The left wing and its entire intact lift strut were found with the main wreckage. There was no evidence of fire.
The Safety Board investigator's examination of components found separated from the Cessna revealed the following principal impact damage: (1) the right main landing gear tire and strut assembly were abraded; (2) the tire's sidewall was punctured, and Plexiglas fragments were inside the tire; (3) one end of the lower half of the right wing's lift strut was bent in an aft direction in the area where it had been severed from the upper half of the lift strut; (4) one end of the upper half of the right wing's lift strut was similarly bent in an aft direction, and this portion of the strut remained attached to the right wing that had broken from its respective airframe attachment fitting.
The Beech pilot landed at the nearest airstrip, about 2 nm from the impact site. Components that had separated from the Beech principally consisted of fragments from the roof, right door frame, and Plexiglas windscreen. These components were found within an estimated 180-foot-long path, over a westerly magnetic track of 296 degrees.
According to the Beech pilot, he was able to maintain control of his airplane through the approach and landing. Neither engine nor preimpact malfunctions to airframe components were reported.
The Safety Board investigator's examination of the Beech revealed the following principal impact damage: (1) the right side front windscreen was broken and was missing; (2) the roof was severed from the forward cockpit, in an aft direction, to the mid-portion of the fuselage; (3) the top of the vertical stabilizer was severed; and (4) the leading edge of the upper portion of the rudder was crushed in an aft direction.
MEDICAL AND PATHOLOGICAL INFORMATION
The pilot's last aviation medical certificate was issued in the first class in September 2003. The certificate bore the following limitations: "Must wear corrective lenses and possess glasses for near and intermediate vision." The pilot's height was 73 inches.
An autopsy was performed on the Cessna pilot by the Kern County, Coroner's Office, 1832 Flower Street, Bakersfield, California 93305.
The pilot's last aviation medical certificate was issued in the second class in September 2003. The certificate bore the following limitations: "Must wear corrective lenses." The pilot's height was 72 inches.
The FAA's Bioaeronautical Sciences Research Laboratory performed toxicological tests on specimens from both pilots. The laboratory manager reported finding no evidence of ethanol or any screened drugs.
TESTS AND RESEARCH
Radar Track Data.
Radar facilities surrounding the accident site supplied the Safety Board investigator with recorded radar data for the accident time and location. Track data corresponding to the Cessna was noted, but it terminated as the Cessna approached the mountainous terrain surrounding the accident site.
In summary, the Cessna was observed departing the Bakersfield area and proceeding in a southeasterly direction while climbing. About 1411, the Cessna, which was southwest of Tehachapi, changed course and commenced tracking in a northerly direction. Its average ground speed was about 135 knots. Throughout the remainder of its recorded flight its altitude remained between 5,300 and 5,600 feet as indicated by its transponder.
The Cessna turned right to a northeasterly track during the last few seconds of recorded flight. The last radar hit was at 1414:42. At this time the Cessna was at 33 degrees 07.283 minutes north latitude by 118 degrees 35.417 minutes west longitude. Its altitude was 5,400 feet. This location is about 1.4 nm west-southwest (251 degrees, magnetic) from the location where the airplane's separated right main landing gear assembly was found.
No radar data was found for the Beech. Its elevation was reportedly below the radar coverage area.
In-flight Collision Orientation.
During the wreckage examination, the Cessna's right main landing gear tire/wheel assembly was positioned in the Beech's front windscreen where the pilot reported the impact had occurred. The assembly was then moved in an aft direction and positioned in the severed portion of the Beech's roof. The Cessna's tire/wheel assembly filled the respective holes in the Beech's structure.
The approximate midspan location where the Cessna's right wing lift strut was found severed was compared to 3-view drawings of the Cessna. The Cessna drawings were compared and overlaid with similarly scaled drawings of the Beech. The two airplanes were positioned in such manner as to replicate the occurrence wherein the Cessna's right tire impacted the Beech's roof. When in this configuration, the Safety Board investigator noted that the Cessna's wing lift strut would touch (impact) the leading edge of the top of the Beech's vertical stabilizer.
Cessna Visual Angles, Forward Direction.
The co-owner of the Cessna reported to the Safety Board investigator that when piloting his airplane you have "pretty good forward visibility." When looking in a forward direction, "you can easily see the horizon."
According to data provided by the Cessna Aircraft Company in its "Pilot View Chart," a pilot in the left cockpit seat can see in a forward direction and downward at a 10-degree angle. This downward view is similar to the view obtainable in a Cessna 150 and a Cessna 172, which are 10 and 11 degrees, respectively.
Beech Visual Angles, Forward Direction.
The Safety Board investigator entered the cockpit of the accident Beech. No obstructions to vision were noted when looking in a forward or (estimated) 30-degree upward direction.
Avionics Tests, Cessna.
The Garmin GTX 330 Mode S Transponder was destroyed. It was not tested.
Avionics Tests, Beech.
Under FAA supervision, the aforementioned Garmin and Ryan avionics components associated with the Beech's traffic advisory system were removed from the airplane and were tested to ascertain their functionality. Ryan International Corporation's V.P. Engineering made the following statement following the tests: "The results of these tests show that the 9900BX processor and antennas were operating properly and that they complied with calibration standards. The tests also show that the 9900BX was able to correctly acquire traffic, issue audible traffic advisories, and to communicate the data to the GNS-530. The GNS-530 was shown to correctly display the received data. There are no Service Bulletins or Airworthiness Directives associated with the 9900BX."
Ryan TCAD Model 9900BX, Pilot's Operating Handbook Information.
In pertinent part, the handbook states "WARNING The Model 9900BX does not detect all aircraft. It is designed as a backup to the See and Avoid concept and the ATC Radar environment."
The Model 9900BX uses transponder replies to generate advisories about nearby intruders. The Model 9900BX provides range, bearing, and, for altitude reporting aircraft, relative altitude.
There are three advisory levels: Traffic Advisories (TA), Proximate Advisories (PA), and Other Traffic (OT). A Traffic Advisory is audibly announced. A TA is generated if the Model 9900BX detects that the current track of the intruder could result in a near miss or collision.
When an intruder is detected, the Model 9900BX generates an audible voice annunciation. The announced phrase is always preceded by a tone and then begins as "traffic." The clock position of the alert is given, and then the relative altitude of the intruder and range is announced. For example, a TA about an intruder directly to the left within two hundred feet elevation would generate [tone] "Traffic. 9 o'clock, same altitude, less than one mile."
Midair Collisions. See and Avoid Requirements and Human Performance.
The FAA's Advisory Circular 90-48C, entitled "Pilots' Role in Collision Avoidance" discusses the special attention and continuing action necessary on the part of all pilots to avoid the possibility of becoming involved in a midair conflict. The AC indicates that the Federal Aviation Regulations set forth the concept of "See and Avoid," and indicates that this concept requires that continuous vigilance shall be maintained at all times, by each person operating an aircraft. Pilots should remain constantly alert to all traffic movement within their field of vision to ensure detection of conflicting traffic. Also, the performance capabilities of many aircraft, in both speed and rates of climb/descent, result in high closure rates limiting the time available for detection, decision, and evasive action.
The physiological limitations of human vision and reaction time have been investigated by the Safety Board. The Board has commented that under certain conditions when flying clear of clouds, pilots that are approaching each other with little relative motion (head-on) may be marginally able (or unable) to see each other in time to implement an avoidance maneuver. [Reference NTSB report No. AAR-85/07, Midair Collision of Wings West Airlines Beech C-99 and Rockwell Commander 112TC.]
Mountains surround the area around the Tehachapi Airport. The pilot reported that he flew in a westerly direction over a valley during climb out. Wreckage from both airplanes was found in the valley.
On June 22, 2004, all recovered wreckage from the Cessna was released while in storage at the facilities of the airplane recovery agent, Aircraft Recovery Services, Littlerock, California. The owner's insurance agent, Claimtx Co, Fountain Hills, Arizona, was advised. No parts were retained.
On April 13, 2004, the Beech was released to its owner's insurance adjuster, in care of the airplane recovery agent, Aircraft Recovery Services. On June 22, 2004, all of the avionics components that had been removed from the Beech for testing were hand delivered to the proprietor of Aircraft Recovery Services. No parts were retained.