1.1 History of the Flight

On December 23, 2005, at 1520 Pacific standard time, a Beech 36, N5942S, collided with hilly terrain 9 nautical miles east of the Livermore Municipal Airport, Livermore, California. The pilot was operating the airplane, which was registered to a private company, under the provisions of 14 CFR Part 91. The private pilot and passenger sustained fatal injuries. The airplane sustained substantial damage. Instrument meteorological conditions prevailed and the pilot requested and received a pop-up instrument flight rules (IFR) clearance about 1500. The flight originated from Santa Barbara Municipal Airport, Santa Barbara, California, at 1342, and was destined for Livermore.

1.1.1 Air Traffic Control History and Radar Information

Information obtained from Lockheed Martin Services, Inc. indicated that the pilot received an abbreviated weather briefing at 1002 from the Prescott Flight Service Station (FSS). After departing Santa Barbara, the pilot requested an additional abbreviated weather briefing via Flight Watch at 1439. The specialist advised the pilot that he should plan on an IFR approach to very low conditions at Livermore.

About 1500, the pilot requested an IFR clearance into the Livermore airport from Oakland Air Route Traffic Control Center (ZOA). The center controller issued the clearance and handed the aircraft off to the Northern California Terminal Radar Approach Control (NCT).

The pilot's first contact with NCT occurred at 1441, when the ZOA sector 10 controller contacted the NCT Morgan sector controller to coordinate an IFR clearance to Livermore. After some discussion, the controllers agreed that ZOA sector 10 would clear N5942S to Livermore via direct to Manteca vhf omni-directional range (VOR) at 8,000 feet. At 1443, the pilot contacted the Morgan controller and reported level at 8,000 feet. The controller acknowledged and issued the Salinas altimeter setting. The Morgan controller then advised the pilot that automatic terminal information service (ATIS) information "Uniform" was current at Livermore, showing wind 190 degrees at 4 knots, visibility 3 miles in mist, ceiling 600 feet overcast, temperature 60 degrees Fahrenheit, altimeter 30.23 inches of Mercury, and that the instrument landing system (ILS) approach to runway 25R was in use. The pilot acknowledged.

At 1448, N5942S was transferred to the NCT Castle sector. The pilot checked in and reported, "…level at 8,000." The controller asked the pilot to advise when he had information "Uniform" and the pilot replied that he had it.

At 1459, the pilot contacted the NCT Sunol sector, again reporting level at 8,000 feet. The controller advised the pilot of N5942S that information "Victor" was current at Livermore, and asked if the pilot had it. The pilot responded negative, and that he had information "Uniform." The controller provided the "Victor" weather information, reporting that Livermore was indicating wind calm, visibility 3 miles in mist, ceiling 600 feet overcast, altimeter 30.22 inches of Mercury, ILS runway 25R approach in use. The pilot acknowledged. At 1506, the pilot was instructed to contact NCT on 123.85, the Tracy sector frequency.

At 1507, the pilot contacted the Tracy sector and reported level at 8,000 feet. The controller acknowledged. At 1510, N5942S was cleared to descend to 7,000 feet and the pilot acknowledged. At 1511, the controller instructed the pilot of N5942S to turn left, heading 280 degrees, to join the localizer and report established. The pilot read back the heading. At 1513, the controller cleared N5942S to descend to 4,000 feet and the pilot acknowledged. At 1514:28, the controller again cleared N5942S to 4,000 feet and the pilot acknowledged. At 1514:35, the Tracy controller transmitted, "November 42S is one-zero miles from FOOTO, fly heading 280, cross FOOTO at 4,000, cleared ILS runway 25R approach." The pilot responded, "Cleared at 4,000, cleared for the approach." At 1515, the controller asked the pilot to verify that he had information "Victor" at Livermore and the pilot responded that he did. At 1517, the controller issued a traffic advisory to N5942S for an aircraft that was eastbound at 12 o'clock and 7 miles, altitude indicating 5,400 feet. The pilot responded that he was looking. At 1519:58 the controller transmitted, "N42S radar service terminated, contact Livermore tower 118.1, traffic no factor." The pilot acknowledged.

At 1520:07, the pilot contacted the Livermore tower and was cleared to land. The pilot's readback was unintelligible. There were no further transmissions from the airplane. At 1524:36, the local control (LC) controller made the first of four unsuccessful attempts to contact N5942S. At 1525:37, the controller advised the NCT Tracy sector that he had lost radio and radar contact with N5942S. Following that call, the controller made two more attempts to contact the aircraft with no response.

The ATCT personnel notified search and rescue personnel of a possible downed airplane and their reception of an electronic locator transmitter at 1529. The wreckage was located at 1800 at an elevation of 1,400 feet msl.

Radar data for the accident flight was reviewed by an NTSB air traffic control specialist. One track was consistent with the airplane's route of flight and identified by the airplane's discrete transponder code of 2040. N5942S was established at a mode C derived altitude of 8,100 feet and was cleared to descend to 7,000 feet. Radar data showed the target N5942S descended to 7,200 feet. At 1514, N5942S was cleared to descend to 4,000 feet and the descent of the identified target continued until impact with terrain. The radar data indicated that the target maintained a descent rate of about 1,100 feet per minute during the last minute of flight at a radar derived ground speed of approximately 112 knots.

During the approach into Livermore, the pilot was cleared to cross FOOTO intersection at 4,000 feet mean sea level (msl). Instead, radar targets indicated that the airplane crossed FOOTO at 3,300 feet msl at 1519:22 while established on the localizer course. At 1520:07, the pilot contacted Livermore ATCT and was cleared to land by the controller at 1520:11. At 1520:16, the last transmission was received from the airplane. The last radar target for the airplane was at 1521:08 at 1,600 feet msl, approximately 9 miles east of Livermore airport.

1.2 Personnel Information

1.2.1 Pilot Information

The pilot held a private pilot certificate with an instrument rating. The pilot's most recent third-class medical certificate was issued in July of 2004. It held the limitations that required the pilot to wear corrective lenses.

The pilot's personal flight time logbooks were not located. On the pilot's last medical certification application, he noted a total flight time of 1,200 hours.

An airplane logbook, that served as a record of the flights taken in the airplane, was recovered from the accident site. The logbook showed that the pilot had accrued approximately 88 hours since November of 2003 (the date of his first entry in the logbook). In 2004 he logged approximately 62 flight hours and in 2005 he logged approximately 20 flight hours. The last entry from the pilot was dated for a time period from November 23 through 27, 2005.

1.3 Aircraft Information

1.3.1 General Aircraft History

The airplane was manufactured in 1968 and was powered by a Continental IO-520-BA engine equipped with a two-bladed McCauley propeller, model 2A36C23. On August 4, 2005, the airplane underwent an annual inspection at a total airframe time of 8,358 hours. At the time of the accident, the airplane had accrued 8,395 hours. The engine had accrued 1,415 hours since major overhaul and the propeller accrued 1,415 hours since overhaul. The pitot static system and transponder check was completed on August 3, 2005 (the logbook entry was incorrectly dated August 3, 2007).

The onboard logbook for the airplane noted that an ILS approach was flown on August 12, 2005. The last flight prior to the accident flight was logged on December 15, 2005, ending at a tachometer time of 64.3. Co-owners of the airplane flew both of these flights.

1.3.2 Fueling

The airplane was topped off with 100 low lead (LL) fuel on December 23 (the day of the accident) at Santa Barbara, California.

1.4 Meteorological Information

The automated weather surface observation system (METAR) for Livermore reported the following at 1453: winds calm; visibility 3 miles with mist; ceiling 600 feet overcast, temperature 61 degrees Fahrenheit; dewpoint 57 degrees Fahrenheit; altimeter 30.22 inches of Mercury.

Geostationary Operational Environmental Satellite (GOES)-10 data for 1515 was reviewed and showed that there were clouds in the accident area. The GOES-10 infrared image showed a radiative temperature of about 37 degrees Fahrenheit. Comparing this data with the Oakland, California, upper air data for December 23 at 1600, this temperature resulted in cloud tops of about 12,000 feet.

1.5 Aids to Navigation and Communications

The pilot was conducting the instrument landing system (ILS) approach to runway 25R. FAA operational check of the ILS revealed no operational anomalies during the accident time frame. The ILS approach chart for runway 25R indicated that the final approach course was 225 degrees, and the compass locator at the outer marker (LOM) was 6.1 nautical miles from the runway. The crossing altitude over the outer marker was 2,409 feet msl. The approach chart noted that an automatic direction finder (ADF) was required and autopilot coupled approaches were not authorized below 1,700 feet.

The pilot was in contact with the Livermore ATCT when the accident occurred.

1.6 Wreckage and Impact Information

The National Transportation Safety Board investigator, the FAA accident coordinator, and a representative from Raytheon Aircraft Company, a party to the investigation, responded to the accident scene on December 24, 2005.

The airplane came to rest on hilly, grass-covered terrain used for cattle pasture. There was no evidence of fire. The initial impact point at 1,400 feet msl, was on a 20-degree slope; three separate holes, the approximate distance between the landing gear of the airplane were present in the soft, muddy soil. Just above these three holes was a large area of disrupted and churned soil, and the step of the airplane, normally located just aft of the right wing, was on the top surface of the soil. To the immediate left and right of this large disrupted area there were two rectangular shapes imprinted into the earth similar in shape and size to the leading edges of the wings. The nose gear was near this impact area. From this point, the debris path continued upslope in the agitated soil where the propeller hub, with one blade still attached, and the bottom strobe light were identified. The blade was bent slightly aft at the tip. Moving up the terrain on a magnetic heading of 258 degrees, the soil was less disrupted, although the grass was bent uphill and various cockpit components, the upper engine cowling, and the main landing gear, marked the wreckage path. The main wreckage came to rest 168 feet from the initial impact point and was at an approximate altitude of 1,467 feet mean sea level.

The fuselage structure of the airplane was compressed downward from the cockpit area aft to the baggage area. At this point, the fuselage was circumferentially buckled and bent forward. The elevator and rudder control cable continuity was obtained from the empennage to the carry through structure. Cable continuity from the right aileron to the carry through structure was confirmed. Full travel of the left aileron cable was restricted due to a pinch of the cable within the deformed wing structure. The left and right elevator trim actuators were measured at 1 10/16 inches and 1 7/16 inches, respectively. Manual actuation of the elevator trim cable showed associated movement to the actuator screws. According to the airframe representative, the left flap actuator measurement indicated that the left flap was retracted. Due to the deformity of the structure from the main landing gear struts pulling aft through the wing during the impact sequence, an accurate measurement for the right flap actuator was not obtained.

The separated propeller blade was located about 500 feet forward and slightly north of the main wreckage several months following the accident. The blade was twisted and gouged outboard near the tip.

1.7 Medical and Pathological Information

The Alameda County Sheriff's Office performed autopsies on the pilot and passenger. Both deaths were attributed to injuries sustained during the accident sequence. The Federal Aviation Administration Bioaeronautical Research Laboratory completed toxicological testing on specimens of the pilot and passenger. The results were negative for carbon monoxide, cyanide, volatiles, and all tested drugs (no volatile or drug testing were performed on the passenger).

1.8 Tests and Research

On January 10, 2006, the Safety Board investigator, and representatives from Teledyne Continental Motors and Raytheon Aircraft Company, further examined the wreckage at Plain Parts, located in Pleasant Grove, California.

1.8.1 Airframe

The control cables extending up to the rudder pedals and the control yoke were uncovered in the crushed and deformed forward fuselage. Access to the rudder and elevator controls was obtained from the interior of the fuselage and manual actuation was obtained. The rudder pedal crossover tube was fractured in the center section of the fuselage so movement was obtained to the left rudder pedals only. To gain access to the aileron control cables, the nose of the airplane was elevated and investigators were able to actuate the cables from that vantage point. Movement was obtained throughout all of the control systems.

The static and pitot systems were traced throughout the airplane. The static line was uncovered from the rear ports, along the left side of the fuselage, up to the cockpit instrumentation. Visual examination of the static lines to the instrumentation showed that they were free from obstruction. Investigators blew air into the static line connection based at the left lower cockpit. Air was transferred through the line to the right port, left port, and autopilot port, respectively.

The static lines were traced from the static air source to the instrumentation. A line leading from the altimeter to the vertical speed indicator (VSI) was fractured at its plastic fitting. The VSI was destroyed during the impact sequence. A t-fitting from the mode-C encoder was also severed but its adjoining part was identified behind the instrument panel and a tape identification tag showed that the adjoining part was a static test line. The test line was sealed. The other end of the t-fitting connected by design, to a line from the altimeter. The line from the altimeter fit over the tube on the mode-C encoder.

The pitot air line was traced from the cockpit instrumentation, outboard to the wing where the line had been cut during recovery. Investigators blew air through this line at an attach point in the lower cockpit and airflow was evident. Investigators located the remaining line which led to the pitot tube mounting point on the left wing and airflow was successful. The pitot tube had been severed from the wing during the accident sequence but was unobstructed.

The alternate air source lever was found in the closed (OFF) position.

1.8.2 Engine

The Teledyne Continental Motors IO-520-BA engine was detached from the wreckage, slung from a hoist, and examined. The propeller had separated from the crankshaft and only residual oil was present in the engine during the examination. Thumb compression was obtained on all six cylinders and the magneto leads produced spark in the appropriate firing order for the engine. Rotation was observed from the rear of the engine at the accessory case.

The top spark plugs were removed from the engine and showed similar wear and coloration signatures. When compared to a Champion Aviation Check-A-Plug chart, the coloration and wear was consistent with normal operation. Sound Spectrum Study

The analog recordings of air traffic control communications were sent to the NTSB Office of Research and Engineering for review. The sound signatures that were identified during the various radio transmissions were converted to propeller rotating speed in revolutions per minute (RPM). The following RPMs were noted:

1444:00 2,650 RPM
1449:00 2,600 RPM
1459:14 2,670 RPM
1507:04 2,650 RPM
1510:46 2,650 RPM
1513:28 2,625 RPM
1514:40 2,620 RPM
1513:03 2,603 RPM
1517:04 2,560 RPM
1520:02 2,560 RPM
1520:15 2,480 RPM

The last radio transmission at 1520:15 was approximately 1 second long and contained a garbled, unintelligible male voice. No airplane related alarms or horns were discernable in any of the radio transmissions.

1.8.3 Altimeter

The Aerosonic altimeter was examined at Aerosonic Corporation on April 19, 2006, by the NTSB investigator and the Director of Quality Improvement for Aerosonic. The altimeter (PN 101720-01999, SN 15-0761) was manufactured in August of 1994. The altimeter is a standard design and operates as such. As the aneroids expand, the rotating shaft rotates and is activated through a pin connection, moving the sector gear. When the sector gear moves, this moves the pinion on the intermediate gear assembly, which engages with the handstaff gears inside of the top plate. These top plate gears actuate the 10,000 and 1,000-foot pointers. The 100-foot pointer is shaft driven directly off of the mechanism assembly.

The static lines were still attached with a tee fitting on the back of the altimeter. The fitting and lines were removed. The static lines were sealed off using a series of rubber hoses connected in a loop and attached to an Air Data Calibration Test Set to test for leaks from the altimeter attachment fitting. Over a time period of 1 minute at a pressure of 7,000 feet, approximately 3 feet were lost.

The knob was removed and the bezel screws were unscrewed to facilitate removal of the bezel. All of the bezel screws were tight. Due to impact damage, the leak test was not performed on the altimeter. The glass lens was intact and sealed tightly to the altimeter casing.

The altimeter was equipped with three pointers: each one representing 100-foot, 1,000-foot, and 10,000-foot increments. The 100-foot point is driven by the mechanism assembly and remained connected. The 1,000 and 10,000-foot pointers attach at the top plate through gearing. Both of these pointers were smashed forward against the 100-foot pointer and the hub that the 100-foot pointer shaft mates to was bent toward the 3-o'clock position.

After the pointers were removed, the control knob was reattached and the barometric dial functioned in rotation when manually actuated with the control knob. The aneroids were placed on a test bench and functionally tested to 50,000 feet. The results were within the parameters as specified by the manufacturer.

The altimeter components were sent to the NTSB Materials laboratory for further examination. Altimeter Metallurgical Examination

The metallurgist examined the altimeter components. All direction references were made with components in their installed location within the airplane, with the face of the altimeter located aft.

The order of needle assembly from forward to aft was the faceplate, 10,000-foot needle, 1,000-foot needle, and 100-foot needle. All needles are attached to their respective shafts by an interference (press) fit. Markings were observed on several areas of the faceplate.

A circumferentially oriented linear mark was observed between 4.0 and 4.2 on the faceplate. The location of the mark corresponded with the approximate radial position of the 100-foot needle tip.

Several markings were observed on the 10,000-foot needle face, with the most apparent markings at 7.5 (75,000 feet). Observed markings were noted with the 1,000-foot pointer in the 1.0 (1,000 feet) position, and the 100-foot pointer in the 4.0 (400 feet) position.

1.8.4 Instrument Exam

The airplane was equipped, in part, with a KC 290 mode controller, KC 295 flight computer, KI-203 VOR/LOC converter, KI-525A pictorial navigation indicator, KI 256 flight command indicator, and KA 285 annunciator panel. The instruments were examined at Honeywell under the supervision of an FAA inspector. No operational anomalies were noted.

Loose within the wreckage, investigators located a handheld Garmin 196. The unit was brought to Garmin by an FAA inspector for download. According to the Garmin specialist, due to the damage sustained during the impact, no data was retrieved from the unit.

1.8.5 Air Traffic Control (ATC) Group

The ATC group convened on January 5, 2006, at the NCT. The NTSB ATC group chairman, and representatives from the FAA and the National Air Traffic Controllers Association, a party to the investigation, were present.

Recorded radar data for this accident was obtained from the NCT airport surveillance radar (ASR-11) located near Stockton, California, which was the radar site being used by the Tracy controllers at the time of the accident. The radar provided continuous targets for N5942S throughout the descent and nearly to impact.

NCT is equipped with minimum safe altitude warning (MSAW) software that is intended to alert controllers when an aircraft is, or is predicted to be, in unsafe proximity to terrain or obstructions. Radar data indicated that N5942S was beneath the ILS glideslope from before FOOTO intersection until the point of impact, and recorded MSAW data indicated that the system generated an alert from 1520:50 (approximately 1 minute after the airplane was handed off from the en route controller to the control tower controller) until impact at approximately 1521:13. This alert would have caused both a blinking "LA" above the data block for N5942S and an aural alarm at the Tracy sector. A tone similar to an MSAW aural alarm can be heard in the background of transmissions made by the Tracy controller to Mooney N15060, an uninvolved nearby aircraft, around the time of the accident.

Examination of MSAW adaptation data at NCT showed that Livermore tower becomes eligible to receive aural MSAW alarms when aircraft are operating within 10 miles of the airport reference point. At the time the alert activated, N5942S was approximately 9.2 miles from the airport reference point. Therefore, the Livermore local controller should have received both visual and aural alerts on N5942S when MSAW alarmed.

Recorded ARTS data indicated that aural alarm messages were sent to both Tracy and the LVK ATCT tower radar display at 1520:44. When interviewed, the Livermore controllers present in the cab at the time of the accident both stated that the aural alarm did not activate in response to this alert. According to anecdotal information provided by the Livermore air traffic manager, a "couple of weeks back" another MSAW alert occurred that was visual only, with no aural alarm. There was reportedly an unidentified FAA technician in the tower cab at the time, and she agreed to investigate the apparent anomaly. The FAA and NATCA were both asked to attempt to identify anyone who could substantiate the account and provide enough information to document the event, but have not been able to do so. However, because of this report, NCT and LVK ATCT both implemented a logging requirement to attempt to document any similar occurrences. According to FAA's Western Regional Terminal Service Unit, there have been no similar incidents logged since this accident.

1.9 Additional Information

1.9.1 Air Traffic Control Procedures

FAA Order 7110.65, "Air Traffic Control", provides instructions to controllers about how to respond to apparent hazards to aircraft. Paragraph 2-1-6, "Safety Alert," states, in part:

Issue a safety alert to an aircraft if you are aware the aircraft is in a position/altitude which, in your judgment, places it in unsafe proximity to terrain, obstructions, or other aircraft. Once the pilot informs you action is being taken to resolve the situation, you may discontinue the issuance of further alerts. Do not assume that because someone else has responsibility for the aircraft that the unsafe situation has been observed and the safety alert issued; inform the appropriate controller.

If a TRACON has given control of an aircraft to one of its remote towers, and the tower has aural and visual MSAW alert capability, the TRACON does not have to inform the tower controller if an alert is observed for that aircraft when it is within the remote tower's aural alarm area.

1. The issuance of a safety alert is a first priority (see para 2-1-2, Duty Priority) once the controller observes and recognizes a situation of unsafe aircraft proximity to terrain, obstacles, or other aircraft. Conditions, such as workload, traffic volume, the quality/limitations of the radar system, and the available lead time to react are factors in determining whether it is reasonable for the controller to observe and recognize such situations. While a controller cannot see immediately the development of every situation where a safety alert must be issued, the controller must remain vigilant for such situations and issue a safety alert when the situation is recognized.

2. Recognition of situations of unsafe proximity may result from MSAW/E-MSAW [en route minimum safe altitude warning]/LAAS [inhibiting low altitude alert system], automatic altitude readouts, Conflict/Mode C Intruder Alert, observations on a PAR [precision approach radar] scope, or pilot reports.

3. Once the alert is issued, it is solely the pilot's prerogative to determine what course of action, if any, will be taken.
a. Terrain/Obstruction Alert. Immediately issue/initiate an alert to an aircraft if you are aware the aircraft is at an altitude which, in your judgment, places it in unsafe proximity to terrain/obstructions. Issue the alert as follows:
(Identification) LOW ALTITUDE ALERT (call sign), CHECK YOUR ALTITUDE IMMEDIATELY, THE (as appropriate) MEA/MVA/MOCA/MIA IN YOUR AREA IS (altitude), or if an aircraft is past the final approach fix (non-precision approach), or the outer marker, of the fix used in lieu of the outer marker (precision approach), and, if known, issue THE (as appropriate) MDA/DH IS (altitude).

1.9.1 Wreckage Release

The NTSB investigator released the wreckage to the owner's representative. No parts or pieces were retained by the NTSB.

**This report was modified on May 25, 2007.**

Use your browsers 'back' function to return to synopsis
Return to Query Page