NTSB Factual Report

HISTORY OF FLIGHT

On December 24, 1993, at 1806 Pacific standard time, an Aero Commander Lark 100A, N4042X, was destroyed during a collision with terrain while on a go-around attempt at the Chico, California, airport. Instrument meteorological conditions consisting of an obscured sky and zero ground visibility fog prevailed. No flight plan was filed for the operation; however, the pilot was operating on a night special VFR clearance from the Chico Air Traffic Control Tower (ATCT) at the time of the accident. The certificated private pilot sustained fatal injuries and the two passengers on board incurred serious injuries. The flight originated at Palo Alto, California, on the day of the accident at 1623 hours as a personal cross-country flight to Chico.

An examination was made of the air-to-ground communications tape recordings at the Chico ATCT and the transcripts of those recordings, which were obtained from the Federal Aviation Administration (FAA). From 1738 through the accident time, the local controller made several transmissions detailing the meteorological conditions on and around the airport. The transcripts are attached to this report.

The Chico Control Tower is located 1/4 mile from runway 13L/31R and 5/8 mile from the approach end of 13L/31R. The Chico Tower reported to the pilot of an inbound Cessna at 1741:34 that the airport was going IFR. The first special VFR clearance issued at 1751:05 on the evening of the accident was to a Cessna 182 inbound from the south. At that time, the weather was reported to be indefinite ceiling 300 feet, visibility 1 mile in fog. The pilot of the first aircraft stated that when he was established on the localizer he could see the runway lights and the fog movement. Upon touchdown, he went near zero zero in fog and could no longer see runway lights or the tower. He commented on the radio frequency that it was "getting very foggy." He said there was no response to his transmission.

At 1743:26, the controller transmitted to an aircraft in the control zone, "visibility is below 1/2 mile at this time from my vantage point." As the flight operations continued at the airport, the controller transmitted to another inbound VFR aircraft at 1754:12, "I'll need to know when you're down sir I have no visual contact with the runway." Several other similar radio exchanges are detailed in the transcripts.

In a land line call to the Redbluff Flight Service Station (FSS) at 1759:30, the controller reported, "Chico with a special {weather observation} for five past the hour...forecasting how about woxof (indefinite ceiling sky obscured zero visibility)." FAA Order 7110.65 contains agency directives to air traffic control personnel concerning the control of aircraft. Section 5 of Chapter 7 details procedures for the issuance of clearances for fixed wing special VFR operations in Class B and D airspace. Paragraph 7-46 concerns conditions where ground visibility is below 1 mile and states in part: "Treat requests for SVFR fixed wing operations as follows when the ground visibility is officially reported at an airport as less than one mile: a. Inform departing aircraft that ground visibility is less than one mile and a clearance cannot be issued... c. Inform arriving aircraft...that ground visibility is less than one mile and request the pilot to advise intentions."

At 1742:17, the pilot of the accident aircraft reported 17 miles south for landing and said, "Any chance of getting special vfr." The controller responded, "We will be ifr by the time you arrive...call me six to seven miles out." The pilot reported 6 1/2 miles south of the airport at 1750:11, and the controller informed the pilot, "you are number three in the request lineup for special vfr clearance...it appears that on the west side will get you the best visibility..."

At 1800:30, the controller cleared the accident aircraft (Lark 4042X) into the Chico airspace by issuing a special VFR clearance and then said, "cleared to land runway one three left report on the ground." The pilot reported at 1805:28 that he was "a little high I'm probably going to have to go around." The controller then approved the flight to make "right traffic."

The aircraft wreckage was subsequently located about 1 mile west of the Chico Airport after a passenger exited the wreckage and went for help. Search and rescue personnel reported that locating the wreckage was hampered by ground fog and darkness.

PILOT INFORMATION

The pilot held a private certificate with a rating for single- engine land airplanes. The pilot did not hold an instrument rating. According to records that were recovered during the investigation, he had accumulated about 1,559 hours of flight time. About 1309 hours were in the accident airplane. The pilot had documented 5.8 hours of simulated instrument/hood flight time, 5.5 hours during 1981 and 1982, and 0.3 hours on February 20, 1986. According to the pilot's logbook, the last biennial flight review was conducted on April 1, 1992. The pilot's last third-class flight physical was issued September 13, 1992, with the limitation that the pilot wear correcting lenses.

AIRPLANE INFORMATION

According to the airplane logbooks, the last documented annual inspection was performed on March 25, 1993, at a tachometer reading of 709.14 hours. The tachometer reading at the accident site was 833.87 hours.

The last documented static and altimeter tests (FAR 91.411) were performed on December 20, 1989. The last documented transponder test and inspection (FAR 91.413) was also performed on December 20, 1989.

METEOROLOGICAL INFORMATION

At 1759:30 hours, a special weather observation was relayed to the Red Bluff FSS by the local controller via land line telephone. The observation reported, indefinite ceiling zero, sky obscured, visibility zero, fog.

The pilots of several air taxi cargo flights which operated into and out of the Chico airport on the night of the accident were interviewed.

Ameriflight (AMF) 221 landed at Chico in VFR conditions at 1731 hours. The pilot reported 10 miles visibility on final approach to runway 13L. He also stated that he observed a fog bank to the northwest of the airport up against the foothills. At 1741, the pilot of AMF221 was taxiing out for departure and noted that the fog was moving south-southwest. The pilot requested a special VFR departure and was airborne at 1745. He stated that about half of the Chico airport traffic area was covered by fog with 2 mile visibility. The pilot stated that the bases of the fog south-southwest of runway 13 centerline was 500- to 800-feet agl and the fog bank ended 1/4 mile south-southwest of the extended runway 13L centerline.

Ameriflight 242 departed on an IFR flight plan at 1747:59. The pilot stated that at takeoff the approach end of runway 13L was still VFR. After rotation at 50 feet agl, the pilot said he ran into a wall of fog. Visibility decreased to 1/2 mile or less. At 100- to 200-feet agl, the pilot was on top of the ground fog and reported the observation to the tower. The pilot stated that: "the field quickly and surprisingly went IFR when a wall of ground fog moved over the field from the southeast. The tower reported visibility of one and one half was probably accurate, but did not adequately describe the weather as the visibility varied widely depending on the direction." At 1749:15, the pilot reported to the tower that the fog was about 100 feet thick.

Ameriflight 202 departed on a special VFR clearance at 1756:24. The pilot observed that the fog was no more than 100 feet deep and there were no bases to the fog. He stated that the visibility was decreasing rapidly at his departure time.

A Safety Board staff meteorologist conducted a weather study of the conditions in and around the Chico airport. The report of his study is attached to this report.

WRECKAGE AND IMPACT INFORMATION

According to an FAA inspector on scene, the airplane had collided with flat terrain with the left wing first. The wreckage path was reported to be 350 degrees magnetic.

The FAA did a postcrash examination of the airframe, the engine, and all related system components, and they reported no evidence of preimpact failure or malfunction.

MEDICAL AND PATHOLOGICAL INFORMATION

On December 28, 1993, the Butte County medical examiner performed an autopsy on the pilot.

Toxicological specimens were obtained from the pilot and were examined by the Federal Aviation Administration's Civil Aeromedical Institute in Oklahoma City, Oklahoma. The results were negative for carbon monoxide, cyanide, volatiles, and drugs.

ADDITIONAL INFORMATION

The wreckage was released to the insurance company representative on February 24, 1994.

NTSB Probable Cause

ISSUANCE OF AN IMPROPER (SPECIAL VFR) CLEARANCE BY THE TOWER CONTROLLER, WHILE THE VISIBILITY WAS LESS THAN ONE MILE, CONTINUED VFR FLIGHT BY THE PILOT INTO INSTRUMENT METEOROLOGICAL CONDITIONS (IMC), AND THE PILOT'S FAILURE TO MAINTAIN CONTROL OF THE AIRPLANE AFTER BECOMING SPATIALLY DISORIENTED. FACTORS RELATED TO THE ACCIDENT WERE: DARKNESS, FOG, FAILURE OF THE CONTROLLER TO ADVISE THE PILOT OF THE LATEST WEATHER INFORMATION, AND THE PILOT'S LACK OF INSTRUMENT EXPERIENCE.