Beech Bonanza accident at North Hollywood, California, 17 Oct 1955

Accident narrative

**The crash of Beech Bonanza N 5825C**

On October 17, 1955, at 2214 Pacific standard time, a Beech Bonanza C-35 crashed into an apartment building on Magnolia Boulevard in North Hollywood, California. The pilot and eight residents of the building were fatally injured, and one resident was seriously injured. The building sustained major damage, and the aircraft was destroyed by the impact and subsequent fire.

**The flight**

At approximately 2100, the pilot, Joel W. Thorne, filed a Defense Visual Flight Rules (DVFR) flight plan from Lockheed Air Terminal in Burbank, California, to McCarran Field in Las Vegas, Nevada. He estimated a departure time of 2115 with no passengers and four hours of fuel for a flight requiring approximately one hour and 0 minutes. At the time, Lockheed Air Terminal reported a 700-foot overcast ceiling, visibility of two miles in smoke and haze, and overcast tops variable between 2,500 and 3,000 feet mean sea level. Another pilot advised Thorne of these conditions.

Thorne held a commercial pilot certificate but did not hold an instrument rating. On his most recent medical application, he reported 3,800 total flying hours, including 800 hours of actual instrument time. However, investigators were unable to find personal logbooks to substantiate this experience. An instructor who flew with Thorne after he purchased the aircraft in June 1955 testified that his flying was "very rusty" and showed little evidence of his claimed hours.

At the time of the accident, the Civil Aeronautics Administration (CAA) was processing a violation report against Thorne. Earlier in October, he had been involved in three incidents where he climbed through overcasts without clearance or an instrument rating. During one of these flights, he exhibited extreme difficulty understanding an instrument descent clearance, delaying local traffic for 45 minutes. He had been reprimanded by a CAA Safety Agent and advised to terminate instrument flights until he was properly certificated.

The aircraft was fully equipped for instrument and night flight. However, it was being operated with a 52-gallon nonstandard auxiliary fuel tank in the baggage compartment. The modification data had been submitted to the CAA, but final approval was pending, meaning the aircraft was flown contrary to regulations governing such alterations.

Earlier on the day of the accident, Thorne had departed Burbank but returned, reporting that his navigation lights, radio, and newly installed rotating anticollision lights had failed. Maintenance personnel determined an inadequate circuit breaker had caused the light failure. Thorne insisted the rotating lights be repositioned, with one mounted on top of the fuselage and the other on the bottom. Because the bottom light was inverted, the resulting flashes moved in opposite directions. The work was completed that day without an electrical analysis or a flight test.

**Sequence of events**

At 2159, Thorne radioed the Burbank Tower for taxi and takeoff instructions. When asked if he was flying under Instrument Flight Rules or climbing to on top, Thorne replied he wanted a clearance to climb westbound to on top. The controller cleared the flight for a 260-degree departure, instructing the pilot to make a right turn, climb on a magnetic heading of 260 degrees to on top, and report on top.

The takeoff at 2208 appeared normal to tower personnel, who noted the aircraft's navigation and two anticollision lights were on. The Bonanza was last seen turning right and climbing toward the overcast. There were no further radio contacts.

Shortly after, the tower received telephone calls from residents reporting an aircraft flying very low and appearing to be in trouble or stunting.

Witnesses on the ground helped reconstruct the flight path. An aircraft mechanic saw the Bonanza enter the overcast, after which the engine sound grew louder, giving the impression of a rapid descent and left turn. The aircraft emerged from the overcast at high speed, diving steeply and turning left. The nose jerked up sharply as the turn continued, and the aircraft disappeared back into the overcast in a steep climb. This witness noted the anticollision lights were on.

A second witness, a pilot, saw the aircraft pass closely three times in a circular path. He observed it climb into and dive out of the overcast several times, noting erratic movements that indicated difficulty with lateral and longitudinal control. The engine sounded uninterrupted and at high power, but its pitch increased and decreased with the aircraft's vertical oscillations. This witness, and all subsequent witnesses, observed that the anticollision lights were off.

Witnesses near the accident site stated the aircraft dived out of the overcast at an estimated 65- to 75-degree angle on a southeast heading, turning rapidly to the right. As it reached a southwest heading, it pulled up sharply. Several large components separated from the aircraft, and the main structure rolled violently to the right before plunging into the apartment roof.

**What the investigation found**

Wreckage distribution confirmed the aircraft sustained an inflight structural failure. Major portions of the right wing, right flap, right aileron, and the empennage were found up to several hundred yards northeast of the main wreckage. The right wing failed in upward bending from loads exceeding the structure's strength. The right aileron and flap were torn from the wing, with evidence showing the aileron was positioned well past its normal down travel before separation. The tail sections failed at the spar-to-fuselage attachments, indicating violent right rotation.

Laboratory examinations of the metal found no evidence of fatigue failure. A review of the design data showed the aircraft met or exceeded the minimum strength requirements for its category. The engine and propeller were examined, and investigators found no evidence of powerplant malfunction or failure. The landing gear and flaps were retracted. The Board considered the possible use or failure of the aircraft's auto-pilot, but complete destruction of the components precluded any determination.

To understand the effect of the relocated lights, Board investigators conducted flight tests in an overcast using a Bonanza with nearly identically mounted beacons. The tests revealed that the opposite rotation and brilliance of the lights caused the clouds to appear to move in, out, up, and down. The Board found this induced immediate and serious vertigo, requiring the highest degree of skill to maintain instrument control.

The Board believed that Thorne lost control of the aircraft, resulting in a characteristic descending spiral. The Board stated this loss of control was probably induced by vertigo, leading the pilot to follow sensory indications rather than his flight instruments. The Board noted that the initial vertigo was likely the result of the effect produced by the rotating beacons, compounded by the pilot's fatigued condition—witnesses noted he had slept little over the weekend while attending a birthday party and had spent Monday overseeing the light relocation.

The Board believed Thorne was unable to recover full control, flying alternately under visual and instrument conditions in panic and desperation, before an abrupt turning pull-up caused the structural failure.

During the hearing, CAA officials expressed dissatisfaction with the regulations governing flights within a control zone, noting that the rules lacked sufficient specificity to prevent pilots on VFR clearances from climbing through overcasts.

**Probable cause**

The Board determined that the probable cause of this accident was "the pilot's loss of control during which the design strength of the aircraft was exceeded causing structural failure. Vertigo, and the pilot's inability to take corrective action, were contributing factors."