Accident Overview
On April 16, 2010, about 1906 Pacific daylight time, a Cessna 182, registration N5318B, collided with wires during a forced landing at El Cajon, California. The owner was operating the airplane under 14 Code of Federal Regulations Part 91. The commercial pilot, who also held a certified flight instructor certificate, and one passenger sustained minor injuries. The airplane sustained substantial damage from impact forces and a post-crash fire.
Flight Details
The local personal flight departed Gillespie Field in El Cajon at 1825. Visual meteorological conditions prevailed, and no flight plan was filed. Before departure, the pilot completed a thorough preflight. The airplane had more than half a tank of fuel in the left wing and just over a quarter tank in the right wing, which matched the fuel gauge indications.
After departure, the pilot was cleared westbound through Montgomery Field airspace at 2,500 feet. Near the coast, he began a shallow descent to remain under a cloud, turned southbound, and followed the coastline at 500 feet above ground level. He flew around the local area before heading back to Gillespie Field. He checked fuel quantity: the left tank indicated between one-quarter and one-half, and the right tank slightly below one-quarter. He believed he had sufficient fuel for the remainder of the flight.
The pilot transitioned eastbound through Montgomery airspace at 2,500 feet. Once clear, he contacted Gillespie air traffic control tower. He stated his intention to orbit the Mt. Helix area before landing. He pulled carburetor heat and descended to 2,000 feet, completing several shallow turns above his parents' house.
Engine Power Loss
During the second orbit, the pilot heard and felt the engine sputter, then go to idle. He immediately leveled the wings, turned toward the airport, and exercised the throttle while reporting inbound to the tower. When he did not get the expected engine rpm, he pulled carburetor heat again. He verified that both magnetos were on, the mixture was rich, the primer was in and locked, and the fuel selector was in the both position. He slowed to best glide speed and again exercised the throttle, noting a rise in manifold pressure but not rpm. He switched the fuel selector to the left tank only, then to the right tank only, but neither produced results.
Assessing his altitude and location, the pilot decided to request runway 35. The tower controller asked him to make a 360-degree turn, but he advised that he was unable and informed them of his situation.
Forced Landing
It soon became apparent that the airplane could not reach the airport. The pilot chose to land on North Johnson Road. He observed no cars but saw numerous power lines and telephone cables. He intended to clear one set of wires and quickly nose over to regain airspeed and get under the next set. However, he did not see two lines that crossed the road at his intended landing point. One cable caught the underside of the aft fuselage, ripping off the right end and trailing section of the horizontal stabilizer. The two poles holding the wires fell over, and the wire snapped. The pilot tried to maintain a nose-high attitude. The airplane impacted the ground at a 35-degree nose-down angle and skidded to a stop. After pulling his face away from the instrument panel, the pilot noticed fire at his feet. Both occupants exited through the left door and got away from the airplane, which became fully engulfed in flames a few minutes later.
Post-Accident Examination
The National Transportation Safety Board investigator-in-charge examined the engine. Detailed examination notes are in the public docket. No anomalies were found that would have precluded normal operation of the airframe or engine.
The FAA had published Special Airworthiness Information Bulletin (SAIB) CE-09-35 on June 30, 2009, regarding carburetor ice prevention. The SAIB noted that carburetor icing can occur at temperatures above freezing when there is visible moisture or high humidity. It states that vaporization of fuel combined with the venturi effect causes sudden cooling, allowing significant ice buildup within a fraction of a second. The SAIB includes a graph illustrating the probability of carburetor icing for various temperature and relative humidity conditions. The conditions encountered in this accident—ambient temperature 61 degrees Fahrenheit, dew point 50 degrees Fahrenheit, 68 percent relative humidity—were at the boundary of the areas for serious icing for glide power and cruise power.