History of Flight
On August 29, 2011, at approximately 1427 Pacific daylight time, a Cessna 172M, registration N5155Q, impacted a tree and the side of a private residence about 0.2 miles west of the departure end of runway 21 at Santa Monica Municipal Airport (SMO), Santa Monica, California. The accident occurred during a go-around maneuver issued by a Federal Aviation Administration (FAA) air traffic control tower controller after the pilot's high and fast approach to the runway. The airplane was substantially damaged; the engine and instrument panel were displaced upward and aft, impinging on the cockpit space. The student pilot was seriously injured. The home was unoccupied at the time, but two of three painters working outside sustained minor injuries. The student pilot had rented the airplane from Justice Aviation for a planned solo instructional cross-country flight to Santa Barbara, California. The flight was conducted under 14 CFR Part 91 in visual meteorological conditions; no flight plan was filed. The airplane departed SMO at about 1423.
The student pilot reported that after takeoff, the airspeed indicator malfunctioned: the needle increased suddenly then dropped to zero. He believed the airplane was flying over 60 mph in a climb attitude. At 1423:38, he informed the controller of the failure and requested to return. The controller cleared him to land on runway 21. The student climbed into the traffic pattern but kept the airplane closer to the runway than normal, resulting in a higher-than-normal approach. He partially extended flaps but was high crossing the threshold. As the airplane approached the last quarter of the runway, about one wingspan above the surface, the controller directed a go-around at 1426:36. The pilot acknowledged, raised flaps, and applied full throttle. He saw power lines and maneuvered to avoid them.
Personnel Information
The student pilot held a first-class medical and student pilot certificate issued on December 16, 2010. He had about 48 total flight hours, all in the accident make/model, with about 13 hours as pilot-in-command. His certified flight instructor (CFI) did not use a standard syllabus; the CFI taught pitot tube checks but not the drain hole. The CFI instructed to never use 40 degrees of flaps unless necessary. Neither the student nor the CFI owned the pilot operating handbook; they used a standard checklist kept in the airplane.
Aircraft Information
The Cessna 172M has a wingspan of 36 feet 1 inch. The Owner's Manual states that at maximum gross weight, standard conditions, with 40 degrees flaps and no headwind, the ground roll is 520 feet; from 50 feet above ground, total landing distance is about 1,250 feet. These distances reduce 10% per 5 knots headwind; with an 8-knot headwind, reduction is about 16%.
Airport Information
Controllers reported the go-around instruction was issued when the airplane was about one wingspan above runway 21 overflying the intersection at A2/B2, about 1,150 feet from the runway end. About 75 additional feet of paved surface exist before the terrain slopes downward. Wind was 210 degrees at 8 knots.
Air Traffic Control Information
At 1421:27, the pilot requested a shoreline departure with VFR flight following. After takeoff at 1423:38, he reported the airspeed indicator failure. The controller cleared him for landing at 1424:34. At 1426:12, the airplane crossed the approach end, remaining airborne for about 3,800 feet down the runway. The controller believed the airplane was too high and insufficient runway remained; he issued the go-around at 1426:36. The pilot acknowledged. At 1427:08, another aircraft reported the Cessna went off the end. The controller contacted the fire department. Attempts to contact N5155Q were unsuccessful. During the go-around, the airplane impacted trees about 900 feet west of the departure end of runway 21, then the house.
Wreckage and Impact
The airplane first struck a tree about 900 feet west of the departure end at an estimated elevation of 100 feet msl. The departure end elevation was 118 feet msl. The distance between the tree top and main wreckage (partially on a block wall) was about 85 feet.
Tests and Research
Examination of the recovered airplane revealed the pitot tube was blocked by debris between the ram air inlet and the drain hole. No other mechanical anomalies were found. The engine rotated with thumb compression in all cylinders, no anomalies noted. Spark plug leads were crushed and torn; no spark from magnetos. Top spark plugs showed normal combustion signatures. Carburetor, gascolator, and wing tank fuel screens were clear. The propeller showed forward and aft bending and chordwise scratches.
Pitot tube debris was sent to the NTSB Materials Laboratory. Visual examination revealed light brown/tan granular particulates similar to sand or soil. An entomologist found a small amount of insect cuticle but no signs of nesting. Scanning electron microscopy and energy dispersive x-ray spectroscopy showed aluminum, silicon, oxygen, magnesium, and iron, consistent with sand or soil. Internal surfaces had no marks or debris; a small space between the nozzle head and threaded portion contained material similar to the submitted debris.
Additional Information
According to Cessna Pilot Safety and Warning Supplements, if the pitot tube ram air inlet is blocked, the airspeed drops to zero; pilots must rely on pitch attitude and power settings. The POH recommends 40 degrees flaps for short field landings. The FAA Pilot's Handbook of Aeronautical Knowledge states that if the pitot tube becomes blocked and the drain hole remains open, the airspeed indicator reading decreases to zero as dynamic pressure cannot enter.