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Forum Home > General Discussion > CESSNA 172 SKYHAWK. SAFETY HIGHLIGHTS

Aviagroup Eduard
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Introduction


   The world’s most popular airplane, not surprisingly, has a great safety record. In this booklet, Cessna 172 Skyhawk Safety Highlights, the AOPA Air Safety Foundation compares 2,405 Skyhawk accidents to 2,364 comparable single-engine, fixed-gear aircraft accidents during the years 1982-1993. With 24,000 Skyhawks in the fleet, that’s a good record, but it is sobering to think that every year about 200 Skyhawks are involved in reportable accidents-

that’s about four per week. Happily, most of the accidents result in little or no injury to the occupants.

   The Cessna was compared to other light four-place aircraft that make up the bulk of the training and entry-level transportation fleet. Included in the comparative group are the Beech Musketeer series, the fixed-gear Cessna Cardinal, the Gulfstream American AA5 Traveler, the Piper Cherokee, and the Aerospatiale TB-10 Tobago.

   In terms of overall accidents per 100 aircraft in the fleet and per 100,000 hours of flight, the 172 had a very slight edge over the comparative aircraft. The FAA estimates annual flying hours from the annual GA Activity and Avionics Survey that includes reports from 30,000 aircraft owners of flying time, landings, fuel consumption, lifetime airframe hours,

avionics, and engine hours.

   The Skyhawk has fewer serious accidents than the comparison group of aircraft—possibly because of its extensive use as a training airplane. Flight lessons for both primary and instrument students are typically given in good weather, so the average student’s exposure to marginal visual conditions or instrument meteorological conditions (IMC) is minimal. As a result, instructional flights have relatively few weather-related accidents. Unfortunately, because of this lack of exposure to poor weather, both newly certificated pilots and new instrument-rated pilots may be unprepared for flight in deteriorating weather conditions.


Serious Accidents


   When studying the pilots of accident flights, one sees some interesting facts emerge. Forty percent of all serious accidents occur in the first 200 hours of total time. Just after pilots obtain their private certificates, the accident involvement goes up significantly. This is not unique to the 172 and indicates that as new pilots begin to enjoy the freedom of their certificates, they also encounter some situations that exceed their experience level. Overconfidence is subtle and dangerous. Get as much training in diverse situations as possible and explore the new world of flight cautiously. A private pilot certificate is not the end of learning, but rather the beginning.

   A 72-hour VFR (visual flight rules) Skyhawk pilot was advised during the weather briefing that VFR flight was not recommended due to low ceilings and visibility just east of Panama City and along the Gulf Coast. Approximately 28 miles southeast of the destination, the pilot contacted Eglin Approach Control and was advised that the weather was IFR. There were no further communications with the pilot. The aircraft then appeared to be in an orbit, and a few minutes later, radar contact was lost. The pilot and two passengers were killed. The 55-year-old pilot had received his pilot certificate two weeks earlier.


   Half the pilots involved in serious accidents in both the Cessna and comparison aircraft had fewer than 100 hours in type. The unfortunate pilot in the accident above attempted a flight well beyond his skill level. It is likely he had little or no exposure to flying in marginal VFR, and he probably had not flown in actual IFR with his instructor. The combination of no actual weather experience and very poor judgment in his disregard of VFR weather minimums culminated in the loss of three lives. Pilots should either restrict their solo cross-country activities until they have more time in various weather conditions, or the checkouts

need to be more rigorous. A combination of the two is the most desirable solution. Several flying clubs insist that new pilots have at least five hours solo before taking

passengers, if the pilot has less than 100 hours total time.

   This may seem to negate the reason for checking out in the aircraft in the first place, but it provides for fewer distractions and allows the new pilot to sharpen the basic aircraft handling skills that the accident records show are needed. These flying clubs will also pay close attention to weather before dispatching the new pilot.


Weather


   Most weather-related accidents are preventable. Weather forecasting and weather information dissemination has improved immeasurably over the past few years. It is not a

guarantee, however, that once in flight, the actual weather will match the forecast. Obtain a weather briefing and monitor weather reports en route. Do not continue into bad weather. Every flight should include an alternate course of action in case the forecast is worse than expected.

   This advice is life saving. It is easy to say but much harder to put into action due to the desire to complete the trip.


Night


   Flying at night increases the risk of an accident. The reason is simple—it’s harder to see where you’re going. Other factors compound the challenge. If you are over 40 years of age, your vision probably isn’t as sharp at night as it used to be. Visual acuity also diminishes with fatigue and altitude. Many Skyhawk cockpits are poorly lit with dim overhead lights and little or no flight station lighting for map reading. While dim lighting preserves some of the

eyes’ ability to adapt to the darkness outside, it is not bright enough to read charts clearly, so you often have to juggle a flashlight into the work load. Add IMC to this scenario, and the risk of an accident increases.


"Since any degree of dark adaptation is lost within a few seconds of viewing a bright light, pilots should close one eye when using a light to preserve some degree of night vision. "


   Cessna Pilot Safety and Warning Supplements, 1985 Pilots who fly cross-country at night should be well versed in airport lighting and publications such as the Aeronautical Information Manual (AIM), which not only describe the lighting available, but tell how to activate runway lighting at nontowered airports. If you are unfamiliar with the destination airport, take time to acquaint yourself with the airport approach lighting and surrounding

obstructions.

   Accident data suggest that instrument training and currency would greatly improve the safety of night VFR operations. The number of noninstrument-rated pilots involved in night accidents is more than three times that of instrument-rated pilots. This indicates that spatial disorientation may be a factor in night accidents. The use of published instrument departures and approaches at night ensures terrain and obstruction clearance. Use the VASI

and ILS glideslope. Avoid short runways and small unfamiliar airports after dark.

   When descending toward a distant city, keep a sharp eye on the lights at the edge of the city closest to the aircraft. Should any of these lights disappear, then something such as a ridge has risen to block the view. Start climbing immediately until the lights are once again visible.   

   As long as these lights remain in sight, the aircraft is above all en route terrain.


The owner, a CFI, was in the right front seat and a private pilot with no instrument rating was in the left front seat of the Skyhawk. The night flight was from Florida to Esler Regional Airport in Louisiana. There was no flight plan filed. During arrival, they had inquired about the weather at Esler Regional Airport; however, the FSS and unicom had closed earlier that night, and current weather observations were not available. At that time, the England AFB

weather was clear, visibility 3 miles with fog. At about 0300, they elected to make an approach to "see what it looks like." During the ILS approach, the aircraft collided with trees about 40 feet above ground level. Both pilots were killed. Weather at the time of the accident was 600 feet overcast, partial obscuration with fog. The CFI had been awake since 0400 of the previous day and had continued the trip to get back to work.


   Flying in IMC when fatigued impairs even the best pilot’s judgment. Add to that night, and the pressure of "having to get there," and you have a flight plan for disaster.


Instrument meteorological conditions (IMC)


   The 172 is involved in IMC accidents about two-thirds as often as the other light singles.

These accidents include noninstrument-rated pilots who continued flight into instrument meteorological conditions, as well as instrument-rated pilots on IFR flight plans.

   At 0555 EDT, this VFR, 130-hour Skyhawk pilot obtained a weather briefing for a flight from Limington, Maine, to Pawling, New York. At that time, he stated he was unsure when he would depart; it depended on the weather. The briefer advised that VFR flight was not recommended and that the pilot should obtain another briefing before departing. At 0900, the flight departed with an en route fuel stop at Concord, New Hampshire. The route of flight

was to the southwest along Victor 93. When the aircraft was determined to be overdue, a search was initiated.

   Later, it was found where it had crashed near the top of Mount Monadnock at an elevation of 2,900 feet. A witness in the vicinity saw an aircraft matching its description flying below a broken layer at about 2,000 feet msl. He stated that he could see an overcast above the broken layer and that Mount Monadnock was obscured by clouds most of the day.


   Of the 155 accidents occurring in IMC, 64 percent involved noninstrument-rated pilots. The Skyhawk is the first cross-country airplane for many pilots. The high rate of VFR-into-IMC accidents indicates relatively inexperienced pilots are launching cross-country without an

understanding of the weather and a plan to escape if it exceeds their capability.

   Obtaining an instrument rating greatly increases the pilot's chances for a successful flight when IMC conditions are encountered. It is the best single investment a pilot can make to improve trip completion—more so than any piece of equipment you could add to the instrument panel. Once rated, the pilot has the responsibility to maintain currency and proficiency and to obtain an IFR clearance before entering IMC conditions. It is recommended that partial-panel training be included in the pilot's currency requirements.


Structural Ice


Skyhawk pilots need to avoid ice. The Skyhawk is not approved for flight in icing conditions, and most of these aircraft have only a heated pitot tube. Although ice forecasts are notoriously broad and, in some cases, inaccurate, the pilot needs to have an escape route if ice is encountered. The AOPA Air Safety Foundation’s Safety Advisor, Aircraft Icing, discusses both structural and carburetor icing, and how to fly safely when icing conditions are forecast.


Carburetor Ice


   Accident summaries contain many reports of unexplained power loss. At least some of these may be attributed to carburetor ice. At the first indication of carburetor ice (unexplained engine roughness or power loss), apply full carburetor heat and leave it on. Partial heat should not be used. The engine may run rougher as the ice melts and goes through the engine, but it will smooth out again.

   A 106-hour Skyhawk pilot reported that the engine began to run rough and lost power as the airplane climbed through 9,000 feet msl. She then switched fuel tanks and moved the mixture to full rich, but the engine continued to lose power. Carburetor heat was not used at any time.

   A forced landing was subsequently made in a field, where the airplane collided with a utility pole and landed in a ditch. An examination of the engine revealed no evidence of preexisting mechanical failure or malfunction. An icing probability chart revealed that the reported weather conditions in the area were favorable for the formation of moderate carburetor icing at cruise power. The Cessna 172M owner’s manual notes that a gradual loss in rpm and eventual engine roughness may result from the formation of carburetor ice and prescribes the use of carburetor heat to clear the ice.


Low-Level Maneuvering Flight


   Cessna 172 pilots have more low-level maneuvering accidents than pilots of similar aircraft. The graph shows that 17 percent of all serious Skyhawk accidents occurred while maneuvering compared to 11 percent in the comparative group. Again, this has little to do with the airplane and more to do with the average low experience level of 172 pilots.

   All airplanes handle differently with a full load than they do with a partial load. Most primary flight training is done with just the student and instructor on board- rarely is it done with the aircraft fully loaded. Many Skyhawk pilots experience these different handling characteristics for the first time when loading their airplanes with passengers, baggage, and fuel soon after their check rides. As the weight changes, so does the center of gravity (CG). This affects the

stall characteristics of the airplane, as well as the amount of runway needed for takeoff and landing. A full-load checkout is highly recommended. Many mishaps involve low-level flight interrupted by terrain, obstacles, or water. While flying close to the ground may give a great sensation of speed, the sudden stop that frequently ensues is usually lethal.

   A 700-hour pilot and his passenger were flying low over a sailboat regatta to photograph the boats. The weather was estimated at 700 feet overcast, 3 miles visibility with

light rainshowers and fog. As the pilot maneuvered for a photograph, he throttled back and banked the aircraft in a steep bank. Subsequently, the aircraft stalled, and there was insufficient altitude to recover. The aircraft impacted the water in a left-wing low, nose-down attitude pilot, so they slipped the aircraft for the majority of the final approach. The Mooney pilots did not note the announced position of the Cessna in the traffic pattern or a warning

from another pilot that there were two aircraft landing.

   Fortunately, all four people aboard the two aircraft received only minor injuries. It would have been much safer to enter upwind or downwind and complete the traffic pattern.

In addition to being a primary training airplane, the

   Skyhawk is used extensively for instrument training- usually in VFR conditions. On a nice weekend at busy nontowered airports, VFR traffic will mix with instrument students flying simulated IFR approaches. This combination of straight-in approaches with standard traffic

pattern procedures requires extra vigilance to maintain a safe distance from other aircraft. Instructors must divide their attention between the student and the outside environment, and students should keep their ears open to potential traffic conflicts announced on the radio.

   Instructors should show their VFR students the instrument approach books and explain where the fixes are in relation to the airport. This will help primary students and newly certificated pilots visualize the location of an airplane at one of these fixes.

   Some flight training occurs in marginal VFR conditions. Primary students, both dual and solo, may take advantage of the typically lighter traffic, when the weather is marginal,

to practice in the pattern. These pilots must be particularly alert to approaching IFR traffic when on base and final—or on climbout and crosswind if the winds are such that approaching instrument pilots will circle to land. High-performance singles and business jets fly relatively fast final approaches, and in marginal conditions, there is not much time to react to a sudden appearance of aluminum. VFR and IFR pilots can help avoid the surprise by listening to both the CTAF and approach control.


Takeoff


   It requires more distance to take off than to land. But how much more? The pilot’s operating handbook (POH) states that the takeoff distance required for a Skyhawk at 2,300 pounds, zero wind, sea level, and 59 degrees Fahrenheit is 865 feet, but it can land and roll out in only 520 feet. So it takes about 40 percent more distance to take off than to land. Unwary pilots have skillfully landed their airplanes in tight quarters, only to find they didn’t have enough

room to take off again.

   The numbers in the POH are accurate only under perfectb circumstances. They are based on a new aircraft, excellent test pilot, and flawless performance. Takeoff over a 50-foot obstacle is measured with an optical measuring device, not a 50-foot brick wall.


Density Altitude


   High elevation airports, high temperatures, high gross weight, and high humidity all degrade aircraft performance. The takeoff distance doubles when the same airplane mentioned above takes off from an airport with an elevation of 7,500 feet when the temperature is 57 degrees Fahrenheit. Although most new pilots have learned about density altitude, the airplane’s compromised performance is often unanticipated.

   The 172 has four seats; but unless the fuel load is light, the odds are that the aircraft will be overloaded when the seats are filled—unless you are carrying small children.

   Climb performance is anemic at sea level under this load condition, let alone at high density altitudes.

   An 800-hour pilot with nearly 700 hours in the Skyhawk took off with three passengers on a warm, clear May afternoon in Escalante, Utah. The 5,000-foot runway is 5,740 feet msl, and the temperature was 70 degrees Fahrenheit.

   According to the NTSB report, the density altitude was about 7,500 feet. The aircraft wing tanks were full. The pilot stated that the aircraft would not climb over 50 feet. The stall warning sounded, so he put the wheel forward and the airplane touched the end of the runway, skipped over a gully, and hit the side of a hill. Fortunately, no one was injured. Density altitude was certainly a factor in this accident. The airplane was likely over gross, as well.


For safe mountain operations, double the required runway distance for takeoffs and landings. If the temperature is hot, allow even more distance.


Wind


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September 10, 2009 at 3:36 PM Flag Quote & Reply

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