Learning Experiences

Low Ceilings And Visibility Spell Marginal Safety

From the start, flight instructors teach their students the importance of understanding and respecting limitations. Perhaps most important is a respect for weather not conducive to safe flight. Regardless of a pilot's experience, certificates, and ratings, or the aircraft, some weather should strictly be avoided. Especially for a pilot without an instrument rating, marginal VFR weather represents a formidable challenge, and a major threat to safety.

Marginal VFR weather is defined as a ceiling between 1,000 and 3,000 feet or visibility in the three- to five-mile range. Many non-instrument rated pilots negotiate such conditions successfully, but their workload and stress level increase - and their margin of safety is reduced. Marginal VFR weather makes navigation and communication more difficult, and pilots often must struggle to avoid clouds, obstacles, and other aircraft. Turbulence and other weather phenomena up the ante, further taxing the pilot's abilities.

One way to deal safely with unfavorable weather conditions is a 180-degree turn. As the pilot in the following report learned, turning around to avoid deteriorating weather isn't always as simple as our training would lead us to believe. This incident underscores how important it is to get a thorough weather briefing and exercise conservative judgment when you make your go/no-go decision.

A student pilot flying a Cessna 152 encountered reduced visibility and snow showers while attempting a solo cross-country flight and attempted a 180-degree turn to divert to a nearby airport. After losing altitude in the turn and fighting turbulence, she decided to make a precautionary landing on a rural road in Erskine, Minnesota. She lost directional control during the landing rollout, and the aircraft struck a snow bank and nosed over. The student escaped injury, but the aircraft was damaged.

The pilot undoubtedly found her workload exceedingly high, and considering her experience, probably exercised good judgment by making a precautionary landing even though it resulted in damage. In the following accident report, the increased difficulty of navigation in marginal VFR certainly contributed to the pilot's troubles.

A VFR pilot flying a Piper PA-32-260 (Cherokee Six) departed from Tulsa, Oklahoma with three passengers on a business-related flight to Bristol, Tennessee. Approaching Bristol, the pilot contacted Tri-City Approach Control and requested radar vectors to the Tri-City Airport. Because the pilot was flying beneath a low ceiling, Approach Control couldn't make radar contact with the airplane.

Flying in turbulence, snow showers, and reduced visibility, the pilot believed he was southwest of the airport, but the Atlanta Air Route Traffic Control Center (ARTCC, or Center) noted that the aircraft was 40 miles northwest of Tri-City. Atlanta advised the pilot of his position, but he proceeded on an easterly heading. The pilot finally decided to land on a street in Dungannon, Virginia. The aircraft touched down hard, bounced, and crashed into the porch of a house. All on board survived.

Studies have shown that pilots are more likely to survive if they execute a precautionary landing and maintain control of the aircraft. If a pilot inadvertently continues VFR into instrument meteorological conditions (IMC), the probability of experiencing vertigo and spatial disorientation is great. The typical outcome is a loss of control and a fatal crash.

Fortunately, the pilot in the previous report elected to make a precautionary landing rather than continue in conditions that might have led to a fatal spatial disorientation accident. In the following case, the pilot attempted to fly VFR in marginal conditions, possibly experienced spatial disorientation, and lost control of the aircraft when he lost his outside visual references.

For a flight in a Cessna 182, the non-instrument-rated private pilot received a weather briefing for a cross-country flight with a passenger. The briefing included reports of mountain obscuration, moderate turbulence, and broken ceilings of 1,500 to 2,000 feet with various cloud layers. Coastal conditions included visibility of three-to-five miles in fog and haze, with some scattered rain showers. The briefer stressed that VFR flight was not recommended, and flight service repeated this admonition when the pilot activated his VFR flight plan.

The aircraft was later reported overdue, and searchers located it the next day by tracking an ELT signal near Fillmore, California. They found the wreckage 3,500 feet up on the east face of a 4,000 foot mountain. Neither occupant survived.

When marginal weather prevails in an area, some pilots are tempted to fly above it. The weather is better above the clouds than below, but the problem is making a VFR descent at the destination. A preflight forecast may indicate that the destination's weather will be VFR, but if the forecast is inaccurate, the pilot may be forced to divert - or attempt a dangerous descent through the clouds to marginal VFR conditions below. The following report illustrates the danger of VFR-over-the-top in such conditions.

Before takeoff, the non-instrument-rated pilot of a Piper PA-32RT-300 (Saratoga) obtained a weather briefing for a no-flight-plan VFR flight. After takeoff, the pilot received an in-flight weather briefing from flight service, which told him VFR flight was not recommended. The pilot then radioed the ARTCC and informed the controller he was climbing to 7,000 feet (that's an IFR altitude) to stay on top of the weather.

Approaching his destination, the pilot called approach control and said he was on top of an overcast and looking for a place to get down. The actual weather in the area at the time is not known for certain, but heavy rain, reduced visibility, low ceilings, and moderate turbulence were forecast. Controllers lost radar contact with the aircraft near Mansfield, Arkansas. Investigators determined that the aircraft flew into trees in a near level attitude, then pitched approximately 60 degrees nose down, and slammed into the ground. Neither occupant survived.

Marginal VFR weather often seems innocuous, and pilots are tempted to continue VFR flight in such conditions in spite of warnings to the contrary. Almost every pilot considers such weather as icing, thunderstorms, hail, and severe turbulence to be serious hazards, but the low ceilings and visibility that define marginal VFR can be just as deadly.

Spatial Disorientation Facts

All pilots are susceptible to spatial disorientation and should take a ride in a Barany Chair (spatial spinner chair) to appreciate its physical effects. Contact the Aviation Safety Program manager at your local FAA Flight Standards District Office (FSDO) for more information.

• Spatial disorientation is the number one cause of fatal accidents.
• Spatial disorientation occurs when a pilot loses the visual cues needed to maintain aircraft attitude, and relies instead on the false cues and sensations from the vestibular system to determine the aircraft's attitude and motion.
• The physical impairments of spatial disorientation may not allow the pilot to read and interpret the aircraft instruments properly.
• The physical impairment may be so severe the pilot can't control the aircraft.
• Instrument-rated pilots are just as susceptible to vertigo and spatial disorientation as non-instrument-rated pilots.
• Spatial disorientation is most likely to occur in low visibility and instrument meteorological conditions. The consequences may be fatal, even if the pilot has an instrument rating.