The NTSB began 2008 by issuing a Safety Alert aimed at general aviation (GA) pilots. It deals with accidents involving controlled flight into terrain (CFIT) during nighttime VFR flight. The NTSB noted that some of the CFIT accidents it has investigated in recent years could have been avoided if the pilots had maintained better altitude and geographic position awareness. According to NTSB Chairman Mark V. Rosenker, “Some of the pilots involved in these accidents had many years of experience and were instrument rated, yet for some lapses in basic airmanship, they failed to maintain proper altitude.”
In 2003, the FAA determined that CFIT accidents accounted for 17% of all GA fatalities. More than half of the accidents occurred in instrument meteorological conditions. The FAA noted that while small GA aircraft with only a single pilot on board are vulnerable to the same CFIT risks as those facing larger aircraft with multipilot crews, the lone GA pilot must be better prepared to avoid a CFIT accident. In addition to performing all of the flying duties, the lone pilot has to perform all of the preflight planning, route familiarization and en route monitoring. In many cases, an airplane flown by a crew will have more safety equipment, such as a radar altimeter and ground proximity warning system (GPWS), than a single-pilot light GA aircraft.
The NTSB’s Safety Alert contains a number of suggestions to help avoid CFIT accidents, none of which is especially earth shattering. The Safety Board says that CFIT accidents are best avoided through proper preflight planning, and that terrain familiarization is critical to safe visual operations at night. You should use sectional charts or other topographic references to ensure that your altitude will safely clear terrain and obstructions along your route.
According to the NTSB, when you’re planning a nighttime VFR flight, you should follow IFR practices, such as climbing on a known safe course well above surrounding terrain. Choose a cruising altitude that provides terrain separation similar to IFR flights (2,000 feet AGL in mountainous areas and 1,000 feet AGL in other areas).
When receiving radar services, the Safety Board says you shouldn’t depend on controllers to warn you of terrain hazards. Although controllers will try to warn pilots if they notice a hazardous situation, they may not always recognize that a particular VFR aircraft is dangerously close to terrain.
Remember that if a controller issues a heading for you to fly along and “maintain VFR,” the heading may not provide adequate terrain clearance. “If you have any doubt about your ability to visually avoid terrain and obstacles, advise ATC immediately and take action to reach a safe altitude if necessary,” reads the Safety Alert. “ATC radar software can provide limited prediction and warning of terrain hazards, but the warning system is configured to protect IFR flights and is normally suppressed for VFR aircraft. Controllers can activate the warning system for VFR flights upon pilot request, but it may produce numerous false alarms for aircraft operating below the minimum instrument altitude—especially in en route center airspace.
In what has to be one of the great aviation safety understatements, the NTSB suggests that if you fly at night, especially in remote or unlit areas, you should consider whether a GPS-based terrain awareness unit would improve your flight’s safety.
One of the accidents cited in the NTSB’s Safety Alert involved a Piper Saratoga PA32R-301T, which was flown into a mountain peak. The accident occurred at around 10:01 p.m., on November 10, 2004, about 17 nm north of Santa Barbara, Calif. The flight originated at 9:37 p.m., from Bakersfield, Calif. The pilot and both passengers were killed. The pilot had logged 322 hours, including 19 in type, and wasn’t instrument rated. He was a doctor who was expanding his practice to Bakersfield, and had flown between Santa Barbara and Bakersfield a number of times.
A Los Angeles sectional chart was found in the wreckage. It was marked with a line drawn along the direct route between Bakersfield and Santa Barbara, with an “X” depicted at about the location where the accident occurred. Apparently, the “X” was calling attention to the 6,840-foot-tall mountain peak. The fire-damaged remains of a GPS receiver were found in the wreckage.
After takeoff, the pilot contacted a controller at Bakersfield Departure Control and said, “I seem to be in a little bit of, uh, clouds here.” He asked what the ceilings were, and the controller advised, “I don’t have any tops, are you IMC?” The pilot denied being in IMC and the controller advised that the minimum IFR altitude about five miles ahead of the pilot was 3,000 feet, and 12 miles ahead it went up to 6,500 feet, and further along it became 10,000 feet. The pilot advised that he was going to climb to 8,500 feet and that it was smooth and clear.
About 12 minutes after takeoff, the flight was handed off to Los Angeles Center. The flight subsequently climbed to 8,400 feet MSL and then descended to 6,400 feet. At about 10 p.m., the airplane was flying between 6,300 and 6,500 feet when it disappeared from radar. The controller attempted to radio the pilot several times, without success.
Satellite images showed that a band of clouds north of Santa Barbara, extending from west to east, was obscuring higher terrain, including the accident site. Satellite data indicated that the cloud tops were near 10,000 feet. Pilot reports indicated a broken to overcast cloud layer, with tops from 9,000 feet to 11,000 feet, in the vicinity of the accident site.
The NTSB determined that the probable cause of this accident was the pilot’s failure to select and maintain an adequate terrain-avoidance cruise altitude. Contributing factors were the dark nighttime conditions, the rising mountainous terrain and the FAA controller’s failure to issue a terrain-related safety alert.
On February 6, 2007, a Beech King Air medical aircraft was being repositioned from Great Falls, Mont., to Belgrade, Mont. The airplane was on an IFR flight plan and carried an ATP-rated pilot, flight paramedic and a flight nurse. Weather observed at 8:56 p.m., at the Gallatin Field Airport in Belgrade, included an overcast ceiling at 11,000 feet AGL, visibility for 10 miles, wind at 260 degrees at four knots, a temperature of 4 degrees C and a 1 degree C dew point.
The aircraft was being handled by Salt Lake Center and, about 16 minutes after takeoff, the pilot advised that he had the airport at Belgrade in sight. At 8:57 p.m., the pilot was cleared to descend at his discretion from 15,000 feet to 13,000 feet. The pilot acknowledged and stated, “I’ve got the airport in sight at BZN requesting a visual approach.” The pilot was cleared for the visual approach, radar services were terminated and the pilot was told to contact the tower controller at Gallatin Field. At 9:01, the pilot radioed the tower, but most of the transmission was unintelligible. A follow-up transmission also was unintelligible. Investigators learned that it was common for radio transmissions from the area in which the aircraft was located to be garbled and unreadable.
Radar data indicated that the airplane began its descent at 8:57 p.m. from 15,000 feet. At the time, it was about 30 nm north of the accident site. The last radar target associated with the King Air was received just after 9:01, about 13 nm north of the accident site. It was at 11,300 feet MSL. The minimum obstruction clearance altitude (MOCA) for the accident area is 9,100 feet.
The wreckage was located on the north side of a ridge—the highest obstruction between the accident site and the airport. The elevation was 5,700 feet MSL. The airplane struck trees, then the terrain. All three occupants were killed. Investigators found no evidence of any preimpact problems with the aircraft’s engines, propellers or systems.
The airplane was equipped with an enhanced GPWS, but impact damage prevented testing of the unit. Investigators couldn’t determine how the unit was configured during the flight or whether it issued any warnings to the pilot before the impact with terrain. The NTSB noted that the airport is in a large valley and is surrounded by rising mountainous terrain. At night, clouds and the ground are difficult for pilots to detect, and a gradual loss of visual cues can occur as a flight continues toward darker terrain. Additionally, the horizon is less visible and distinct. According to the Safety Board, because the airplane was descending over terrain that provided few visual references, and because the overcast cloud layer would have prevented moonlight from illuminating the terrain, it’s likely that the pilot didn’t see the rising terrain as the airplane continued toward it.
The NTSB determined that the probable cause of this accident was the pilot’s failure to maintain an adequate altitude and descent rate during a night visual approach. Dark night conditions and mountainous terrain were factors in the accident.
Peter Katz is editor and publisher of NTSB Reporter, an independent monthly update on aircraft accident investigations and other news concerning the National Transportation Safety Board. To subscribe, write to: NTSB Reporter, Subscription Dept., P.O. Box 831, White Plains, NY 10602-0831.