Friday, January 25, 2008

NTSB: Preventing aircraft accidents involving controlled flight into terrain

NTSB logoThe U.S. National Transportation Safety Board (NTSB) has issued a new Safety Alert that addresses accidents involving controlled flight into terrain (CFIT) during visual night conditions. The Safety Alert arose from information collected during the NTSB's investigations of six general aviation accidents over a three-year period in which "aircraft collided with terrain while either climbing shortly after takeoff or descending to prepare to land."

A press release announcing the Safety Alert says that the pilots and air traffic controllers involved in the six accidents "all appeared to have been unaware that the aircraft were in danger by approaching terrain." The NTSB concluded that all six of these accidents could have been prevented by increased altitude and position awareness, and better preflight planning.

NTSB Safety Alert SA-013 suggests these ways for pilots to CFIT accidents during visual night conditions:
  • CFIT accidents are best avoided through proper preflight planning.
  • Terrain familiarization is critical to safe visual operations at night. Use sectional charts or other topographic references to ensure that your altitude will safely clear terrain and obstructions all along your route.
  • In remote areas, especially in overcast or moonless conditions, be aware that darkness may render visual avoidance of high terrain nearly impossible and that the absence of ground lights may result in loss of horizon reference.
  • When planning a nighttime VFR flight, follow IFR practices such as climbing on a known safe course until well above surrounding terrain. Choose a cruising altitude that provides terrain separation similar to IFR flights (2,000 feet above ground level in mountainous areas and 1,000 feet above the ground in other areas.)
  • When receiving radar services, do not depend on air traffic controllers to warn you of terrain hazards. Although controllers will try to warn pilots if they notice a hazardous situation, they may not always be able to recognize that a particular VFR aircraft is dangerously close to terrain.
  • When issued a heading along with an instruction to “maintain VFR,” be aware that 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.
  • 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.
  • For improved night vision, the FAA recommends the use of supplemental oxygen for flights above 5,000 feet.
  • If you fly at night, especially in remote or unlit areas, consider whether a global positioning system-based terrain awareness unit would improve your safety of flight.
The NTSB alert includes links to the Air Accident Briefs for the six accident investigations that led to the current Safety Alert. Commenting on the results of those investigations, NTSB Chairman Mark V. Rosenker said, "Some of the pilots involved in these accidents had many hours of experience and were instrument rated, yet for some lapses in basic airmanship they failed to maintain proper altitude."