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).  Using this technique, known obstacles, such as towers,  will be avoided. When automated flight equipment is not available, great  care must be taken to prepare properly for a night flight.  SRM becomes more challenging under the cover of  darkness, and caution should be exercised when determining  what artificial light source to use inside the aircraft. A light  source that is too bright will blind the pilot from seeing  outside obstacles or rising terrain. Certain colored lenses  bleach out symbols and markings on a map. Conduct this  planning on the ground, in a dark room if necessary, before  the actual flight. Pilots must be even more conservative with their decision- making and planning when flying at night. Flying becomes  more difficult due to the degradation of our sensory perception  and the lack of outside references. Beginning with preflight,  looking over the helicopter with a flashlight can cause pilots  to miss even the smallest discrepancy that they would easily  see during the day. For example, failing to remove one or all  of the tie downs and attempting to take off would probably  result in a dynamic rollover accident. Whenever possible,  preflight inspection should always be conducted during the  day or in a lighted hangar. Depth perception is less acute;  therefore, hover height should be increased to avoid contact  with obstacles and hover speed should be reduced. Weather  conditions can be very deceptive and difficult to detect in  flight under night conditions. On a low-illumination night,  it is easy to fly into clouds without realizing it before it is  too late to correct.  Due to the number of recent CFIT night accidents, the NTSB  issued a safety alert in 2008 about avoiding night CFIT  accidents. That alert included the following information: Limited outside visibility is one constant in CFIT accidents.  In the accident cited at the beginning of this section, it  appears the pilot failed to obtain a weather briefing. If the  pilot had obtained one, he would probably have learned  of the cloud cover and light precipitation present along  his planned route of flight. The limited outside visibility  probably caused the CFIT accident, since no evidence was  found of any pre-impact mechanical discrepancies with the  helicopter’s airframe or systems that would have prevented  Of particular note in the 2008 safety alert is a comment  regarding oxygen use above 5,000 feet. Most helicopters  are neither required nor equipped for supplemental oxygen  use at this altitude. Due to the physiological effect on night  vision of reduced available oxygen at higher elevations, care  should be taken to exercise light discipline. Interior lighting  should be lowered to the lowest possible levels but must allow  adequate illumination of necessary systems and instruments.  This, in turn, allows greater recognition of outside obstacles  and terrain features.  •  When receiving radar services, do not depend on ATC  to warn of terrain hazards. Although controllers 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.  •  When ATC issues a heading with an instruction to  “maintain VFR,” be aware that the heading may  not provide adequate terrain clearance. If any doubt  exists about your ability to avoid terrain and obstacles  visually, advise ATC immediately and take action to  reach a safe altitude.  •  For improved night vision, the FAA recommends the  use of supplemental oxygen for flights above 5,000 feet. •  Obtain as much information about areas in which you  will be flying, and the routes to them, by utilizing  hazard maps and satellite imagery.  •  Before flying at night to unfamiliar remote areas or  areas with hazardous terrain, try to arrange a day flight  for familiarization.  •  If a pilot flies at night, especially in remote or unlit  areas, consider whether a global positioning system  (GPS)-based terrain awareness unit would improve  the safety of the flight.  Figure 13-10.  Helicopter heading straight for mountain.  •  Terrain familiarization is critical to safe visual  operations at night. Use sectional charts or other  topographic references to ensure the helicopter will  safely clear terrain and obstructions all along the route.  •  When planning a nighttime VFR flight, follow IFR  practices, such as climbing on a known safe course  13-17