The laws of physics do not change when the sun goes down, therefore, the aircraft flies the same at night as it does during the day—it is the pilot that behaves differently. And sometimes, this leads to accidents.
Recognizing that the cloak of night influences the outcome of accidents, the Aircraft Owners and Pilots Association (AOPA) Air Safety Institute (ASI) is offering new analysis of night flight accidents. The purpose is to identify the causal factors in accidents that occur at night and to help pilots develop strategies to mitigate these factors. The report looks at accidents that happened during night flying from 2017 to 2021. For the purpose of the report, “night is defined as beginning at dusk and ending right before dawn.”
The FAR/AIM goes into more detail. In Part 1 definitions, night is defined as the time between the end of evening civil twilight and the beginning of morning civil twilight. Morning civil twilight begins when the geometric center of the sun is 6 degrees below the horizon and ends at sunrise. Evening civil twilight begins at sunset and ends when the geometric center of the sun reaches 6 degrees below the horizon.
Most pilots learn the Part 61 definition of night, which refers to one hour after sunset and ending one hour before sunrise. Between those hours no person may act as pilot in command (PIC) of an aircraft carrying passengers unless within the preceding 90 days that person has made at least three takeoffs and three landings to a full stop during that night period.
Part of the challenge with night flight, according to ASI, is that many pilots focus on regaining currency for night flight with three takeoffs and landings, but they do not allow sufficient time to gain proficiency.
Causal Factors of Night Accidents
According to the report, the top four accident causal factors are: loss of control in flight, engine and propeller failure, fuel exhaustion or fuel mismanagement, and loss of control on the ground accidents.
Loss of control often results from a pilot experiencing spatial disorientation and putting the aircraft into an unusual attitude in an attempt to “fix” the issue.
Spatial disorientation is defined as the inability of a person to determine their body position, motion, and altitude relative to the earth of their surroundings. During the day and in visual flight rules, the pilot determines orientation by looking out the windscreen at the horizon.
At night the horizon can be difficult to discern, and often there are visual illusions. For example, the Pilot’s Handbook of Aeronautical Knowledge warns pilots that a line of house lights on rising terrain can be mistaken for stars in the sky. If the pilot mistakes the line of lights for the horizon, it can make them think the airplane is in a steep bank when actually it is straight and level. Experiencing this loss of situational awareness, the pilot attempts to correct the situation, but in reality they have put the aircraft in an unusual attitude resulting in a loss of control.
Moonless nights, marginal VFR, and IFR conditions at night can add to the challenge of maintaining situational awareness. In addition, the lack of illumination to see terrain and known ground landmarks can further erode a pilot’s situational awareness.
“Night flying introduces challenges that are reflected in the data,” said Robert Geske, ASI manager of aviation safety analysis. “More than one-quarter of fatal night flying accidents occurred because of spatial disorientation, a condition that can bring about loss of control in flight—the leading cause of all night flying accidents.”
Accidentally Out After Dark
A study of accident reports compiled by the National Transportation Safety Board notes that often the pilot involved in an accident may have been night current but not night flight proficient.
It is not uncommon for pilots to satisfy the night requirement for a certificate or rating then never or very rarely fly at night again. Instead, they find themselves “caught out” at night when there have been delays during the day.
Personal flights dominated fatal and non-fatal accidents. The ASI suggests the way to mitigate this is for pilots “to routinely seek instruction during night flights with an emphasis on en route, climb, and approach phases to help reduce accidents.”
The report noted the majority of the accidents took place during the en route portion of the flight when a loss of situational awareness resulted in a loss of control resulting in a stall-spin accident.
“Training that emphasizes low-speed awareness and stall recognition and prevention should reduce these deadly accidents,” the report stated.
According to the report, between 2017 and 2021 there were 464 fixed-wing general aviation (GA) accidents with 150 ending in a fatality. Of that, accidents taking place at night accounted for 7 percent of the total. “However, fatal night accidents account for 16 percent of fatal GA accidents,” highlighting the risks associated with night operations, AOPA said.
Accidents taking place in instrument meteorological conditions were the deadliest, as more than 67 percent of those resulted in fatalities, the report said. Darkness can also make it more difficult to determine issues that can lead to an accident. For example, a pilot might not notice smoke in the darkness or that the wrong color of aviation fuel is being added to their aircraft.
Equipment for Night Flight
Proper pilot equipment for night flight and cockpit organization are key. The pilot should have the cockpit set up before engine start. Reaching into the darkness of the backseat for something stowed in a flight bag can prove dicey.
It is important for the pilot to have an appropriate flashlight. While the flashlights app on a smartphone might be useful for the preflight inspection, it will not work in the cockpit, and white light destroys night vision. Instead, the pilot should have a flashlight with a colored lens such as red, green, or amber. These hues allow a pilot to maintain their night vision in the cockpit.
ASI suggests pilots add night proficiency training to their regular flying and, under the watchful eye of a CFI, perform basic maneuvers such as climbs, turns, descents, slow flight, and stalls in addition to takeoffs and landings.
