Night Flying – Know the Dangers
There are lots of great reasons to fly at night, and pilots who choose to should embrace it and learn more about it. For starters, the views can be truly spectacular. Metropolitan areas are extremely well lit, and the lights sometimes look like jewels spread over the cityscape. Metro areas are probably among the safest places to fly at night since, even on a moonless night, the bright lights from below make it easier to spot adjacent terrain and obstacles. If you want to avoid turbulence, night is one of the best times to fly. Winds die down at night, which reduces mechanical turbulence, particularly over hills and terrain. Thunderstorms also tend to dissipate at night, which enhances safety in regions prone to storms. There’s also far less competing air traffic at night. Less than 5% of GA flying is done at night, so there’s less competition for the airspace, and ATC will have more time to talk with you. Aircraft are also easier to spot at night, though occasionally it’s harder to perceive how to avoid traffic at your altitude.
Many things are different that make night flight more inconvenient. Some of the differences also make night flight more dangerous. First, we’re not nocturnal creatures, and it’s much harder for us to see at night. Our eyesight is best suited for the daytime, and most everything we do at night just becomes a little harder. This includes pre-flighting the aircraft, finding switches in the cockpit, taxiing, reading maps, spotting terrain and obstructions, and of course, landing the aircraft. GA aircraft often have poor cockpit lighting, which also contributes to the problem. There are many other challenges. Navigating becomes more difficult, since landmarks are harder to identify.
Many airports have fuel available only during business hours and have no services at night. In fact, some airports aren’t even lit and so don’t permit night landings. Fatigue is also a factor. Most people are tired at the end of the day and may not have the same judgment and reaction time they have in the daytime. Spatial disorientation, which can lead to loss of control of the aircraft, is also more likely at night, particularly on dark or hazy nights that lack a clear horizon. Inadvertent flight into a cloud is far more likely at night than in the daytime, since clouds are difficult to spot at night under even the best of circumstances. Many VFR into IMC accidents occur at night, which suggests that you’re more likely to have this type of accident at night. In unpopulated areas with little light, it may be impossible to see and avoid clouds.
Emergencies are also more difficult to manage at night. An alternator failure leading to a loss of electrical power may be a minor inconvenience in the daytime but becomes more serious at night. And if you were to have an engine failure at night, selecting an appropriate off-airport landing site is far more difficult than it would be in the daytime.
Night flight is challenging and people deal with it in different ways. Some choose to avoid night flight altogether. Others educate themselves on the risks and set their own personal minimums for the conditions under which they’re willing to fly at night. Either way, understanding all of the factors that affect night flight will make you a safer pilot.
If you’re going to fly at night, then put the odds on your side. While it may seem obvious that flying when the moon is out will help, it will probably surprise you how much it will reduce your chances of an accident. One book, The Pilots Night Flying Handbook, by Buckwalter, cites US statistics that shows the relationship between night flying accidents and flying in “dark night” conditions. Examples of this would be flying during a new moon or below an overcast that obscures the moon. Here is some of the data cited, where the numbers represent the number of accidents under different lighting conditions:
As you can see, there’s more than a one to 10 difference in the number of accidents when flying in bright night versus dark night conditions. Few things have this big an impact upon the accident rate, so consider this whenever you fly at night.
One of the best ways to reduce night accidents is to get an instrument rating. Paul Craig, author of The Killing Zone, found in his research that for a given number of hours of experience, a pilot with an instrument rating had significantly fewer accidents than a pilot without one. This relationship held regardless of a pilot’s total flight time. So, statistically, a pilot who spends his hours getting additional ratings has far fewer accidents than the pilot who spends the same number of hours flying around getting R1000 breakfasts.
In her article Into the Night, Phyllis Anne Duncan gives a breakdown on night VFR flying accidents, 46 of the accidents had a probable cause concerning pre-flight, 14 occurred during the taxiing or standing phase of flight, 73 occurred during the take-off and climbing phase, and 223 occurred during the approach and landing phase. Clearly, we’re at greatest risk on a night flight during approach and landing phases. But all phases have risks.
Most discussions of pre-flight for night flying properly emphasize the need to see that all of the legally required lights are working and that you have sufficiently bright light for the pre-flight inspection. In addition, make sure that you check the cockpit lighting in the plane before you go. Lighting varies considerably, even among airplanes of the same make and model, and you may be in for a surprise if you don’t check this on the ground. In addition, pay particular attention to your electrical system and make sure that the alternator is operating and charging the battery. While a loss of the electrical system in daytime VFR may be a minor annoyance, it can be a full-blown emergency at night if you’re unable to use your radio to activate pilot controlled lighting at your destination. All pilots learn about the need to adapt their eyes to the dark, and the long period required to do this. However, most people probably don’t brief their passengers about the need for the pilot to preserve that adaptation in the air. One example is a pilot downwind for a night landing, when one of his passengers said, “hey look” and then snapped his picture with a flash camera!
The causes of taxi accidents are fairly obvious: Many airports are poorly lit at night, and if you’re not very careful while taxiing, you may strike an object on the ground. Fortunately, most of these accidents are not fatal.
Take-off and climb out
Take-off over unlit ground or water can be particularly dangerous, even to high time pilots, if there are few visual ground references. There are many accidents on record where the departing pilot crashed on take-off by descending into the ground, usually within the first mile of departing the airport. How could a pilot, much less an experienced one, crash like this? The answer is in the somatogravic illusion, which is discussed in most instrument training classes but is rarely mentioned in night training for private pilots. According to the FAA Instrument Flying Handbook, “… a rapid acceleration, such as experienced during take-off, stimulates the otolith organs in the same way as tilting the head backwards. This action creates the somatogravic illusion of being in a nose-up attitude, especially in situations without good visual references. The disoriented pilot may push the aircraft into a nose-low or dive attitude. A rapid deceleration by quick reduction of the throttle(s) can have the opposite effect, with the disoriented pilot pulling the aircraft into a nose-up or stall attitude.” So, what happens? A pilot taking off at night will experience the acceleration as a climb and release yoke pressure, allowing the airplane to descend into terrain. The same thing occurs often when instrument pilots reach the missed approach point and add full power to do a go-around. They perceive the acceleration as a climb and then, rather than pitch and trim for climb at maximum climb rate, continue to fly level at the worst possible time: close to the ground and possibly in IMC conditions.
In the Cruise
The cruise phase of flight is generally the safest, but illusions like false horizon can deceive a pilot. This is when a sloping cloud formation, an obscured horizon or certain geometric patterns of ground lights can lead to a pilot misperceiving the true horizon and putting the aircraft into a dangerous attitude. In hazy or dark night conditions, flying with reference to instruments is almost a necessity. If you cannot see the horizon, it’s hard to keep the airplane straight and level without using the instruments. The obvious paradox is that a private pilot may go years without any additional training on instruments yet is “legally” allowed to fly in dark night conditions. Remember that legal and safe are two separate concepts, and while you may be legal to fly at night, you will want to get whatever additional training is needed to assure that you are also safe. Choosing a non-direct route at night can also enhance safety if you were to have an emergency and needed to land. Plotting a route over airports or along freeways can enhance your safety if the unthinkable occurs. Also, it’s a lot easier to inadvertently fly into a cloud at night. If you do fly into a cloud, generally a 180 turn (using your instruments for reference) is the safest way to slowly extricate yourself from that position. Maintaining a safe altitude is also critical.
Approach & Landing
Most pilot have heard of “black holes,” where an aircraft crashes short of an airport when approaching to land due to an illusion created when there are few lights on the ground between the aircraft and the airport. Few, however, know of the studies done by Boeing engineers that have proven that, in black-hole conditions, pilots consistently fly below a standard, three-degree glideslope and often crash short of the runway! One strategy for dealing with black-hole approaches is to use the VASI or ILS glideslope to maintain a safe altitude on approach, though not all airports have these. However, with the wide availability of GPS (or DME when there’s a VOR on the field), you can approximate your own three-degree slope. On a three-degree glideslope, you’ll descend 318 feet for each nautical mile you travel. So, while on approach, stay at least this high above the ground for every mile away from the runway. In any case, avoid very long, straight-in approaches at night, particularly if no glideslope guidance is available. You will be much safer flying a regular circuit with a shortened final, rather than flying a long, straight-in approach over many miles.
Planning - 7P’s come to mind (Previous Proper Planning Prevents Piss Poor Performance)
Know the challenges in your local area and how to navigate your way through them, it’s important to have a plan before you leave the ground. In the daytime, fly routes and passes that you commonly fly at night and determine the minimum altitude you are willing to use at night. If an overcast prevents you from maintaining that altitude, plan early to make a 180-degree turn and land at another airport still in the clear. Then you can phone a friend to get you, rent a car, or stay in a B&B. Always consider alternatives, but remember that “hoping” things will work out is not an alternative! Plan ahead and select an alternative with a guaranteed known outcome.
Clearly night flight is different and requires more care and planning, it also requires an understanding of the possible illusions. Develop your own strategies for night flight, stay in your comfort zone and enjoy the view!