by Ray Leis
If you are night current and have been for some time, an unintentional flight termination at night is no big problem. But for those who havent kept up their night-flying skills, there may be a number of unwelcome pop-up hazards.
Flying at night should be just as safe as it is in the daytime, but it isnt.
Approximately 28 percent of fatal accidents and about 14 percent of non-fatal accidents occur at night – despite the fact that less than 5 percent of general aviation flying is done at night. Accidents at night fall into a handful of primary categories: engine failure due to fuel mismanagement, controlled flight into terrain in good weather, taking off or landing with inadequate lighting, bad weather, and alcohol consumption.
Although the risks are real, there are some advantages to flying in the dark. Cooler temps means less of a problem with high density altitude in the summer. There is less traffic to contend with, and whats there is more readily visible.
That said, there are three critical risk factors concerned with flying at night. Just as in day flights, they are the pilots instrument proficiency, the environment in which the flight will occur and the aircraft involved. The only problem is, the requirements carry a bit more weight at night because you cant see whats happening around you as well.
Before You Launch
Starting with the preflight inspection, darkness complicates things. You cant simply look at a sumped fuel sample, for example, because you cant reliably tell the color of the fuel while using a flashlight.
You can shine the light from the side and hold the sample against a white piece of paper and then give it the smell test, but thats a layer of complexity that doesnt exist during a day preflight.
Its harder to tell how much fuel you have because your head blocks the flashlight beam or your flashlight blocks your vision into the tank. A micro flashlight helps here, or else use a dipstick – which isnt such a bad idea to do routinely anyway.
And then there are other hard-to-spot-in-the-dark items, such as frost on the wings, damaged tires, prop nicks, fluid leaks, and more. The solution is to do what the pros do. Make a thorough preflight in the daylight, augmented by a walkaround just before you fly at night.
Inside the airplane, pay particular attention to the electrical system, lighting and instruments. That means you have to have confidence in the alternator, and the battery should hold a good charge. The lights should all work, including the oft-neglected landing light. Pay particular attention to panel lighting.
Select your destination airport carefully. Although general aviation pilots can legally and safely land at airports without lights, its best to use airports that have at least VASI lights. PAPI lights are better. And if the runway is served by an ILS, use it even in visual conditions.
Check how the pilot-controlled lighting works. Some airports use an unusual frequency or a weird number of clicks on the mic to turn the lights up or down. Know how keying the mic will change the lighting because bright approach lights combined with dim runway lights can really present you with a confusing set of visual cues.
Plan the times when you will key the lights on, both for approach and departure. The last thing you want is for the lights to turn themselves off at a critical moment because you keyed them on prematurely.
Since pilotage will be difficult, its best not to rely on it when flying VFR at night. That means you should not only be ready to use any available navaids, but also have a backup on hand, such as a portable GPS receiver. Precautionary landings will be dicey, so keep track of airfields along your route and know which one youll go for at any given time.
If you do rely on pilotage, select checkpoints that can be seen at night. It seems obvious, but many prominent landmarks are difficult to spot at night. Make note of power lines, tall towers, mountains and any kind of obstacles around your destination airport.
Night flight is actually serious IFR flying in many cases. Often you cant see the weather ahead or above you. It is very easy to fly into weather. If you dont go on instruments immediately after losing visual references there is serious trouble ahead.
Youll need to pay more attention to instruments at night than in daylight simply because there are fewer visual cues at night – and the ones that are there get interpreted differently than during the day.
Visual cues can trick you into following false horizons, for example, that are generated by the mixture of ground lights and stars. The result can quickly be unusual attitudes.
VFR pilots depend greatly on being able to judge distance from the ground and in relation to objects around them. You know approximately how high you are or how far you are away from something by the objects size and how clearly you see the details.
Those visual cues grow less distinct at dusk and even more so at night. The picture changes. This is true especially if you are descending from dusk into surface darkness. Youll be moving into what is essentially instrument flight. Be ready for it.
Instrument flight is the best way out of these potentially dangerous positions at night. The same rules apply as they do in IFR flight: Disregard sensations you may have and rely on the guidance of the instruments.
One of the main reasons for general aviations poor night safety record comes down to the fact that human beings just dont see well at night. There are things you can do to compensate for this problem, though.
For starters, combine a solid knowledge of night-flying techniques with good fundamental execution of cross-country procedures. You should also have a better-than-average grasp on emergency procedures and your landing skills should be sharp.
If you cant put all of these elements together, you dont want to think about night cross-country. Nor do you want to push it too close on a flight you plan to conclude during daylight. Mix adverse winds, a change in destination weather or a delay in takeoff with shorter daylight hours and you can easily find yourself arriving in the dark.
While cruising in the dark, its quite clear that seeing the weather you are about to fly in to is far from certain. You wont see rain or clouds until youre almost in them, unless the moon is bright. You wont have a feel for turbulent buildups. Fortunately, thunderstorms make their presence known by lightning that can be see from far away.
If you are concerned about weather in the daytime, double your concerns about IFR flight at night. Youll want to get the best briefing you can – as early as you can and right up to departure time so you can spot trends. Keep in mind that the accuracy of surface observations can decline at night, particularly if they are gathered by a person.
Special Night Circumstances
There are two instances in particular where night operation is quite different from day operations. Both are related. The first is what is known as dark night conditions. When the moon is obscured or new, the sky is so dark that sparsely terrain, open water and sky become indistinguishable. The other is when you take off over a body of water and the sky reflects the water such that you feel youre flying in outer space.
In either case, intense vertigo can come on quickly. Sparse lighting on the ground may look like starlight. Overcast skies may look like forest. This is a confusing and dangerous situation.
Unless you refer to an artificial horizon, a turn and slip indicator or an autopilot, there is absolutely no way to keep the wings level until visual references return. Some pilots claim success using the floating magnetic compass or the ADF needle for leveling reference, but I have never seen a pilot successfully use these methods to stay out of unusual attitudes while under the hood or on a dark night.
Disorientation is a particular problem, due to the role your eyes play in keeping your other senses in line. The middle ear cant accurately report the forces involved in flight and tend to send the wrong signals to the brain. Once you lose the visual horizon, you must depend on senses that are reporting too little or too much, and too late. The result is confusion and a feeling that the airplane is going in a different direction and attitude than the instrument panel indicates.
I have always found it easy to induce night vertigo in student pilots training for the night checkout. Put the airplane in a steady turn and have the student look at the floor of the cockpit. Next, ask the student to make a sudden head movement. Spatial disorientation and vertigo sensations arrive immediately.
If the pilot believes his bodys false signals and tries to fly the airplane by feeling, confusion multiplies into panic. By making the wrong control inputs, the sounds of engine and feel of the controls add to the out-of-control feeling. The chances of recovery from this point on melt away.
There are some tricks to preventing vertigo. Primary among them is to keep your head still while the airplane is turning. Dont look down to a chart, dont switch fuel tanks, dont try to pick something up off the floor until the airplane is out of the turn.
Avoid any long, spiraling turns or circling in a continuous pattern when night visibility is poor. As you try to shift your attention between the view outside and the instruments, you not only have to move your head, you also are faced with interpreting both situations and reconciling them with your physical sensations.
If disorientation does set in, you can stop it simply by reverting to flying by instruments. Scan the gyro instruments and try to ignore the physical sensations – a feat easier said than done the first time you experience it. Lock your eyes on the instrument panel without fixating on one specific instrument and put the airplane in a straight-and-level attitude. If you believe the instruments are right it will go a long way toward defeating the vertigo.
The nighttime demands on your body go far beyond your rods and cones, although accepting the limitations of your eyes is part of the battle. You must also accept the fact that, unless you are a shift worker and well-acclimated to working nights, your circadian rhythms will result in your mental alertness beginning to deteriorate at about 7 p.m. to 8 p.m., reaching a low point at about 5 a.m.
Things start to come apart as fatigue increases. Decision-making and flying skills may appear to you to be normal, but they will be far from it. The affects are in some ways similar to alcohol impairment in that one of the first things to go is your ability to tell if anything has gone.
As for your eyes, remember the rules of thumb for maximizing the use of your rods. The way you look at things can influence how well you can see them. At night, look slightly to the side of the object you want to see rather than focusing on it directly.
You have to focus the image away from the center of the eye – where there are only cones. To replace straining and staring in the dark, shift your gaze frequently and systematically, over the area you are putting in focus.
Night flying can be safe and enjoyable. It can help you make more use of your airplane. Dont take it too lightly, however, because there are some serious challenges to overcome.
-Ray Leis is an ATP, CFII and FAA Aviation Safety Counselor.