Presuming that night flying is more dangerous than day flying on the basis of statistics is a fallacy. The airplane does not discriminate between light and dark.

Conditions of night flight are different from daytime flying and it is the pilot's knowledge, or lack of it, combined with a lack of visual clues that present an extra challenge.

A pilot may be subjected to times when the destination airplane lies beyond the rays of the setting sun. Perhaps an engagement becomes a compelling reason to venture out into the black of night.

Flying at night in the mountains is a matter of determining the weather condition to arrive at a personal go/no-go decision.

For those who decide to fly at night, an understanding of night vision differences and adjusting the flight operation accordingly, will increase the margin of safety.

night vision

Even a competent attitude-instrument pilot will need to use his outside vision during a night flight, if only in the transition during takeoff and landing.

What you see, or don't see, in the dark is dependent on the state of dark adaptation of your eyes.

If you enter a dark area, your vision improves slowly. After six to seven minutes the eyes are 100 times more sensitive than when you entered the dark. Full adaptation takes 30 minutes, at which time the rods of the eye are 100,000 time more sensitive.

This is due to the build-up of a photosensitive chemical called visual purple, the key to night vision. Visual purple is dependent on vitamin A (carrots, eggs, milk, cheese and most vegetables). Vitamin A cannot be stored by the body; it is necessary to eat well-balanced meals before night flying.

Although it takes 30 minutes for dark adaptation to occur, it can be lost in a second or two of exposure to bright light. Minimize the use of white light in the cockpit and keep it as dim as possible.

Dark adaptation is an independent process in each eye. If you are exposed t light, close one eye to preserve half your dark adaptation.

scanning techniques

The cones of the eye, used for day vision, provide peripheral vision. Night vision uses rods. This creates a blind spot in the centre of the eye at night. If you detect something with peripheral vision, the natural tendency is to turn and look directly at it. Night vision is impossible at the centre of the eye, so a technique called "off-centre scanning" must be developed. Look six to 12 degrees away from the object you wish to see.

autokenesis

A visual illusion may occur at night if you stare at one light for a long period of time. Involuntary muscle twitches cause the light to be displayed on a different portion of the eye, creating false motion, where the light appears to move. Avoid autokinesis by the off-centre scanning technique.

night take-off and departure

Before departing from a mountain airport at night, firmly fix in your mind the nature of the terrain and obstructions adjacent to the airport.

Pilots have no intention of making an emergency landing shortly after takeoff, especially at night, but it does not hurt to survey the terrain during daylight conditions to form a plan of action.

With the interior lights adjusted to the minimum brightness that affords instrument readability, initiate a normal takeoff.

Acceleration error in the attitude indicator will cause an indication of a higher nose attitude than during a regular climb. As a consequence, some pilots have lowered the nose to the normal attitude and have flown into the ground.

The moment the airplane leaves the ground on a dark night, it is enveloped in black. Outside visual reference becomes impossible. Maintain a positive rate of climb based on the airspeed indication, regardless of the attitude indicator display.

climb out

If you become disoriented during the climb out, terrain clearance becomes a big concern. Fly toward the rotating beacon. At airstrips without lighting, fly toward any light on the ground.

terrain clearance

Proper pre-flight planning includes studying charts and developing a plan of action. Still, at some time during a night flight, you are going to experience a moment of fear arising from your concern about terrain clearance.

If there are any light around, use them. Fly directly toward the light. As you approach this light, select another light. If the light flickers or disappears, there is something between you and the light. Immediately choose another light to fly toward.

If there is only one usable light in the area, a shuttle climb in a holding pattern may be the most prudent course of action.

To perform a shuttle climb, make a 90-degree turn (direction depends on obstructions) and immediately turn the opposite direction for 270 degrees. This is the same as a 180-degree turn, but keeps the airplane confined to a small geographical area.

Before passing beyond the ground light, perform a 180-degree turn back to the ground light. Continue this manoeuvring while climbing to a safe en route altitude before proceeding on course.

weather

It is difficult to see and avoid weather at night. The first indication of a cloud may be a glow emanating from the navigation lights, or a brilliant flash of the strobes being diffused throughout a cloud.

VFR pilots should do an immediate 180-degree turn.

Restricted visibility conditions become apparent with the gradual disappearance of lights on the ground or when they become fuzzy and flow.

Remember, the horizontal visibility through a restriction such as fog, haze or smoke is must less than when looking down through it from above.

Pilots get into trouble trying to land at an airport with fog because they fly over and can see the runway, but when on final approach they can't see anything.

approach for landing

Distances at night are deceptive, due to lack of illumination and inability of the pilot to judge them by the usual method of comparing the size of different objects.

At night, fly towards an airport light and make a standard pattern, rather than attempting a straight-in approach. The perception of distance can be dealt with by flying the downwind leg until the touchdown point is half-way between the wing tip and tail. They turn onto the base leg.

The only way to approach a runway in the mountains at night, with complete safety, is to incorporate the "spot method for landing" technique.

The flare and landing is accomplished in the same manner as during the day. There may be a tendency to look too far down the runway, causing the flare to be too high.

night flying tips

Always carry a workable flashlight (You can recognize the pilot who has flown at night without a flashlight. He's the one that has two or more flashlights in his bag).

Close one eye when exposed to bright light.

Force the eyes to view off-centre.

Blink the eyes if they become blurred.

Do not attempt violent or abrupt manoeuvres at night.

Watch for the disappearance of ground lights or an area of glow around the navigation lights. This indicates entering instrument conditions.

Remember the deceptiveness of altitude and speed at night. A normal approach looks steeper at night, creating an illusion of overshooting.