What Keeps Pilots Up at Night

Flying in the dark can play tricks on your senses.

grease pencil to note pallets delivered
The author uses a grease pencil to note pallets delivered to a cruiser in the Atlantic, where she deployed with Helicopter Anti-Submarine Squadron Light 46 in 2011.

When I was learning to drive, I remember how I savored the gently curving descent navigating Ship Road, lit only by our 1986 Saab’s headlights. “I love driving at night,” I told my dad, in the passenger seat beside me. “It’s so much more peaceful.” Ever the vigilant instructor, he responded: “That’s only because you can’t see the dangers at night. They’re still there.”

He was a nervous father, but also an experienced pilot. When I started Navy flight school, his words stuck with me.

Human eyes did not evolve toward seeing in the dark. Every pilot learns the basics: Your eyes contain rods and cones. You use your rods at night. Unlike cones, which are concentrated in the center, rods are spread out to the periphery across your eyeball.

Our peripheral vision comes at a cost to overall visual acuity and color perception. There’s spatial disorientation, closely followed by its scarier cousin, vertigo. The aviation term for the worst-case scenario that can result from these malefactors is CFIT—Controlled Flight Into Terrain.

Though I understood these hazards, once I’d earned my wings I couldn’t help but find night flying as peaceful as those dark Pennsylvania back roads. For one thing, the temperatures in the Middle East, where I deployed twice, are slightly more bearable at 2 a.m. than at high noon. Mostly, it was just quieter: Less chatter on the radios, more shooting stars. The darkness felt like a cloak against unseen dangers. I knew that sense of peace was not to be trusted, but I was grateful for it.

The military trains pilots to recognize physiological degradations to which we’re prone at night, but training cannot eliminate our evolutionary limitations. Every pilot has experienced vertigo or spatial disorientation. If you’ve ever stomped on the brakes as a result of car movement in the next lane at a red light, you’ve experienced spatial disorientation too.

I saw the 1979 entry in my dad’s logbook where he confessed to vertigo on an early training flight: “All you got to do is trust those instruments,” he wrote. This mantra is beat into flight students because it does not come naturally.

The first time I remember feeling vertigo was at the end of a flight on my first deployment. Our helicopter squadron would ordinarily practice takeoffs and landings at the end of a mission to keep up proficiency. I landed my SH-60B Seahawk, lining up with the white lines on the gray steel deck with no issues. Time for my next try.

It was nighttime: vertigo risk factor No. 1. It was the end of a three-hour flight. Fatigue: risk factor No. 2. I would “tactically dehydrate” before flights, because there are no bathrooms in helicopters. Dehydration: risk factor No. 3. My takeoff was normal, but maybe I turned my head too quickly to the right as I simultaneously pulled in power to climb. Multiple-axis inputs to the inner ear, whether you’re in a helicopter or on a roller coaster, can send your internal gyroscope spinning.

The pilot sitting next to me spoke up: “So are you planning on turning back towards the boat any time soon?”

I understood what was happening, but I couldn’t make my hands move the flight controls. The aircraft’s attitude gyro showed us wings level, and the altitude hold was engaged, so we weren’t in immediate danger. But I felt my insides flip-flop. “Feel like—already—in a turn,” I sputtered.

“I have controls” came the reply. I relinquished my sweaty grip on the cyclic stick, scanning my instruments as the other pilot turned us back on profile—a simple maneuver that felt like a barrel roll to me—to land on the flight deck and call it a night.

While technology has not yet defeated the false sensations experienced by pilots throughout history, it has helped us compensate for our human inadequacies: tools like altitude hold, Night Vision Devices (NVDs), and various collision avoidance systems all help us regularly cheat death.

I have a love-hate relationship with NVDs. They “turn night into day,” we’re told, which is true if during the day you see only shades of green and black and your field of view is limited to 40 degrees through two separate toilet paper tubes. There is also the weight of the goggles, which causes neck strain. They’re mounted on the front of your helmet, and a battery pack attaches to the back. Sometimes there’s a counterweight added to the battery pack to keep the goggles from slipping. The rig weighs more than two pounds, which doesn’t sound like much, but I challenge you to balance a bag of flour on your head for three hours and move your head constantly. Hot spots may also develop from your helmet, and you can get headaches if your focus is off by even a little.

The alternative to NVDs is spatial disorientation or worse, and goggles may have saved me one night just outside the Arabian Gulf. We usually donned NVDs for the takeoff from the boat, but then I customarily asked the crew to take them off until landing for my own comfort. Either the entire crew wears NVDs or no one does, to prevent confusion. After weeks of patrolling the same square of ocean, we all believed there was nothing out there for us to see.

I might have interrupted my crewman sneaking a nap in the back when I shouted something about an aircraft directly off our nose. I announced a descent to avoid a collision and bottomed the collective control, setting a hard deck of 500 feet. Once we leveled off and my breathing slowed, my copilot and I realized I had dumped altitude to avoid the mast-lights of a container ship. At sea level, obviously.

I’d fallen prey to spatial disorientation, specifically autokinesis, the perception of fast motion in a distant, stationary (or slow-moving) light source. In letting my bored gaze focus on a single light source at the center of my vision, I had enabled the light to appear to move. Forewarned, it turns out, does not always equal forearmed.

Between the training and the tools, U.S. military pilots should be masters of the night skies. Before every flight we brief the same checklist items. When we get to “Vertigo/Spatial Disorientation,” every Navy helicopter pilot recites something close to this: “If any crew member even thinks they have vertigo, confess it. If it’s the flying pilot and we’re in a critical phase of flight, swap controls. If both pilots have vertigo, engage altitude hold and both verbalize control inputs. For spatial disorientation, if anyone is at any time unsure of where we are or what we’re doing, speak up and we’ll discuss it as a crew, using all the tools we have available to us: instruments, charts, radar, checklists, until we get our situational awareness back.”

CFIT is harder to brief or plan for, since it is the result of a chain of sensory illusions. On the wall of some flight briefing spaces you’ll find a sign that lists the basic rules of flight:

1. Try to stay in the middle of the air.

2. Do not go near the edges of it.

3. The edges can be identified by objects such as trees, buildings, cars, etc.

The levity of the expression belies the gravity of the message. On the day of my first flight in a Navy aircraft, another aircraft in my squadron flew into a mountain in northern Alabama. Both student and instructor were killed.

With all of the technology and training available to us, the best way to avoid crashing a perfectly good aircraft at night is to have your confidence shaken early. Not destroyed, but shaken. Just enough to remind you to trust your instruments. And when you land, after one of those inevitable scary flights where you couldn’t trust your senses, remember to tell Dad he was right.

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This story is a selection from the August issue of Air & Space magazine

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