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- Aviation Safety in History
- Debrief: Stick to the Basics: Aviate, Navigate and Communicate
- Self-Paced Study Program
by Peter Garrison, Contributing Editor, FLYING©magazine
On Christmas night, 2006, it was foggy in Lawrenceville, Georgia. Briscoe Field was reporting half a mile visibility in fog, with the ceiling at 100 ft, when a Cessna 414A arrived from Florida on an instrument flight plan.
The 44-year-old commercial pilot had logged over 400 of his 632 hours in the airplane in which his life and those of his two passengers were shortly to end. His actual instrument time was 26.4 hours; his simulated instrument time, 56.3. He had logged 142 hours at night. He was comparatively inexperienced, but current, qualified, and legal. Despite the festive date he was not, as toxicology tests would later establish, under the influence of alcohol.
As the pilot approached Lawrenceville, the controller advised him of the weather, which was below the airport minimums of 200 and one half. The pilot elected to attempt the ILS [instrument landing system] Runway 25 approach, as he was entitled to do: The criteria for landing are expressed in the FAR [U.S. Federal Aviation Regulations] as “flight visibility” because it is understood that what the pilot sees on final approach is not necessarily the same thing as is seen from the tower or from some other weather observation point. The pilot is on his honor not to descend below the minimum altitude unless he has the runway or its lights in sight.
The pilot missed the approach, but he reported to the controller that he had caught sight of the airport as he passed over it and wanted to try again. The controller vectored him back around to the approach course, and repeated the current weather conditions.
On the second approach, the tower advised the pilot that he was drifting to the left of the extended runway centerline. The pilot acknowledged. Shortly after, the tower controller saw a bright orange glow beside the approach end of the runway. He tried without success to contact the 414. It had crashed into an asphalt plant, clipping the tops of trees and striking a gravel berm before eventually coming to a stop 1 100 ft south of the runway, heavily fragmented, amidst the machinery of a rock crusher.
The NTSB [U.S. National Transportation Safety Board] neatly, if unhelpfully, summed up the probable cause: “The pilot’s failure to follow the instrument approach procedure [and his] descent below the prescribed decision height altitude.”
This is the kind of accident that the newspapers will describe with some such phrase as “The airplane crashed while attempting to land in fog.” The image conveyed to the lay reader is of the pilot feeling his way toward the airport and inadvertently bumping into something, just as a driver, creeping forward in dense fog and darkness, might, in a moment of divided attention, collide with an inconveniently situated tree.
To an instrument pilot, the picture is more complex. An instrument approach is not a matter of feeling one’s way. It is a mechanical procedure which, if executed rigidly, will end either in a safe landing or in a safe abandonment of the attempt. It goes without saying that if you follow the instrument approach procedure to the letter, you will not hit the ground. So how does it happen that pilots, even ones flying precision approaches in which both altitude and lateral position are continually displayed, so often crash in the vicinity of the approach end of the runway, particularly at night?
You seldom learn exactly what happened on a particular flight—unless the pilot survives—but you can imagine a plausible scenario. On the first approach, the pilot stops descending at the decision height, and overflies the runway. Looking down, he glimpses the runway lights, and possibly, if the fog is spotty enough, even discerns illuminated features on the ground—a pool of light around a windsock or in front of a building, airplanes parked on the ramp. After all, these things are only 200 ft away, and the visibility under the overcast is half a mile. It appears that with a little luck he ought to be able to land. So he comes around for another try.
But there is a big difference between vertical and slant visibility. The conditions are reported as 100 and a half—round numbers. Looking straight down, one is separated from objects on the ground by, at most, 100 ft of cloud and another 100 ft of moderate fog. It is easy to see lights through that much fog—easier, in fact, than to discern surface features in daylight. But a standard three-degree glidepath has a slope of nearly 20:1. To see the same lights ahead of the airplane would require looking through 2 000 ft of cloud and another 2 000 ft of fog. The same principle applies here as applies to the ground fogs that sometimes form in otherwise clear weather. It may be possible to see an airport clearly from above through a thin layer of ground fog, but if you try to land, you find yourself suddenly blind in the critical final instants of the approach and flare. Looking straight down and looking straight ahead are two quite different things.
Looking straight down and looking straight ahead
are two quite different things.
But the glimpse of the lights subtly alters the pilot’s behaviour. He knows that he just has to get close enough to pick up the first few runway lights, and he’ll be okay. He’s already glimpsed the lights. He’s almost there.
The second try is the dangerous one. He now knows how tantalizingly close his destination is, and the urge to descend just slightly below decision height—to violate his pact of honour with the system, but only by a little—is very strong. His passengers know too; they have seen the lights sweep past the windows; they expect that they will soon be on the ground. The arcana of minimums and decision heights are beyond them; they just know that this big, expensive, pressurized airplane and its instrument-rated pilot are going to get them home.
Because the successful completion of the approach requires visual contact with the runway environment, the pilot is now obliged to divide his attention between the instrument panel and the windows. This is not the ideal way to fly an ILS to minimums. In principle, the pilot’s attention should be on the instruments, and the instruments alone, until he has either broken out of the clouds or has almost reached decision height. At this point he looks outside. If he sees the runway or the approach lights, he lands; if not, he misses.
But fragmentary visual cues before decision height confuse the matter. The final approach to Runway 25 at Lawrenceville is unobstructed, but one reaches decision height three-quarters of a mile from the touchdown point and still far from the approach lights. One passes over a divided highway and alongside a railroad yard with a large, illuminated parking lot. It is not hard to imagine that in the same way that some drivers whose attention is diverted by a car parked on the shoulder of the road unconsciously veer toward it, a pilot searching for lights on the ground might unconsciously drift toward the large lighted area of the train yard, which lies like a magnet just to the left of the final approach course and barely half a mile from the threshold.
What has happened in this situation is that emotion has entered into the picture, and the pilot has exchanged the role of the robotic executor of a mechanical operation for that of the newspapers’ baffled motorist poking his way through pea-soup fog. The ILS cross-pointers are drifting awry, but the pilot is no longer looking for needles; he is looking for lights.
The pilot acknowledged the tower’s warning that he was left of course, but by then he was already too low and too far from the localizer. Lawrenceville has medium-intensity approach lighting without sequenced flashers. Perhaps he mistook a light on the asphalt plant for an approach light. On a three-degree approach at 100 kt, 16 s elapse between a 200-ft decision height and the top of a 50-ft tree. Sixteen seconds sounds like a long time, and feels long when you’re sitting in an armchair looking at the second hand on your watch. But for a pilot hoping for a gift on a Christmas night approach to minimums, torn between doing the right thing and descending just a little bit lower, it may not be enough time to change his mind.
This article is based on the National Transportation Safety Board’s report of the accident, and is intended to bring the issues raised to the attention of our readers. It is not intended to judge or to reach any definitive conclusions about the ability or capacity of any person, living or dead, or any aircraft or accessory.
Reprinted with permission from FLYING© magazine, November 2008. All rights reserved.
On June 19, 2008, a Eurocopter EC 120B helicopter departed Lac des Neiges, Que., on a visual flight rules (VFR) flight to Québec, Que., 42 NM to the south. Approximately 15 min after takeoff, the weather deteriorated and the pilot chose to land at Lac à l’Épaule, 28 NM north of his destination. While overflying the lake at low altitude to verify the chosen landing spot, the pilot turned on the demist hot air to clear the front windshield of condensation. The windshield immediately misted up, the helicopter lost altitude, and struck the surface of the water. The pilot and passenger sustained minor injuries and evacuated the aircraft successfully. The pilot helped the passenger towards the shore. They were assisted by two fishermen in a small boat and were then transported to hospital by ambulance. While the passenger initially survived, he subsequently died due to exposure to the cold water and intense stress. This article is based on the Transportation Safety Board of Canada (TSB) Final Report A08Q0110.
Weather conditions for the planned route were not checked prior to departure. Although the forecast was for mainly VFR weather, low patchy ceilings and precipitation were forecast for the area. The flight was to take place in a mountainous area where the cloud level would likely, at times, restrict free passage in some areas, especially over the elevated terrain. The pilot encountered unexpected conditions of reduced visibility in moderate to heavy rain showers in the vicinity of Lacàl’épaule that forced him to find a safe landing spot to wait for the weather to improve.
The pilot chose to execute the approach over the water. This allowed for a shallower approach and kept the helicopter away from any obstacles that might have been difficult to detect. It is not unusual to fly over a river or lake in conditions of low visibility. However, in the event of an unforeseen problem (such as an engine failure), the helicopter may not be within gliding distance from shore, thereby posing a risk to the aircraft and its occupants. Even if there was no place to land along the shoreline, if the helicopter had been flown closer to it, the risk associated with swimming long distances in cold water would have been reduced.When the pilot selected demist hot air to clear the windshield, the warm air from the ceiling ventilation ducting was instantly cooled when it hit the relatively cooler windshield. This rapid cooling caused the air to condense, and fogged the windshield and front side windows. The immediate fogging of the windshield and front side windows, combined with the heavy precipitation, restricted the pilot’s ability to maintain outside visual references. He did not have time to open the bad weather window, which could have given him some outside visibility. Without any outside visual cues, the pilot did not perceive that the helicopter was descending from 100 ft above ground level (AGL); the helicopter struck the surface of the water at low airspeed.
Map showing the trajectory and impact point of
the helicopter, which was proceeding towards
a cottage at the north end of Lac à l’Épaule.
Warm air can hold more moisture than cold air. Therefore, with time, the warm air entering the cabin via the ceiling diffusers would have allowed the temperature of the windshield to rise to a point where the water vapour contained in the warm air from the ducting would not transform into water droplets. At this point, the windshield would then start to clear. Therefore, had the demist been selected while flying at a higher altitude, it is likely that the fogged windshield would have cleared in enough time for the pilot to notice and to correct the descent prior to striking the water surface. No documentation cautions EC 120B flight crews about the risk associated with the selection of demist during certain critical phases of flight, which can, under certain weather conditions, cause a temporary loss of outside visibility and a loss of control of the aircraft.
Findings as to causes and contributing factors
- Weather conditions for the planned route were not checked prior to departing Lac des Neiges. The pilot encountered unexpected conditions of reduced visibility in moderate to heavy rain showers and low ceiling conditions, which forced him to land.
- The windshield fogged up immediately after the pilot had selected demist hot air. This, combined with the heavy precipitation encountered, restricted the pilot’s ability to maintain outside visual references.
- With the loss of visual references, the pilot did not perceive that the helicopter was descending from 100 ft AGL and the helicopter struck the water. The pilot did not have time to open the bad weather window, which could have given him some outside visibility.
Findings as to risk
- The approach for landing took place beyond gliding distance from the shore, which put the aircraft and its occupants at risk in the event of an unforeseen problem.
- No documentation cautions EC 120B flight crews on the risk associated with activating the demist system during certain critical phases of flight and under certain weather conditions; activating the demist system can cause a temporary loss of outside visibility.
- Selection of the demist system while flying at a higher altitude would likely have allowed the windshield to clear sufficiently in time for the pilot to notice and correct any undesired change in the aircraft’s flight parameters.
Safety action taken
Eurocopter has developed an Information Notice on the use of the demist system that was issued on July 15, 2009. This notice alerted all Eurocopter helicopter crews of windshield flash fogging that can occur in certain weather conditions when the demist system is activated, which could, subsequently, reduce visibility and temporarily create a loss of visual references. This notice reminded crews of the importance of using the bad weather window in such circumstances to ensure visual contact with outside references.
The day started off earlier than most; I was in to work with the sunrise as I had a long trip to fly a tech to Bella Bella, B.C., in order to fix a broken Cat. When I got there, the owner and his son were busy getting the C206 ready. They were less friendly than usual, but I put that down to the early hour. The owner’s son took off as I waited for my passenger to arrive.
My passenger arrives, we load up his tools, and take off. The trip is west across centralB.C., and over the plains to the coast. We will fly through the mountains, over Bella Coola, B.C., and on to Bella Bella. The weather looks okay for the trip, but there is no station at Bella Bella, so we will have to rely on any pilot weather reports (PIREP) en route.
I am a newly hired chief flight instructor (CFI) of a small school that also does single-engine VFR charters. My wife and I moved up here from Vancouver, B.C., and I had only 650 hr—mostly instructing time—before coming here. It has been a learning experience to say the least. I always taught my students by the book where navigation was concerned: fly the line, assess the deviation, and correct. VFR charters in the Cariboo call for a different technique: fly the line as much as you can, when you hit the weather, the choice is turn left or right to get around it and then get back on track. GPS with an ancient long range air navigation (LORAN) system is the preferred method.
The trip over the plains is uneventful; I have been out to Bella Coola a dozen times now and I know the way pretty well. My headphones crackle with the owner’s son’s typical greeting:
“Got your ears on?”
“Hey there. You were out of there so fast I hardly got the chance to say good morning!”
“They needed a fast flight,” he replies.
“Sort of; I’ve got a pickup.”
It turns out a young man had drowned in the river.
Bella Coola is a beautiful spot nestled in the Coast Mountains. After flying over what amounts to basically one massive clear cut in various stages of re-growth from Williams Lake to the mountains, we fly over a plateau and start to descend into the river valley. The town itself sits where three valleys meet, and the river flows on to the ocean and out to Bella Bella.
Three valleys on the coast make for some interesting winds and currents, as the owner’s son’s unlucky pickup discovered. Later we loaded the “hummer,” as the Air BC Dash 8 captain called him (for human remains). It was odd stacking other people’s bags around and on the wooden casket. Especially weird were all the locked gun cases of the many hunters who pass through the area. Death has many faces.
The son tells me the weather looks okay to Bella Coola, so I decide to keep going once I get over the town.
I am flying today with some extra pressure put upon me by none other than yours truly.
One of the perks of my job is that I get to fly a local businessman around in his own airplane—a fast, retractable single.
The week before, we had flown his plane over Bella Bella on a gorgeous day; it was the most fantastic scenery highlighted by the summer sun. After dropping him and his family off for a fishing vacation, I took his plane back home. Several days later, when I got the call to pick him up, I had to turn around because of bad weather over the plains—I tried left, then right, then overhead and got to 13 500 ft before deciding there was no way to get through. Such is the VFR world.
When my boss, a legend in the area with 40 000 hr (all VFR), picked him up the next day, he told me the weather out at Bella Bella was something he wouldn’t wish on his worst enemy.
I am leery of his words as we make our way past Bella Coola and over the ocean proper. The terrain in the area is very unforgiving with all the peninsulas and islands rising sharply straight out of the ocean. The only place to put the plane down in an emergency would be on one of the small beaches, and that would be a disaster due to the fact that any marginally flat area is surfaced with jagged rocks.
I am using the “greasy thumb” method of navigation. My GPS is no help now as it only plots a straight line to my destination, and with the ceiling just under 1 000 ft, a direct route is out of the question. My thumb very carefully keeps track of our position on the map as we have several sharp turns around terrain in order to stay over the water. This technique will save our lives.
We are flying in a tunnel. The terrain rises on either side of us into the cloud. Over water is the only way, and what I originally thought was an acceptable ceiling has diminished by several hundred feet. Visibility was good, but with the cloud coming down, it has reduced dramatically. We are in and out of thin areas of mist.
“This is stupid,” I say to myself. My companion reads my thoughts and confirms my feelings as he crosses his arms firmly and lets go a loud sigh. This will be his primary commentary for the rest of our flight. My mind is awash in conflict: “continued flight into adverse weather” versus “it’s not far now.” “Get out of this” versus “we’re almost there.” We have been dodging the mist for a half-hour now and, while for a time it stabilizes at 700 to 800 ft, it certainly does not improve. We have to descend as low as 400 ft at times to get under it. On we fly as the voices in my head continue to argue.
“Just two more bends and we are there,” I tell myself. Home free, almost. It will look really good that I made it and got this guy to his Cat—a brand new machine that is holding up a big project, and costing lots of money in downtime. The other pilot always makes it; my boss gets in no matter what.
We reach the final turn in our tunnel and hit solid cloud. Panic grips my chest like a bear hug. Get it turned around! I am on instruments as I bank steeply, 500 ft above the water.
The unthinkable happens: my attitude indicator topples. I instantly get the familiar taste in my mouth that I always got after wiping out on my dirt bikes years ago—it’s like exhaust fumes, but in reality it is pure adrenaline. “Fight or flee” is the primordial command; I force myself to fight.
“Fly, fly by the VSI,” [vertical speed indicator] is a term familiar to me from my instructing days at Boundary Bay, B.C.; it is put to good use here. We show a descent.
“Get that nose up! Not too much!” my inner voice yells at me. My old instructor Doug is beside me, ready to rap my knuckles if I break my concentration for an instant. He recently passed away in a car accident.
We are on our reciprocal heading and come out of the cloud. [expletive…]
“I’m heading back to Bella Coola,” I tell my passenger, trying my best to sound calm.
“That’s fine with me!” is his terse reply.
The nightmare is far from over though. We are 45 min away from Bella Coola. Coupled with the hour and a half it took to get to that town, this is turning into a very long flight. We have four hours of fuel total, so we will land with an hour in the tanks, provided the weather is still okay there. My major problem at this point is the several cups of coffee I had while waiting for my companion to arrive. I use the pain in my bladder to keep focused.
I always prided myself on the fact that whenever I had a bad dream I could just tell myself to wake up, and everything would be fine. There was no waking up from this flight though; I had to battle this to its conclusion.
Again and again we are in the mist, so we are up and down between 800 ft and 400 ft. Just when I can relax a bit, I hit more mist and must go down again. I carefully plot our position on the map and take us around the various peninsulas. Finally, we reach the coast again and land at Bella Coola. Land has never before—or since—tasted so sweet to me.
“I hope I didn’t scare you too badly,” I say to the Cat tech through clenched teeth.
“No, no problem,” he counters. He spends the next hour chain smoking outside the terminal as I wait to see if the weather improves. When it does not, we take the refuelled Cessna back to home base.
- To compare my abilities with another vastly more experienced pilot was extremely foolish.
- Turning back hurts the pride, but is never a wrong decision.
- Know thine own abilities, and know thy aircraft.
This account is a true event provided anonymously to the ASL for the benefit of all. Thank you.—Ed.
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