DON'T WALK OUT... Stay in the Prime Search Area

Walking, they say, is as good as running. But not always. If you're trying to stay in shape, walking can indeed be as good as running. But if you're trying to get your shape back to the jungle we call civilization, walking can be hazardous to your health.

Years ago, when luckless aviators found themselves contemplating a wrecked biplane zillions of miles from the nearest outpost, they had no choice but to walk out. After all, they had just totalled the only aircraft in the area. And without a homing pigeon, they had no way of telling anyone where they were, and what had happened to them. So, back in the early days of aviation, walking out was de rigueur.

But it was at least 40 years ago when such teaching went out of style. With the advent of SAR forces, radios and, more lately, ELTs and satellites, the advice is to stay with the aircraft.

Why? Because when SAR starts looking for people, it goes to the last known point, then follows the proposed track. Although they're really looking for the people inside the airplane, they have long since learned that the aircraft is easier to see than the people. Thus the search tends to concentrate on that area between the last known point and the proposed destination.

The search isn't confined to that area, but it does start there, and initially concentrates there. During the search, SAR and CASARA crews look for anything unusual. You might think that a person wandering through the woods in a passionate purple T-shirt and bright yellow stretch pants would stand out, but such targets are pretty small. Even the larger remnants of, say, a single-engine Cessna or Piper are hard to see. But they are bigger than the average person.

Thus, SAR organizes the searches to find the downed aircraft. What does this mean to restless campers who think that walking out is showing admirable initiative? Unless they are retracing their proposed flight route, it means that they are moving away from the primary search area; away from possible detection.

Once in a very long while, there is a good reason to move away from the crash site. If the aircraft slides underwater, you don't want to sit in the middle of the lake for too long, amusing the fish. But you shouldn't go much farther than the nearest shore. If you're in the middle of a large forest fire, you'd probably want to move smartly to the upwind side. If you're surrounded by opposing factions in a hot war, walking — even running — out becomes an option. And, if you're in the middle of a Tyrannosaurus Rex family reunion, walking out could suddenly be an idea whose time has come. Better the idea's time should come than yours.

Failing any of the above, you might as well stay with the wreckage. If you can get at the ELT, move its function switch to ON. Then leave it there. The SAR tech who comes to your rescue can make any further switch selections.

Of course, you want to make yourself visible to SAR or CASARA crews. During the day, smoke gets attention. Your campfire, covered with pine boughs, will have local environmental wallahs on your case in no time. You can also add a touch of oil from the engine crankcase, just to make the smoke smokier.

Shiny bits from the aircraft can make signalling mirrors that you can flash into the SAR pilots' eyes. Or, as one pilot did recently, you can arrange larger chunks of aircraft in a nearby clearing to make it show up better for airborne searches. This isn't always an option, as Providence does not scatter nearby clearings to order, but it did work a few weeks ago.

Search efforts taper off at night, as SAR crews are not wild about flying into mountains. However, there are overflights, and most pilots are pretty good about reporting fires in areas where no fires had trodden before. Thus, an especially exuberant fire should get attention. However, you should take precautions to prevent being a feature attraction in the Great Forest Cook-off.

If you're an incorrigible Type A and think you must walk out — don't. Not unless you can see the lights of a nearby town, and the road connecting you to it. Even then, remember that distances are deceiving. If you must leave, leave a message of some sort. Let SAR know that you survived, and that you are walking northeast to salvation.

Salvation is fine. Too often however, it becomes eternity.

Stay with your aircraft.

Originally Published: 1/1997
Original Article: DON'T WALK OUT...Stay in the Prime Search Area

Controlled Flight Into Terrain (CFIT) — The "Why" is Never Easy

On June 1, 1994, the Swearingen Metro II had completed a MEDEVAC from Coral Harbour to Churchill and was returning home to Thompson, Manitoba. The pilot was flying a localizer back course approach when the aircraft sliced through the HOTEL non-directional beacon tower (NDB) that marked the final approach fix (FAF) at Thompson. The aircraft was in a wings-level attitude but only 62 feet above the ground when it hit the 87-foot tower. It was over 800 feet below the published beacon-crossing altitude and almost 300 feet below the minimum descent altitude (MDA) for approach.

The impact tore five feet off the right wing. The right prop ripped a tower support cable, toppling the tower to the ground. As the aircraft hit a second transmission tower, it rolled steeply into the ground. Both pilots died instantly. The MEDEVAC nurse, who was resting in the back, was thrown from the wreckage and, although severely injured, survived.

The captain was a very experienced 20,000-hour pilot with over 3000 hours flying MEDEVACs on the Merlin II. The first officer had almost 4000 hours flight time.

Why did this experienced crew fly into the ground?

The TSB investigation (report A94C0088) "determined that the flight crew lost altitude awareness during the approach and allowed the aircraft to descent below a mandatory level-off altitude." Among contributing factors cited in the report were "deviation from published approach procedures, ineffective in-flight monitoring of the approach, and pilot fatigue."

The first officer was in the left seat at the time of the accident and was the pilot flying (PF) (his grand total in the left seat of a Merlin was three hours). Over the two-week period leading up to the night of the accident, he had been holding various standby duties, accumulating 180 hours of standby. He had flown on nine of the 14 days on 19 separate legs totalling over 40 hours of flight time. Several days prior, he had been awake for 36 continuous hours. He had expressed concern to friends about the stress he was under.

A few days prior to the accident, his efforts to secure employment with a scheduled air carrier had fallen through. Friends noted an out-of-character mood swing — discouragement, irritation and increased anxiety.

At the time of the accident, he had been awake for 17 hours and on duty for 9 ½ hours.

The captain was fresh off an extended period off duty, but at the time of the accident had also been awake for about 17 hours.

The weather forecast called for 800-foot ceilings with visibilities of six miles, occasionally lowering to two miles in fog. The official observation, taken just prior to the accident, reported a 1200-foot ceiling with 15 miles visibility. The expectation of being in visual conditions may have caused the crew to relax their procedures. However, fog was rapidly developing northeast of the airport, and the crew may not have been in visual conditions when the accident occurred. Weather conditions, forecast or actual, do not, however, justify being more than 800 feet below the published beacon-crossing altitude when conducting an IFR procedure.

In reconstructing the aircraft's flight profile, TSB investigators determined that the crew could not have flown the published procedure but had flown direct to the FAF. The aircraft was in a high-rate descent when intercepting the localizer just prior to the NDB. Both pilots were coping with a high workload.

In the right seat, the captain was performing the duties of the pilot-not-flying (PNF). However, his instruments were not set up to effectively monitor the approach. Although the ILS frequency was dialled in, neither the course setting nor the heading bug were set. Nor was the altimeter set to station pressure. In addition, the altitude alerting system was found set at 5400 feet — it was either never set to assist the pilots in their descent, or it had been cranked up to an arbitrary altitude to deactivate it so that the bright yellow light and aural warning would not distract them during the final approach.

The last altitude warning available to the crew would have been the radar altimeter. It was found set to MDA and the warning light was ON at impact. However, the light is located by the pilot's right knee and may not have been part of the pilot's normal instrument scan prior to passing the beacon inbound. In the high ambient noise of the Merlin cockpit, the audio warning, a pulsating 80-decibel sound, would have been barely audible to the crew wearing headsets.

The insidious factor in this CFIT accident is fatigue.

The accident occurred after midnight and both pilots had been awake for 17 hours and on duty for 9 ½. The pilot flying had been holding standby duties for extended periods. His sleep patterns had been disrupted by issues related to both the job and his personal life. He was operating with elevated stress levels. Even for the captain, 17 hours awake would alone have induced some level of fatigue.

The combination of circadian rhythm, hours awake and workload placed both pilots in a fatigued state. A tired person is more likely to take risks. His or her performance of cognitive and vigilance tasks is impaired. Failing to perform the routine, or taking a shortcut, are much more likely than when a person is refreshed and alert.

Originally Published: ASL 1/1997
Original Article: Controlled Flight Into Terrain (CFIT) - The "Why" is Never Easy

To the letter

Keen-eyed Readers Comment on Monocular Vision

Dear Editor,

I refer to the article entitled "Through the Mountains" on page 6 of Aviation Safety Letter 4/97. I was a monocular-rated private pilot for approximately 20 years. Two years ago, I had laser surgery on my offending right eye. Now, albeit with the aid of glasses, I can qualify for a slick new commercial licence.

When flying or driving, I see virtually no difference from my vision before the surgery. When I do see a remarkable difference is during a rare visit to the grocery store. While walking down the aisles with the huge banners strung about, I finally do see in 3-D, or while in a forest with branches all around or during my first visit to the Skydome after surgery, again, I see in 3-D.

Where I feel our fellow aviator went wrong was with his map-reading ability. Map reading is an art. Not many people possess this seemingly simple skill. Of course, it does help to have a decent map! Usually pilots, as they get older, slowly start to lose their precious vision, whereas, because of modern technology, I have rapidly improved my vision and can now compare the two kinds of vision. Thanks for a really good Safety Letter.

Bob Wilson
Pickering, Ontario

Dear Editor,

I would like to comment on the "Through the Mountains" article in ASL 4/97. It is very far off the mark and certainly misleading. The accident involved a monocular pilot, and the article appears to suggest that the pilot’s visual handicap contributed to the accident.

In fact, it must be understood that human eyes are only binocular for a focal length of approximately 40 to 50 ft. This is because of the proximity of the eyes to each other, a distance averaging only 2.5 to 3 in. Beyond 40 ft., a monocular and a binocular pilot see the same monocular image because the angle of convergence is more acute the farther you are from the source being viewed. In effect, there is no binocular depth perception beyond 40 ft., even with two perfect eyes. Both pilots would see and use the same perceptive visual clues, but not binocular ones. Furthermore, the ability to perceive visual prompts when flying into the sunlight has nothing to do with whether the pilot does so with one or two eyes. The same goes for map reading. The problem was pilot error, for sure, but not a visual handicap.

The question of landing procedures for monocular pilots is another myth requiring debunking. The visual clues used by monocular pilots are different only close to the ground and, in fact, monocular pilots appear to have the advantage as their clues are less sensitive to the visual illusions so well documented with normal-sighted pilots. My own experience is that, in a learning environment, monocular pilots have a much better spatial awareness and consequently learn to land the aircraft in less time than the average binocular pilot does.

The only time truly monocular pilots (as opposed to those rated monocular but having normal peripheral vision) are impaired is in the area of peripheral awareness. However, pilots suffering such an impairment are very aware of their condition and compensate accordingly, even when not flying. In fact, a study of aircraft incidents will reveal that there is little difference on safety issues between monocular and binocular pilots and, corrected for percent head of population, monocular pilots would appear to have the better record.

It is clear that the accident had no relation to the pilot's monocular rating and it is regrettable that such should have been introduced into an otherwise excellent report. I hope that you may find it appropriate to offer editorial comment to correct the misconception.

Thomas R. Sommerville
Guelph, Ontario

Editor’s comment: The Transportation Safety Board’s final report on this accident (A94W0157) concluded that, although the pilot was monocular, this was not considered to be a factor in the occurrence. In addition, our Civil Aviation Medicine staff agree with Mr. Sommerville’s comments. Thanks to our readers for these eye-opening remarks.

Originally Published: Aviation Safety Letter 02/1998
Original Article: To the letter - Keen-eyed Readers Comment on Monocular Vision