FLIGHT INTO KNOWN ICING

© 1991, Clayton Davis

(First published as "The World Will End In Ice" by Plane & Pilot, Dec, '91)

----- Don't ever let the reason for making a flight become more important than the flight itself. Getting there is the most important part. If you can't, you can't. -----

It snowed February 18, 1977, at Joe Zerbey Airport in Skhuylkill County, Pennsylvania, eight miles west of Pottsville, a small town of 25,000 people. I am estimating the number of people living there, and don't know yet why they named the airport for him.

It probably snowed, or much worse, at Summersville, West Virginia, less than two years later on January 29, 1979. I did not manage to land that day at the airport with the same name as the town only four miles to the north, population less than 2000 citizens.

These dates are highlighted in my logbook, because the same passenger wanted to charter the same kind of airplane on both dates to visit his coal mines. I was flying for Baltimore Airways during those years. This distinguished, gray-haired gentleman who owned the coal mines requested my company send me along whenever he chartered an airplane. But why visit coal mines in bad weather? Why did he want me to fly him?

He said something about the confidence factor. True, I would fly anything, anywhere, anytime, it seems now.

Baltimore Airways assigned pilots individual callsigns, consisting of a number and the abbreviation BALTAIR. My pilot number was 143. Therefore, my personal callsign was BALTAIR 143. The gray-haired Baltimore businessman preferred to call me Captain Clayton. I think the president and founder of Baltimore Airways had been accustomed to tactical callsigns in the military, thus he called himself BALTAIR ONE. Seemed reasonable to me.

We flew to Pottsville, Pennsylvania, in an airplane named for the Seneca Indians, built by Piper Airplane Company. For years Mr. Piper named them all after Indians, except the first one, the sweet little, gentle, yellow Cub.

Just as all cameras were Kodaks(R) to laymen, everything low and slow enough to be seen was a Piper Cub, still is to many folks out beyond the suburbs.

Airplanes used for commercial flying all year round must be equipped with ice protection devices in two broad, general areas. The very first thing protected must be the Pitot tube. At the same time, hopefully, the designers install protection for Fuel Vents and Stall Warning sensors. Right along with Pitot tube protection, we place propeller anti-ice in our first category.

The Pitot tube was developed by a person named Mr. Pitot, pronounced Pee-Toe. As the airplane is moving forward, speed is registered when air pressure in this tube increases. Any ice in this tube deprives a pilot of airspeed indication. This kind of flying becomes interesting, when you don't have any idea how slow or fast you're moving through the airspace.

When fuel is drawn from the airplane's tanks, air is permitted to fill the space within the tanks. The vents through which this air enters must remain clear of ice. If you are unable to replace the air in the tanks, no fuel will flow. When that happens you become a glider pilot.

There are several ways to sense a condition of airflow diminishing over the wings, however, any small amount of ice will interrupt whatever delicate engineering arrangement that was installed to give warning of an impending stall.

Now picture this, but don't practice it. Your Pitot tube has iced up and you have no idea how slow the airplane is flying. Ice begins to cover the leading edge of your wing. Right away the stall warning sensor stops sensing. Then the fuel vents ice over. Your engine is hungry, pouts, then resigns, won't utter a sound in your defense. You are probably flying inside a cloud, gradually collecting rime ice.

Film at eleven; the newspapers do their best to tell everyone what an experienced pilot you were, how many civic contributions you made in the community. But ice is guaranteed to form and weather forecasters gladly tell you where and when to expect it. All that experience the newspapers said you had, but film at eleven.

Propellers, Pitot tubes, vents and sensors are protected by wrapping them with heating elements, using current from your airplane's electrical system. Look at the load meter when all of them are turned on. Remember how warm an electric iron gets. Read the Pilot Operating Handbook that came with the airplane and decide how much electrical load the system can support.

Getting into some serious ice requires de-ice boots, and we need to protect the windshield. Actual blind landings are very interesting.

These last two items are the second category or level of protection. The first group are designed for anti-ice work. That means you keep it from forming. The last group removes ice, thus are called de-ice.

Nothing can be installed on an airplane that will permit flight to continue. All are designed to let you escape from ice. There are two directions you can go, up or down. You can not go around. When conditions are right for ice, it forms. It is found in clouds. Descend through them and land, or climb out on top.

There is a third place you can go to escape. It is based on a temperature forecast. If warm air is overriding cold air, in a warm front, you will find a level where the temperature warms slightly. Whether it gets as warm as you need may sometimes not happen. Then again, when cold air is overriding warm, a cold front for example, there may be a warm place down lower. But you absolutely must know where your escape route lies. Don't make an icicle out of your flying machine.

Perhaps as important as knowing where to expect icing is the decision to launch a mission in an airplane not equipped with all items installed and working, either anti-ice or de-ice.

Our flight to Pottsville's Joe Zerbey Airport was in a Seneca airplane with no de-ice boots on the wings and tail leading edges. Warm air was overriding cold air between Baltimore and Pottsville on February 18, 1977. This meant we could expect the temperature to drop as we climbed to 4000 feet altitude, then a rise slightly. All other things being equal, temperature decreases two degrees centigrade for every thousand feet of altitude.

Outside air temperature gauges are circular instruments no bigger than a half-dollar coin, with Fahrenheit on the outside scale, Centigrade on the inner ring. The inside scale is notched every two degrees. Watch it during the climb. Every thousand feet will give one notch, or two degrees decrease, down to zero. At zero degrees centigrade ice begins to peel off windshields and other places, as you climb into warm air. Just above zero degrees centigrade, at plus-two for example, the airplane stays clean. No ice will form.

Harrisburg and Reading were forecast to have light snow, while Baltimore would remain partly cloudy with bases 4000 feet and wind from the southwest. Pottsville, having no weather reporting service, could expect conditions similar to stations nearby. As we climbed through 4000 feet, the temperature went positive and the clouds became overcast to broken.

The approach to Joe Zerbey Airport used Ravine VOR (VHF Omni-Directional Radio Range), and as a cross-check there was a Non-Directional Radio Beacon (NDB) located on the airport. Harrisburg Approach vectored us to intercept the VOR inbound track about 6 nautical miles from Ravine VOR. We had already been cleared for descent to 4000 feet. As the VOR display needle became sensitive, Harrisburg cleared us for the approach, with instructions to change to advisory frequency and to report back to Harrisburg should be miss the approach.

Joe Zerbey Airport sits on the top of a hill 1730 feet above sea level. With our altimeter set for the pressure at Harrisburg, we crossed "Hegin" intersection 8 nautical miles northeast of Ravine VOR at 3300 feet. It was all downhill from there.

Minimum descent altitude for a circling approach is 2360 feet, if the local altimeter setting is available. We had changed to the advisory frequency to call Zerbey and were told the wind was favoring landing on runway two-nine. The airport manager also gave us his local altimeter setting.

Travelling at 120 knots indicated airspeed, we expected to see the airport two minutes and thirty seconds after passing Hegin intersection, if we were down to 2360 feet altitude and clear of clouds.

Descending below 4000 feet dropped the outside air temperature to minus-one degree centigrade. We entered very light snow with propeller heat and windshield defrost already turned on. My escape plan was to climb back into warm air, should we begin to accumulate rime ice. Light snow usually will not stick to the airplane's surfaces. However, flying inside clouds with below-zero centigrade temperatures produces rime ice.

At 2360 feet with the VOR display centered and the NDB needle pointing at the airplane's nose, when two minutes and thirty seconds had passed I saw a hill with the top scraped off about six hundred and fifty feet below our nose. We told Zerbey Airport we were entering left downwind for a circling approach to runway two-nine.

My passenger still had not seen the airport, but was willing to land on top of a hill if I was certain this was the place. He was expecting to see the runway with a nice centerline painted down the middle. Covered with light snow, it looked like a road 4580 feet long sitting on a hill in the middle of Pennsylvania.

A jeep took my passenger down the hill someplace, while I watched it snow and visited with the airport manager. Every thirty minutes I borrowed his broom and swept the wings and tail surfaces clear of snow. Less than an inch of snow lay on the ground. It was dry powder and loose. I wanted to touch the airplane's surface with my bare hands and know I was feeling metal, not a coating of ice.

Two and a half hours later my passenger returned and asked if I felt good about the flight. I told him only the windshield bothered me, because there was no propeller slipstream to clear it when we began our takeoff roll. He asked how much time I needed after clearing it one last time. I suggested we roll into position on the runway, and if he agreed, open the door and brush the windshield clean for me. The door was on his side. No problem, he used a file folder from his briefcase and returned to his seat. As he closed the door and fastened his seat belt, I held brakes and brought up engine power.

Our clearance received over the telephone had a void time with permission to climb on course to 6000 feet. As we climbed through 4000 feet, the outside air temperature went to the plus side of zero centigrade, relieving us of any concern about ice. Baltimore was comparatively "hot and dusty" for our arrival.

Considering a flight such as this with only rime ice in the forecast, I will launch an aircraft that only has Pitot heat and propeller heat, the anti-ice protection. The Seneca aircraft we took to Zerbey Airport only had this lowest level of protection against ice. The windshield was bathed in warm air from the defroster. Even though this gives very little ice protection, the warm air across my brow always cheers me up. My biggest weapon of defense was the knowledge that escape was available by simply abandoning the approach and climbing above 4000 feet.

Now we move forward nearly two years to January 18, 1979. The forecasted weather for the West Virginia hills between Elkins and Bluefield guaranteed, "Light to moderate, mixed clear and rime icing." No pilot reports were available. Friends and neighbors, fellow pilots and beloved countrymen, I beg you, seek to avoid these conditions.

Flight at 8000 feet kept us on top and talking to Washington Center until passing Elkins VOR. From there on it was all downhill. Clarksburg Approach was our host. They are located about twenty-five miles northwest of Elkins Airport. The clouds below us were dark blue, giving the appearance of a troubled sea in the early morning hours. My passenger had brought his son-in- law, the attorney, who wore a three piece suit. He sat in the back seat reading a law book.

He was becoming familiar with West Virginia civil law for the meeting in Summersville that day. Those clouds with the deep blue hue beneath us, looking like an ocean full of water, lay between us and his opportunity to practice law on his father-in- law's behalf.

Don't ever let the reason for making a flight become more important than the flight itself. You must arrive at your destination in order to fulfill your reason for going. Getting there is the most important part. If you can't, you can't. I advised the gray-haired businessman to expect some turbulence and a little ice. Furthermore, if it began to look like "we can't get there from here," I had two plans.

Plan "A" was to climb back on top. Plan "B" was to make the approach into Elkins where they were reporting 34 degrees fahrenheit on the surface. I had launched into these conditions with both groups of ice protection installed and working, anti- ice and de-ice. I was betting de-ice boots could break enough ice for me to complete the non-precision approach to Summersville Airport, West Virginia.

It must have been the "moderately clear" ice that accumulated with such enthusiasm that my attention was strongly focused on the de-ice boot operation, while keeping manifold pressure at climb power setting, and worrying about occasional light buffeting on the fail surfaces. I completely abandoned any thought of attempting an instrument approach into Summersville Airport.

Perhaps I could have tracked the published inbound course north from Rainelle VOR well enough to make the required descent into a beautiful valley carved by the Gauley river, then land on 3020 feet of paved surface. But my concern was occupied with the condition causing those innocent clouds to look so blue in the early morning light. They were filled with super-cooled water.

Water at 31 degrees fahrenheit, just below freezing, is called super-cooled water by meteorologists. It is looking for a surface to cling to, usually finding houses, barns, roads and bridges, forming sheet ice. This causes early morning radio announcers to be late for work and wise old pilots to stay home. This kind of water will gladly grab any innocent airplane wing that is dumb enough to visit it.

A front was passing through, not a big bad front, just a small one with air pushing up and over the hills. Folks on the ground saw light snow and sleet. Some warm air was still trapped in the Elkins Airport area, leaving the surface temperature at 34 degrees, but causing dense fog, zero visibility, zero ceiling.

Climbing back out on top, my plan A, was canceled because all power available was necessary just to stay afloat. Downhill was my only choice. Elkins asked us what were our intentions.

If traffic permitted, I reported, we would like to make a practice ILS approach to the Elkins Airport. I further added a pilot report and my guess that somewhere between Final Approach fix and Decision Height we would enter warm air and shed our ice. They cleared us for a practice ILS and wanted to know what would be our destination following missed approach.

I suggested we might want to go back to Baltimore, after they cleared us to climb back on top. My passenger said he could do some business in Charleston, West Virginia, so we requested Clarksburg to coordinate with Cleveland Center. We flew into progressively more clear conditions from Elkins to Charleston, because the front had already passed them.

But we did pick up more ice on the way to Charleston. While waiting four hours for my passengers, I asked the fuel attendant to witness my display of ice on the unprotected surfaces. He found another person to help swear to it. Both agreed it was four inches thick and shook their heads in amazement.

When I filed a flight plan for the return leg to Baltimore, I asked for any pilot reports in the Elkins area. A Seneca airplane had reported, "Light to moderate, mixed clear and rime icing."

I knew that already. Because, after all, it had been me making the report. Perhaps we had been the only air traffic in the area. Had we gone where nobody else wanted to, on that early morning flight?

The son-in-law attorney never again would fly in small airplanes. The Baltimore businessman was not bothered by any of the decisions we made and continued to use charter airplanes. I agree with the son-in-law attorney, because small airplanes are not my first choice for flight into extreme weather conditions.

A word of caution. Some private owners of small aircraft may read such accounts as this given here and decide to buy a rather sophisticated and well-equipped small airplane.

Of course, they will attend the factory approved training course required by the insurance company. Then they may think they can risk flight into known icing conditions. While many airplanes are equipped for such flight, some pilots, especially private owners, are not equipped for that kind of flying.

And please, don't request some professional airplane driver to accompany you on similar flights, thinking that will substitute for your lack of experience. Either fly your machine every day for at least a year as a working pilot, or hire somebody to fly it for you. Otherwise, there is a very good chance your beautiful airplane will return to earth unexpectedly.

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