Lift can't touch this stuff
Some emergencies can be simulated to good effect without risk. You can don a pair of view-limiting devices to grapple with inadvertent flight into instrument weather and nibble at the queasy edge of spatial disorientation. You can take off from a long runway at less-than-full throttle to sample the effect of high density altitude on your engine's ability to make power--great training for next summer's cross-country from the lowlands to Santa Fe, New Mexico (airport elevation 6,348 feet msl). A safely executed simulation of engine failure by your instructor when your focus is on something else makes a lasting impression. So does a go-around commanded when you are lulled to think that you are about to snap off a nice landing. Stall recoveries are simulations of accidental stall entries and how to react, although this is not always explained to students who become wary of the maneuver out of ignorance of why it is being performed.
Today, the subject is ice, and some unfortunate occurrences that show how a pilot trained only to visual flying standards, in command of an aircraft with no equipment for dealing with it, must avoid it at all costs. Most training environments can't simulate ice's ability to wipe out normal controlability and power responsiveness of your aircraft, leaving you in command of a contraption that had not even been invented until you invented it by flying into the ice.
You could do perhaps a 40-percent simulation, limping around in slow flight with a view-limiting device balanced on your nose. Missing would be the weather that got you into the situation, and the sick feeling you'd get--or should, anyway--during your dawning awareness of what is happening as the aircraft tries to die on you in a slow, agonizing fashion. You wouldn't get to see the windshield and leading edges of airframe components crust over. You'd miss the perplexity of radios acting up. The prop might sound funny, or vibrate. Your pitot-static instruments could turn on you. And--was that a chirp from the stall warning? At 100 knots?
But you'd look down and see that you're not flying 100 kt. You're down to 80 or 75, despite cruise power, and your altitude is headed down too. This is confusing. The airplane never felt like this before. Time to get out of here. Of course it was time to get out of here long before this point, but reacting to tiny warnings isn't the way most pilot training goes. Engine failures are all-or-nothing events. Radio foul-ups reveal themselves in a characteristically peculiar silence. Even getting lost happens relatively quickly and doesn't alter the handling characteristics of the aircraft.
Student pilots learn that ice is brought on by an inadvertent cloud penetration. But you are a conscientious VFR pilot and didn't fly into a cloud. Then the culprit had to be freezing rain or drizzle. Are you sufficiently cautious about flying in the rain? While that may not be a bad call in itself, were you taught to keep tabs on the outside air temperature gauge so that the convergence of "visible moisture" and freezing temps could have been avoided?
So maybe it's just as well you can't simulate an ice-up. Wait a minute. There is another way. Simulate this. You are a non-instrument-rated pilot flying a Cessna 172 over Vici, Oklahoma, on December 3, 2002. This is your 100th hour of pilot time, and it is going to be memorable. The flight originated at Liberal, Kansas, en route to Oklahoma City. At departure, the weather conditions were noted in the National Transportation Safety Board accident summary as "light to moderate snow and 5-7 miles visibility." Things get worse. "Subsequently, the ice accumulated throughout the airframe and the pilot performed an unscheduled landing at Woodward, Oklahoma (WWR) to remove the ice."
Good move. But, "After the pilot partially removed the ice and obtained an update on the weather conditions via the computer, the flight departed Woodward for Oklahoma City." Not so good. Now things get interesting.
"During cruise flight, the pilot noted an indicated airspeed of 115 mph and the flight encountered freezing rain and structural ice which continued to accumulate. Within the next 20 miles, the pilot observed the indicated airspeed decrease to 100, then 90, and finally 80 mph. The pilot reported that he decreased the pitch of the airplane to maintain the airspeed at 80 mph and diverted the flight to the Vici Municipal Airport; however, the airplane was unable to maintain 80 mph, and the pilot elected to perform a precautionary landing to an open field short of the airport."
We'll get to the off-airport precautionary landing and the weather reported at a nearby station in a moment. Make note of that weather--it's a classic icing scenario. Imagine yourself experiencing that final 20 miles of flight. Airspeed decreasing. Airframe ice growing and distorting familiar airfoil shapes into grotesque, cartoon-image imitations. Pitching the nose down to maintain--yes, just to maintain--80 mph. Eighty mph is how many knots? About 69.5. Most of us use airspeed indicators calibrated in knots, so don't think about this joyride as taking place at 80 mph. Think about flying it at 69.5 knots. And still slowing.
Even the damage during the landing has to be counted as a blessing, considering the alternative. The NTSB report said, "During the landing roll in rough and uneven terrain, the nosegear collapsed, and the airplane nosed over coming to rest in the inverted position. The engine firewall sustained structural damage, a propeller blade was bent, and the top portion of the vertical stabilizer was crushed." The pilot was uninjured.
As for the nearest weather report, taken 30.4 nautical miles away at Gage, Oklahoma (GAG): "About the time of the accident, GAG was reporting calm winds, visibility 4 statute miles with freezing rain and haze, few clouds at 1,000 feet, a broken ceiling at 1,500 feet, and overcast at 2,800 feet. The temperature was 28 degrees Fahrenheit and the dew point was 27 degrees Fahrenheit." Consult your training publication discussions on airframe icing and you will see that this report fits the profile in all particulars. Official probable cause: "The pilot's departure and continued flight into adverse weather conditions. Contributing factors were the icing conditions, and the lack of suitable terrain for the precautionary landing."
How close was this aircraft to falling out of the sky? Very close, it is safe to propose. In support of this theory, consider the case of another iced-up airplane--this one unable to get off the ground. On December 20, 2001, the 1,700-hour commercial pilot of a single-engine Cessna 208B turboprop freight hauler removed snow from the aircraft using a ladder and broom as part of her preparation for an IFR flight from Auburn-Lewiston, Maine, to Manchester, New Hampshire. Weather reported at the airport at the time included "a broken ceiling at 100 feet with an overcast layer at 800 feet. Visibility was 1-3/4 miles in light snow. The winds were from 360 degrees at 4 knots," said the NTSB summary. It described the situation: "At 1955, the airplane taxied to the run-up area for a before-takeoff check. All operational checks were normal and in accordance with limitations. At 1958, the pilot obtained her departure clearance and was released for departure at 2000. At that time a second contamination check was conducted before she taxied slowly onto the runway due to unplowed conditions."
Cutting to the chase concerning the effects of icing: "The pilot began the takeoff roll and rotated the airplane when it reached 90 knots. The main wheels lifted off momentarily, then settled back onto the runway." And, "The takeoff was aborted, the power lever was placed in the Beta/Reverse range, and the brakes were applied. The airplane slowed, but continued its slide down the center of the runway. The pilot secured the engine before the airplane overran the departure end of the runway. Once off the runway, right rudder was applied to avoid the localizer antenna. The airplane veered to the right, and the left main tire caught anchor cables attached to the antenna. The airplane pivoted to the left, around the backside of the antenna, and came to rest."
The NTSB report noted that snow had continued to fall while the pilot cleaned the surfaces during her departure preparation. "The second contamination check was performed from the cockpit, just prior to taking the runway. Both the preflight and the before-takeoff checks were completed per the Cessna manual." The report also cited the Cessna manual on airframe ice: "No attempt should be made to take off with a load of ice or snow. Ice and snow on the wings will change the shape of the airfoil and disturb the flow of air over the wings, reducing available lift and airspeeds. Do not assume that light snow will melt or blow off during taxi-out or the takeoff run. Even if it does, it may reveal ice or frost beneath."
This scenario is set down here to illustrate the aerodynamic destruction ice can impose on an airframe. Whether the coating of ice is acquired by flying into it, or failing to clean it off, or reacquiring it--as both these flights did in different ways--the behavior of the underlying airfoils became unpredictable. If ice threatens your flight, land as soon as possible. On landing, treat your aircraft as if you have never flown that make and model before--because you haven't.
Dan Namowitz is an aviation writer and flight instructor. A pilot since 1985 and an instructor since 1990, he resides in Maine.
See the AOPA Air Safety Foundation for more resources on icing and wing contamination.
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