By the time this magazine hits your mailbox, winter will be full-on in most parts of North America. Even if you spend most or all of your time in a warmer climate, your weather will change, with cooler temperatures, more wind and the occasional low-lying clouds, with rain. In other parts of North America, you'll likely experience the full range of winter's offerings sooner or later this season. Good luck.
Of course, winter's colder temperatures and denser air mean enhanced aircraft performance, at least when compared to summer's typical heat and humidity. But the season brings its own set of aircraft performance challenges, especially when it comes to precipitation. This time of year, moisture from the sky can come in many different forms, not all of it liquid. And an airplane doesn't have to be airborne to be affected; merely parking one outside in winter precipitation can have a major impact on flight operations.
Recent advances in technologies and equipment mean more and more personal aircraft are going aloft in conditions conducive to airframe icing. The good news is many of them are equipped to deal with the challenges. And, even if the only weapon in your arsenal against in-flight icing is a warm pitot tube, pre-flight and in-cockpit weather data is better than ever (see the article beginning on page 8), giving an increasing number of operators the critical information with which to make an informed decision.
Before we get to cruise altitude and settle in for the long slog home for the holidays, we still have to ensure the airplane is ready for the flight. This can be quite a burden if it's outside, the wind is howling, the thermometer hasn't seen shirtsleeve weather in weeks and your gloves are too thick to permit an adequate pre-flight inspection. You'll just have to tough it out.
Especially at airports where deicing equipment may not be available, you may not be able to adequately clean the airplane of all ice, snow and frost without heroic efforts. One way to address this problem is to leave the airplane in a heated hangar until the last possible moment before takeoff. If you ever thought doing so wasn't necessary, or was something "real pilots" don't do--they just kick the tires and light the fires--here's an example of one who perhaps thought that way, too.
BACKGROUND
On December 10, 2007, at about 0755 Mountain time, a Beech King Air 200 collided with a hangar about five minutes after takeoff while attempting an emergency landing at the Lemhi County Airport, Salmon, Idaho. The commercial pilot and the passenger in the right front seat were killed in the accident; two other passengers were uninjured. The airplane was destroyed by the impact and the post-crash fire. Snow was falling at the time of the takeoff.
When the first passenger arrived about 0700, the airplane was sitting on the ramp in front of the hangar. Light-to-moderate snow was falling. Soon, all passengers had arrived, the airplane was boarded and the pilot began taxiing. According to the surviving passengers, the pilot performed an external walk-around inspection. They stated he did not seem to take any more time doing his external inspection than they were used to him taking, and they did not hear or feel anything that sounded or felt like the pilot scraping or sweeping snow or ice from the airplane. One of the surviving passengers later remarked that when the engines were started it appeared that the propeller blast blew snow off the upper surface of the wing.
At 0747, the pilot requested his IFR clearance. The takeoff roll was estimated to have begun between 0748 and 0750. The pilot did not make post-takeoff contact with ATC.
According to the surviving passengers, the takeoff was normal, except the ground run seemed longer than usual. The airplane then lifted off, momentarily touched back down, and lifted off again. Almost immediately, the airplane rolled into a steep right bank. The angle of bank was severe enough the surviving passengers thought that the wing tip might contact the ground. After several such excursions from steady flight lasting at least 30 seconds, the rapid banking began to diminish.
The pilot made a left turn of about 180 degrees to parallel the runway. During this turn the airplane reportedly again rolled to a steeper than normal bank angle, but the pilot successfully rolled out on what was essentially a low-level downwind. When the airplane was about 1/4 mile south of the departure runway threshold, the pilot turned left toward the runway. The airplane began to sink at an excessive rate until it struck a hangar approximately 1300 feet southwest of the runway's approach end.
INVESTIGATION
The 0755 automated aviation surface weather observation (Metar) for Salmon indicated calm winds, one statute mile visibility, an overcast ceiling of 1600 feet, a temperature of minus six degrees Celsius, a dew point of minus eight degrees Celsius, and an altimeter setting of 30.04 inches.
The airframe, entangled with both the steel beams and siding of the hangar, came to rest in a nearly upright position aligned generally to the north. All major components of the airplane structure and flight control system were identified at the scene, although much of the fuselage was consumed by the post-impact fire. Nevertheless, correct empennage flight control and trim tab movement were confirmed when the control cables were hand-manipulated from a mid-cabin location. Neither engine displayed evidence of any pre-impact malfunction or anomaly that would have prevented them from producing their full rated power.
PROBABLE CAUSE
The National Transportation Safety Board determined the probable cause of this accident to include: "An in-flight loss of control due to the pilot's failure to remove ice and snow from the airplane prior to takeoff. Contributing to the accident were the pilot's improper preflight preparation/actions, falling snow, and a low ambient temperature."
There simply isn't much to add to the NTSB's finding, except to note this King Air was relatively light and should have performed well in the cold, dense air. That the pilot apparently couldn't power it out of the incipient stalls he encountered argues strongly against you or me being able to do so with our relatively underpowered flivvers.
If it requires delaying or postponing a flight, make sure the airplane is clean and free of any ice or snow before trying to take off this winter.
POLISHED FROST?
One of winter flying's oddest traditions is that of "polishing" frost--instead of removing it entirely--to eliminate the greater drag the condition creates. Natural frost on a wing's upper surface is much rougher in texture than the wing itself. Polishing it, so the theory goes, removes that roughness and, supposedly, allows a safe departure. Except there's no data supporting this theory. And, according to the FAA, "the term 'polished frost' is ambiguous since no standard of acceptable smoothness is provided." So, the agency in May 2008 proposed a rule prohibiting takeoff with polished frost. At this writing, it appears the proposal has not yet been finalized.
Reading the FAA proposal is a bit surreal. For example, the FAA notes current regulations in effect since 1960 "allow pilots to take off with frost adhering to wings or stabilizing or control surfaces if that frost has been polished to make it smooth." The agency goes on to note it and others "have accumulated an extensive amount of data that would indicate that any amount of contaminants on wings or critical surfaces could be detrimental to the flight characteristics of an aircraft." In an Advisory Circular, the FAA recommends removing all wing frost prior to takeoff but adds that any polishing should be done "according to the aircraft manufacturer's recommended procedures." Of course, no current aircraft manufacturer has any recommended procedures for polishing frost.
AIRCRAFT PROFILE: BEECH KING AIR 200
ENGINES: P&WC PT6A-42
EMPTY WEIGHT: 7538 lbs.
MAX GROSS WEIGHT: 12,500 Ibs.
TYPICAL CRUISE SPEED: 272 knots
STANDARD FUEL CAPACITY: 544 gal.
SERVICE CEILING: 32,880 ft.
RANGE: 1870 nm
Vso: 75 knotsSource Citation
Burnside, Joseph "Jeb" E. "Snow job: there's simply no excuse for not clearing all ice and snow from an airplane before trying to take off." Aviation Safety 29.12 (2009): 24+. Academic OneFile. Web. 26 Dec. 2009.
Gale Document Number:A214204550
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