AVIATION Reports - 2005 - A05C0187

Appendices

1. Appendix A - Centre of Gravity Calculations
2. Appendix B - Graphic Area Forecasts for the Route of Flight
3. Appendix C - Icing Parameters
4. Appendix D - Altitude versus Rate of Climb/Descent
5. Appendix E - Altitude versus Groundspeed/Airspeed
6. Appendix F - Other Occurrences
7. Appendix G - List of Supporting Reports
8. Appendix H - Glossary

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Appendix A - Centre of Gravity Calculations

			Most Forward Centre of Gravity		Most Aft Centre of Gravity
Item	Zone	Maximum Weight*	Item Weight*	Item Index	Item Weight*	Item Index
Cabin Cargo	1	415	415	983	264	990
	2	860	860	44	860	44
	3	495	495	71	495	71
	4	340	340	70	340	70
	5	315	164	41	315	80
	6	245
Pod Cargo	A	230
	B	310	120	998	120	998
	C	270	80	6	80	6
	D	280
Pilot Weight			120	985	120	985
Aircraft Basic Weight			4837	438	4837	438
Take-off Fuel			1607	40	1607	40
Gross Take-off Weight			9038	3676	9038	3722
Centre of Gravity			36.2% MAC**		40.1% MAC**

* All weights are given in pounds.
** MAC - mean aerodynamic chord

Appendix B - Graphic Area Forecasts for the Route of Flight

Icing and Turbulence, Winnipeg area (valid October 6 at 0600 UTC)

Appendix C - Icing Parameters

Appendix C to Part 25 of the Federal Aviation Regulations (FAR 25) (United States)

(a) Continuous maximum icing. The maximum continuous intensity of atmospheric icing conditions (continuous maximum icing) is defined by the variables of the cloud liquid water content, the mean effective diameter of the cloud droplets, the ambient air temperature, and the inter-relationship of these three variables as shown in figure 1 of this appendix. The limiting icing envelope in terms of altitude and temperature is given in figure 2 of this appendix. The inter-relationship of cloud liquid water content with drop diameter and altitude is determined from figures 1 and 2. The cloud liquid water content for continuous maximum icing conditions of a horizontal extent, other than 17.4 nautical miles, is determined by the value of liquid water content of figure 1, multiplied by the appropriate factor from figure 3 of this appendix.

(b) Intermittent maximum icing. The intermittent maximum intensity of atmospheric icing conditions (intermittent maximum icing) is defined by the variables of the cloud liquid water content, the mean effective diameter of the cloud droplets, the ambient air temperature, and the inter-relationship of these three variables as shown in figure 4 of this appendix. The limiting icing envelope in terms of altitude and temperature is given in figure 5 of this appendix. The inter-relationship of cloud liquid water content with drop diameter and altitude is determined from figures 4 and 5. The cloud liquid water content for intermittent maximum icing conditions of a horizontal extent, other than 2.6 nautical miles, is determined by the value of cloud liquid water content of figure 4 multiplied by the appropriate factor in figure 6 of this appendix.

The charts referred to in paragraphs (a) and (b) above are available at www.airweb.faa.gov.

Appendix D - Altitude versus Rate of Climb/Descent

Appendix E - Altitude versus Groundspeed/Airspeed

Appendix F - Other Occurrences

On 27 February 1990, at Denver, Colorado, United States, a Cessna 208A was destroyed with one fatality. The National Transportation Safety Board (NTSB) factual report (DEN90FA068) indicates that moderate-to-heavy icing conditions were forecast for the Denver area, freezing drizzle was observed, and the aircraft encountered icing conditions on final approach. The NTSB determined the probable cause of the accident to be "the accumulation of structural ice and subsequent stalling of the aircraft."

On 30 November 1995, at Ardmore, Oklahoma, United States, a Cessna 208B sustained substantial damage and the pilot sustained minor injuries. The NTSB factual report (FTW95FA129) indicates that freezing drizzle was reported at the airport. The aircraft rapidly accumulated ice during the approach, resulting in an inability to maintain altitude and a controlled impact with terrain during an off-airport forced landing. The NTSB determined that "icing conditions prevailing at the destination airport" were a factor in the accident.

On 04 March 1997, at Barrie, Ontario, a Cessna 208B was destroyed with one fatality. The TSB investigation report (A97O0032) indicates that moderate rime icing and moderate mixed icing in light freezing drizzle were forecast, and freezing drizzle was reported in the vicinity of the airport. The TSB made a finding that "ice accumulation on the unprotected leading edge surfaces of the aircraft degraded aircraft performance . . .," and that "the aircraft struck the ground for undetermined reasons."

On 25 November 1997, at North Bay, Ontario, a Cessna 208B sustained substantial damage and two people sustained serious injuries. The TSB investigation report (A97O0247) indicates that light-to-moderate rime icing in cloud and moderate-to-severe mixed icing in freezing drizzle were forecast. The aircraft stalled on final approach. The TSB found that "ice accumulation on the unprotected leading edge surfaces and underside wing surfaces degraded aircraft performance, increasing the stall speed."

On 20 January 1998, at Grand Island, Nebraska, United States, a Cessna 208B sustained substantial damage and the pilot was not injured. The NTSB factual report (CHI98LA084) indicates that the aircraft encountered icing conditions en route. When the pilot reduced power for landing, the aircraft stalled and landed hard. The NTSB determined the probable cause of the accident to be "ice build-up on the airplane's wings and empennage which led to an inadvertent stall and hard landing."

On 05 March 1998, at Clarksville, Tennessee, United States, a Cessna 208B was destroyed with one fatality. The NTSB factual report (MIA98FA091) indicates that light occasional moderate rime icing in cloud was forecast. The aircraft encountered icing conditions, resulting in degraded performance, loss of control, and impact with the terrain. The NTSB determined the probable cause of the accident to be that "the pilot did not maintain control of the airplane due to undetected airframe ice, resulting in an inadvertent stall, and subsequent impact with the ground."

On 07 March 1998, at Bismarck, North Dakota, United States, a Cessna 208B was destroyed with one fatality. The NTSB factual report (CHI98FA119) indicates that the aircraft encountered icing conditions en route, and that a loss of control occurred during final approach, resulting in impact with terrain. The NTSB determined that "factors associated with the accident were the icing conditions."

On 28 April 2001, at Roque Perez, Argentina, a Cessna 208B was destroyed with 10 fatalities. The NTSB preliminary report (MIA01WA133), based on information from the Argentine investigation authority, indicates that conditions aloft were favourable for the formation of airframe icing, and that the pilot requested permission to descend to a lower altitude due to ice formation on the wings.

On 05 May 2001, at Steamboat Springs, Colorado, United States, a Cessna 208B was destroyed with one fatality. The NTSB factual report (DEN01FA094) indicates that occasional moderate rime and mixed icing in clouds were forecast. The aircraft stalled on final approach, resulting in impact with terrain. The NTSB determined the probable cause of the accident to be "an inadvertent stall during an instrument approach, which resulted in a loss of control. Contributing factors were . . . conditions conducive to airframe icing."

On 06 March 2002, at Barrow, Alaska, United States, a Cessna 208B sustained substantial damage and the pilot and four passengers were not injured. The NTSB factual report (ANC02FA020) indicates that severe icing was forecast and that the aircraft stalled on approach. The NTSB determined the probable cause of the accident to be "the pilot's continued flight into adverse weather conditions, and an inadvertent stall. Factors associated with the accident are . . . icing conditions."

On 15 March 2002, at Alma, Wisconsin, United States, a Cessna 208B was destroyed with one fatality. The NTSB factual report (CHI02FA093) indicates that severe mixed and clear icing conditions in clouds and in precipitation were forecast. The pilot encountered icing inbound to an en route stop. The pilot did not have the aircraft de-iced, choosing instead to chip the ice off the aircraft before departure. "The pilot departed with the airplane contaminated with ice, into known severe icing conditions, and was unable to maintain altitude, subsequently impacting trees and terrain." The NTSB determined that one of the factors associated with the accident included the icing conditions.

On 08 November 2002, at Parks, Arizona, United States, a Cessna 208B was destroyed with four fatalities. The NTSB factual report (DEN03FA012) indicates that moderate mixed and rime icing was forecast. The flight encountered icing en route at 15 000 feet and a loss of control and impact with terrain occurred.

On 24 January 2003, at San Angelo, Texas, United States, a Cessna 208B was destroyed with two serious injuries. The NTSB preliminary report (FTW03FA089) indicates that witnesses "observed between 1/4 and 1-inch of ice on the various protected and unprotected surfaces of the aircraft." This investigation is ongoing and no final report is available.

On 29 October 2003, at Cody, Wyoming, United States, a Cessna 208B was destroyed with one fatality. The NTSB factual report (DEN04MA015) indicates that the pilot reported light rime icing at 12 000 feet. A loss of control and impact with terrain occurred. The NTSB determined that an inadvertent stall and the snow and icing conditions were contributing factors.

On 04 November 2003, at Bangor, Maine, United States, a Cessna 208B sustained minor damage and the pilot was not injured. The NTSB factual report (NYC04IA023) indicates that occasional moderate rime and mixed icing in precipitation and clouds were forecast. The flight encountered freezing rain en route, and the pilot requested descent and diversion to Bangor. The pilot "had no forward visibility through the windshield" and the aircraft landed hard on the runway without any landing flare. The NTSB determined that the probable cause of the incident was "the pilot's inability to see through the windshield, which was obscured due to icing conditions. . . . A factor contributing to the accident was the wing icing."

On 06 December 2004, at Bellevue, Idaho, United States, a Cessna 208B was destroyed with two fatalities. The NTSB factual report (SEA05FA025) indicates that occasional moderate rime or mixed icing in clouds and precipitation was forecast, and that an aircraft on approach ahead of the Cessna 208B encountered light-to-moderate rime ice. The NTSB determined that the probable cause of the accident was "the pilot's failure to maintain aircraft control while on approach for landing in icing conditions."

On 19 November 2005, at Moscow, Russia, a Cessna 208B was destroyed with eight fatalities. The Russian investigation is ongoing. Information from the Russian investigative authorities, based on data from the on-board flight data recorder, indicates that the aircraft was in level flight into icing conditions and experienced a reduction in airspeed. The crew lost control of the aircraft at about 102 knots, and an impact with terrain occurred.

On 22 November 2005, near Yellowknife, Northwest Territories, a Cessna 208B was not damaged and the pilot and five passengers were not injured. The TSB occurrence (A05C0217) narrative indicates that the flight encountered icing conditions and degraded performance while diverting en route and climbing to 9000 feet. A loss of control occurred at an airspeed just above 100 knots. The pilot regained control with a loss of about 1500 feet, and the flight returned to Yellowknife. The graphic area forecast indicated light icing; however, moderate mixed icing conditions were forecast in freezing drizzle.

On 22 March 2006, near London, Ontario, a Cessna 208B encountered icing conditions at an altitude of 4000 feet and climbed to 6000 feet, but was unable to avoid the icing conditions (TSB occurrence A06O0076). The de-icing system was activated but was unable to keep up with the rate of ice formation on the wings. Aircraft performance was deteriorating and, at full engine power, the aircraft was unable to climb at 120 knots, at a gross weight of about 7150 pounds. The autopilot was off and the crew noted that the controls had become sluggish. The aircraft diverted to nearby London and the flight crew performed shallow turns when heading changes were required. The aircraft landed safely at the London Airport and continued to destination after the icing conditions had cleared the area. The flight crew had checked the en route weather conditions approximately one hour before take-off and there were no reports of icing conditions for their flight. Several pilot reports (PIREPs) were received from other aircraft (both were de Havilland DHC-8), which also encountered icing conditions in the area. No reports of control difficulties were received from these aircraft.

Appendix G - List of Supporting Reports

The following TSB Engineering Laboratory reports were completed:

• LP 110/05 - FDR/Aircraft Performance Analysis
• LP 111/05 - Engine Instrument Examination
• LP 121/05 - De-Ice Valve Analysis

These reports are available upon request from the Transportation Safety Board of Canada.

Appendix H - Glossary

AD	Airworthiness Directive
AFM	aircraft flight manual
agl	above ground level
asl	above sea level
ATC	air traffic control
ATIS	automatic terminal information service
ATPL	airline transport pilot licence
CG	centre of gravity
CIP	Current Icing Potential
CN	Canadian National
CVR	cockpit voice recorder
FAA	Federal Aviation Administration
FARs	Federal Aviation Regulations
FBO	fixed-base operator
FDR	flight data recorder
FIC	Flight Information Centre
FIP	Forecast Icing Potential
fpm	feet per minute
GFA	graphic area forecast
IFR	instrument flight rules
IMC	instrument meteorological conditions
in Hg	inches of mercury
ITT	inter-turbine temperature
KIAS	knots indicated airspeed
MAC	mean aerodynamic chord
MANAIR	Manual of Standards and Procedures for Aviation Weather Forecasts (Environment Canada publication)
METAR	aviation routine weather report
Morningstar	Morningstar Air Express Inc.
Ng	gas generator speed
NOAA	National Oceanic & Atmospheric Administration
NTSB	National Transportation Safety Board
PAR	power analyzer recorder
PIREP	pilot report
POH	Pilot's Operating Handbook
PPC	pilot proficiency check
SIGMET	significant meteorological message
sm	statute miles
SPECI	special weather observation
TAF	aerodrome forecast
TC	Transport Canada
TSB	Transportation Safety Board of Canada
UTC	Coordinated Universal Time
VMC	visual meteorological conditions
Vy	best rate of climb airspeed
º	degrees
ºC	degrees Celsius
%	per cent

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1. All times are central daylight time (Coordinated Universal Time [UTC] minus five hours)

2. See Glossary at Appendix H for all abbreviations and acronyms.

3. The investigation determined that company Caravan pilots based in Winnipeg did not normally leave a copy of the weight and balance form at the point of departure.

4. Index values simplify the calculation of centre of gravity.

5. The cloud droplet size is important in determining icing severity, because the higher the liquid water content of a cloud and the larger the size of its droplets, the more likely these droplets are to collide with and, therefore, freeze to the hard surface of a plane. Small cloud droplets-less than 30 microns (30 millionths of a metre) in diameter-are less likely to collide with an aircraft surface because they are lighter and tend to follow the air flow around the plane. Larger drops, such as freezing drizzle (100 to 500 microns) or freezing rain (500 to 3000 microns), are more likely to collide because of their greater momentum. Reference: Environment Canada, "Icing Research Making Skies Safer," in Science and the Environment Bulletin, Issue 16, January/February 2000.

6. The flight scenarios were performed early in the investigation before the more accurate estimate of aircraft take-off weight (9038 pounds) was determined. Therefore, the flight scenarios flown with a weight of 8809 pounds were conservative.

7. See Appendix C - Icing Parameters

8. In the Transport Canada publication TP 10643 titled When in Doubt . . . Small and Large Aircraft - Aircraft Critical Surface Contamination Training for Aircrew and Groundcrew, "critical surface" is defined as ". . . the wings, control surfaces, rotors, propellers, horizontal stabilizers, vertical stabilizers or any other stabilizing surface on an aircraft. . ." The Cessna 208 Pilot's Operating Handbook Supplement S1, Revision 7, specifies the surfaces to be inspected for that aircraft type.