• Emergency and Rescue• a) FIRE-FIGHTING SERVICE• i) equipment• ii) personnel• iii) training• b) RESCUE SERVICE• i) equipment• ii) personnel• iii) training• c) Water rescue capability, if appropriate to the

aerodrome location

• Emergency and Rescue Services• a) Fire-fighting service• i) equipment• ii) personnel• iii) training• b) Rescue service• i) equipment• ii) personnel• iii) training• c) Water rescue capability, if appropriate to the

aerodrome location.• Some of t

• Some of the recommended practices that are key to aircraft accident mitigation include:

• a) category for CFR based on largest aircraft• b) CFR response within two minutes of alarm to end

of farthest runway• c) emergency access roads maintained• d) discrete CFR communication system. This system

should involve all responding agencies including• the air traffic control tower. However, it has been

demonstrated that the ability of the CFR responders• to directly communicate with the aircraft is valuable

and should be considered if survival is a factor in• the investigation.

• Mutual Aid Resources• Aerodrome CFR resources have been expanded by the

inclusion of municipal and regional fire fighting and rescue• services. When these services are required by the nature of

the accident and available, it has been demonstrated that• post-accident response is improved. The following conditions

should be investigated to ensure mutual-aid CFR contributed to the overall effort:

• a) Agency alert and notification• b) Assembly points and routing• c) Compatibility of equipment with aircraft accident conditions

– i) Fire Fighting– ii) Communications

• d) Training of mutual-aid CFR personnel• e) Inclusion of mutual-aid in command and control

assignments

• Documentation• Investigators should retrieve and examine the

aerodrome documentation with regard to the above. Included in this documentation should be:

• a) AIP• b) NOTAMs and current ATIS• c) Aerodrome Obstruction Chart (ICAO Type A)• d) adequacy of dissemination of pertinent

information• e) aerodrome operator records, (operations logs,

NOTAMs, aerodrome inspection records, planning• documents and minutes, etc.)

• ICING

• Large turbojet transport airplanes • have not experienced any significant safety problems

during in-flight icing conditions; they have experienced a number of serious accidents during takeoff in ground icing conditions, such as snow and freezing drizzle.

• small general aviation and commuter airplanes • have experienced serious accidents resulting from ice

accumulation during in-flight operations as well as during takeoff in ground icing conditions.

• Ground deicing of aircraft is commonly performed in both commercial and general aviation. The fluid used in this operation is called de-icing or deicing fluid. The abbreviation ADF (Aircraft Deicing Fluid) is often used.

• As early as 1950, some States had established civil aviation regulations prohibiting take-off for aeroplanes with frost, snow, or ice adhering to wings, propellers or control surfaces of the aeroplane.

• The effects of such icing are wideranging, unpredictable and dependent upon individual aeroplane design. The magnitude of these effects is dependent upon many variables, but the effects can be both significant and dangerous.

• Icing can reduce wing lift by as much as 30 per cent and increase drag by up to 40 per cent

• Common practice developed by the aviation industry over many years of operational experience is to de ice/anti- ice an aeroplane prior to take-off. Various techniques for ground de-icing/anti-icing aeroplanes were also developed.

• The most common of these techniques is the use of FPD Freezing Point Depressant (FPD) fluids, fluids to aid the ground de-icing/anti-icing process and to provide a protective anti-icing film to delay the formation of frost, snow or ice on aircraft surfaces.

• Date: March 17, 1979 • Location: Moscow, Russia, USSR • Airline: Aeroflot • Aircraft: Tupolev TU-104B • Fatalities/No. Aboard: 90:90 • Details: The aircraft crashed in freezing rain and fog shortly after taking off. • Date: January 13, 1982 • Location: Washington, D.C. • Airline: Air Florida • Aircraft: Boeing 737-200 • Fatalities/No. Aboard: 74:79 + 4 • Details: The aircraft crashed into the 14th St. bridge and the Potomac River and

sank shortly after taking off from Washington National Airport. The aircraft reached a peak altitude of 300 ft. The causes were the crew's failure to use the engine anti-icing system during takeoff and failure to de-ice the plane a second time before takeoff with snow/ice on the critical surfaces of the aircraft. Ice that accumulated on the engine pressure probes resulted in erroneously high Engine Pressure Ratio (EPR) readings. When the throttles were set to takeoff EPR, the engines were actually developing significantly less than takeoff thrust. The crew's inexperience in icing conditions was a contributing factor.

• Date: February 01, 1985 • Location: Minsk, Belarus, USSR • Airline: Aeroflot • Aircraft: Tupolev TU-134A • Fatalities/No. Aboard: 58:80 • Details: The aircraft crashed during takeoff. Icing. Double engine

failure. • Date: December 12, 1985 • Location: Gander, Newfoundland, Canada • Airline: Arrow Airways • Aircraft: Douglas DC-8-63PF • Fatalities/No. Aboard: 256:256 • Details: The aircraft stalled and crashed during takeoff. There is

controversy surrounding this crash. The majority opinion of the Safety Board was that the cause of the sequence leading up to the stall and crash could not be determined, with icing a possibility.

• Deicing fluids come in a variety of types, and are typically composed of ethylene glycol (EG) or propylene glycol (PG), along with other ingredients such as thickening agents, surfactants (wetting agents), corrosion inhibitors, and colored, UV-sensitive dye. Propylene Glycol-based fluid is more common due to the fact that it is less toxic than ethylene glycol.

• The Society of Automotive Engineers publishes standards (SAE AMS 1428 & AMS 1424) for four different types of aviation deicing fluids:

• Type I fluids have a low viscosity, and are considered "unthickened". They provide only short term protection because they quickly flow off surfaces after use. They are typically sprayed on hot (130–180°F, 55-80°C) at high pressure to remove snow, ice, and frost. Usually they are dyed orange to aid in identification and application.

• Type II fluids are "pseudoplastic", which means they contain a polymeric thickening agent to prevent their immediate flow off aircraft surfaces. Typically the fluid film will remain in place until the aircraft attains 100 knots or so (almost 200 km/h), at which point the viscosity breaks down due to shear stress. The high speeds required for viscosity breakdown means that this type of fluid is useful only for larger aircraft. The use of type II fluids is diminishing in favour of type IV. Type II fluids are generally light yellow in color.

• Type III fluids can be thought of as a compromise between type I and type II fluids. They are intended for use on slower aircraft, with a rotation speed of less than 100 knots. Type III fluids are gaining acceptance in the regional and business aviation markets. Type III fluids are generally light yellow in color.

• Type IV fluids meet the same AMS standards as type II fluids, but they provide a longer holdover time. They are typically dyed green to aid in the application of a consistent layer of fluid.

• Deicing fluids containing thickeners (types II, III, and IV) are also known as anti-icing fluids, because they are used primarily to prevent icing from re-occurring after an initial deicing with a type I fluid.

• Frost • is the solid deposition of water vapor from humid

air. It is formed when the temperature of a solid surface is below the freezing point of water and also below the frost point

• Snow • is precipitation in the form of flakes of crystalline

water ice that fall from clouds• Ice• is water frozen into a solid state. It can appear

transparent or opaque bluish-white color, depending on the presence of impurities or air inclusions.

• Ice on critical surfaces and on the airframe may also break away during take-off and be ingested into engines, possibly damaging fan and compressor blades.

• Ice forming on pitot tubes and static ports or on angle of attack vanes may give false attitude, airspeed, angle of attack and engine power information for air data systems.

• It is therefore imperative that take-off not be attempted unless it has been ascertained that all critical surfaces of the aeroplane, as well as all instrument probes, are free of adhering snow, frost or

• other ice formations. • This vital requirement is known as the “Clean Aircraft

Concept”.

• Caution: • Do not use pure (100%) ethylene glycol or pure propylene

glycol fluids in non-precipitation conditions. The reasons for this caution are explained below:

• Pure ethylene glycol or pure propylene glycol have a much higher freezing point than ethylene glycol diluted with water. Slight temperature decreases can be induced by factors such as cold-soaked fuel in wing tanks, reduction of solar radiation by clouds obscuring the sun, wind effects, and lowered temperature during development of wing lift;

• Undiluted propylene glycol, having a strength of about 88% glycol at temperatures less than -10°C (+14°F), is quite viscous. In this form, propylene glycol based fluids have been found to cause lift reductions of about 20%.

• Most aeroplanes used in commercial air transport operations, as well as some other aeroplane types, are certificated for flight in icing conditions. Aeroplanes so certificated were designed to have the capability to penetrate supercooled cloud icing conditions and have demonstrated this in flight.

• This capability is provided either by ice protection equipment installed on critical surfaces, such as the leading edge, or by demonstration that the ice formed, under supercooled cloud icing conditions, on certain unprotected components will not significantly affect aeroplane performance,

• Icing Certification• Certification for flight in icing covers three principal

aspects: • Airframe and systems ice protection, • Aircraft handling and performance, • Powerplant ice protection, • Certification for flight in icing intended does not

necessarily imply fitness for or approval of continuous operations in icing conditions. In many cases, especially for smaller general aviation aircraft, it may be intended to allow for just a temporary period of operation in icing conditions during which their horizontal or vertical extent is vacated.

AIRCRAFT GROUND ICING

23

• Ground Icing• Research has concluded that fine particles of frost no

bigger than a grain of salt and distributed as sparsely as one grain

• per square centimeter can destroy enough lift to prevent the aircraft from taking off.

• Frost can accumulate on the aircraft surfaces when the surface is below the freezing temperature and there is enough moisture in the air to cause the water vapor to sublimate directly out of the air, forming small crystals of ice. Ice can form even when the Outside Air Temperature (OAT) is well above 0°C (32°F).

• An aircraft equipped with wing fuel tanks may have fuel that is at a sufficiently low temperature such that it lowers the wing skin temperature to below the freezing point. This phenomenon is known as cold-soaking.

• • This situation can also occur when an aircraft has

been cruising at high altitude for a period of time followed by a quick descent to a landing in a humid environment. Liquid water coming in

• contact with a wing, which is at a below freezing temperature, will then freeze to the wing surfaces.

• Cold-soaking • can also be caused by fueling an aircraft with cold

fuel. If there is rain or high humidity, ice can form on the cold-soaked wing and accumulate over time. This ice can be invisible to the eye and is often referred to as clear ice.

• Sheets of clear ice dislodged from the wing or fuselage during takeoff or climb can be ingested by aft fuselage mounted

• engines, thereby causing a flameout or damage. Sheets of dislodged clear ice can also cause impact damage to critical

• surfaces such as the horizontal stabilizer.• Frost may form selectively on the airplane, accumulating on

some surfaces while ignoring others. Most pilots know that if• an airplane is left on the ramp during a subfreezing night,

when there is sufficient moisture in the air, frost will appear in

• the early morning on the upper surfaces of the airplane. The upper surfaces radiate heat into the black night sky while

• the lower surfaces have radiant heat re-radiated back to the airplane from the tarmac.

• Precipitation which freezes to the upper surfaces of the airplane

• Freezing rain is super cooled water which freezes as soon as it makes contact with a surface which is at or below

• water’s freezing temperature. Although it provides a relatively smooth coating on the surface, variations in the surface

• can seriously degrade the aerodynamic performance of airfoils, decreasing its lift/thrust producing capabilities while increasing drag. Freezing rain is a hazard both on the ground and in the air. While in the air it strikes first on leading edges, and normally freezes while it flows back with the airstream.

• Consequences of frost on airplane airfoils• Although the effects of frost accumulation on the lift producing

surfaces in not as significant as the effects of the formation of ice, even small amount of frost can have a pronounced affect on their ability to produce lift and can also create drag The rough surface of frost can greatly affect the nature of the boundary layer, slowing it and increasing its thickness. Airflow separation will occur at lower than normal angles of attack and coefficients of lift will be reduced at high angles of attack. The formation of a hard layer of thick frost on the leading edges and upper surfaces of a wing have been reported to reduce maximum coefficient of lift by as much as 50%.

• Stall induced by frost will also occur at lower than normal angles of attack. Thus not only will stall speeds increase, the accuracy of stall warning devices, which depend on either airspeed or angle of attack, will be degraded.

• Effects of freezing rain or snow on airplane airfoils• Freezing rain or frozen snow on the upper surface of

a wing can cause an even greater effect (than frost) on the lift and drag producing abilities of a wing. In addition, the ice can add a significant amount of weight to the aircraft, weight that was not accounted for when computing the takeoff roll, takeoff speed, and initial climb speed. Ice can also freeze in the

• gaps and recesses of the primary and/or secondary flight controls, restricting their movement. Furthermore ice can freeze over unheated pitot static ports, denying information to the aircrew and systems which need them.

• The clean aircraft concept• During conditions conducive to aeroplane icing during

ground operations, take-off shall not be attempted when ice, snow,

• slush or frost is present or adhering to the wings, propellers, control surfaces, engine inlets or other critical surfaces

• A large number of variables can influence the formation of ice and frost and the accumulation of snow and slush causing

• surface roughness on an aeroplane. These variables include:• a) ambient temperature;• b) aeroplane skin temperature;• c) precipitation rate and moisture content;• d) de-icing/anti-icing fluid temperature;

• e) the fluid/water ratio of the de-icing/anti-icing fluid;• f) relative humidity; and• g) wind velocity and direction.• Relative humidity is the ratio of the partial pressure of

water vapor in an air-water mixture to the saturated vapor pressure of water at a prescribed temperature. The relative humidity of air depends not only on temperature but also on the pressure of the system of interest. Relative humidity is normally expressed as a percentage and is calculated by using the following equation:[

• 1

Elevator controlMaintenance and ground crews should establish an inspection and cleaning schedule for deicing/anti-icing fluid residue to help ensure that no flight control

restrictions will occur

The damaged stator disk drive lugs on this carbon heat-sink demonstrate the type of damage alkali metal-based runway deicers can cause to carbon brake

disks

DE-ICING AND ANTI-ICING METHODS

• De-icing/anti-icing is generally carried out by using heated fluids dispensed from spray nozzles mounted on specially designed de-icing/anti-icing trucks.

• Other methods include de-icing/anti-icing gantry spraying systems, small portable spraying equipment, mechanical means (brushes, ropes, etc.), infra-red radiation, and forced air.(OSLO, Norway — Europe's first aircraft deicing hangar using infrared heat rather than polluting chemicals opened at Oslo Airport-Gardermoen on Wednesday, January 19, 2006)

• De-icing/anti-icing fluids are applied close to the skin of the aeroplane to minimize heat loss. Unique procedures to accommodate aeroplane design differences may be required.

De-Icing and anti-icing methods

• A primitive method of ground removal of snow and ice is to sweep• Another method of preventing the accumulation of frost, freezing rain

or snow on an aircraft is to keep the aircraft protected from the elements until just prior to its use.(Hanger)

• The most common method of removing ice or snow from large commercial aircraft is the use of a de-icing and/or an antiicing fluid. De-icing fluid is used to remove accumulated snow and ice from the surface of an aircraft

• De-icing/anti-icing is generally carried out by using heated fluids dispensed from spray nozzles mounted on specially

• designed de-icing/anti-icing trucks. Other methods include de-icing/anti-icing gantry spraying systems, small portable spraying equipment, mechanical means (brushes, ropes, etc.), infra-red radiation, and forced air.

Truck Platform

Fixed GantryFixed Gantry Platform

• Overspray: Lack of sensors and automation cause over spray

• Under spray: Large distances from deicing nozzles to aircraft surface, bad weather cause flight critical areas to be improperly deiced

• Fugitive Glycol:The large distances from nozzles to aircraft surfaces combined with bad weather create large clouds of fugitive glycol. These clouds harm the environment and do nothing to deice the aircraft

38

Deicing and Anti-icing Today…

Today’s methods will not meet Tomorrow’s standards

A picture is worth a thousand words…

Permanent System – ATS 2000

RNR Engineering Innovations

44

Truck Mounted Mobile System - DAMS

RNR Engineering Innovations

45

• Produces temperature map of flight critical surfaces

• (Insures safe deicing by pointing out “cold spots” of aircraft that need special attention)

• Produces temperature map of applied layer of anti-icing fluid

• (Pinpoints potential weak spots in anti-icing layer)

• (Insures efficient anti-icing fluid application by showing flight critical surfaces not yet anti-iced)

Infrared Temperature Mapping

Investigating accidents in which ground icing is a suspected factor

• Inspections used to determine the need for de-icing and anti-icing

• Some of the factors to be examined in this are include:• a) Existence of formal procedures.• b) Adequacy of procedures to detect icing in critical areas.• c) Visibility of critical areas to include the effects of

adequacy of lighting, viewing angles and reduced• visibility from inside the cabin due wet and/or scratched

windows.• d) Training of ground and flight crew performing the

inspections.

• Procedures used to de-ice and anti-ice the aircraft• Some of the factors to be examined in this area include:• a) The existence of formal procedures for de-icing and anti-icing

the aircraft.• b) Compliance with procedures for de-icing and anti-icing the

aircraft including the sequence followed to• de-ice and anti-ice the various surfaces, avoidance of surface

areas which should not be exposed to• anti-icing fluids, training of ground crews in de-icing and anti-icing

procedures and communication of• critical information concerning de-icing or anti-icing to the flight

crew.

• The type of fluid and concentrations in the solution used to de-ice and anti-ice the aircraft

• Some of the factors to be examined in this area include:

• a) Procedures to ensure the quality of the fluids being used.

• b) Procedures to ensure the accuracy of the mixtures used in the solutions applied to the aircraft.

• In-flight Icing• In flight icing can be divided into two types:

structural and engine ice. Structural ice degrades the airplane performance

• when super cooled water droplets impinge on aircraft surfaces. Ice build-ups can then degrade lift production, increase drag, reduce propeller efficiency, increase airplane weight and, if shed by the structure on which it forms, cause damage

• to systems or structure. Engine ice can degrade thrust or power production by the power plant by starving it of air.

Aircraft Anti-Icing Systems

Negative Effects of Ice Buildup• Destroys smooth flow of air over

wing, leading to severe decrease in lift and increase in drag forces

• Can change pitching moment• As angle of attack is increased to

compensate for decreased lift, more accumulation can occur on lower wing surface

• Causes damage to external equipment such as antennae and can clog inlets, and cause impact damage to fuselage and engines

• Considered a cumulative hazard because as ice builds up on the wing, it increasingly changes the flight characteristics

•http://www.aopa.org/asf/publications/sa11.pdf#search=%22anti-icing%20systems%20aircraft%22

Types of Ice• Rime: “has a rough milky white

appearance and generally follows the surface closely”

• Clear/Glaze: “sometimes clear and smooth but usually contain some air pockets that result in a lumpy translucent appearance, denser, harder and more difficult to break than rime ice”

• Mixed

http://virtualskies.arc.nasa.gov/weather/tutorial/images/32clearice.gif&imgrefurl=http://virtualskies.arc.nasa.gov/weather/tutorial/tutorial4.html&h=235&w=280&sz=29&hl=en&start=6&tbnid=NrYdps_943cEmM:&tbnh=96&tbnw=114

Types of Ice Removal• Anti-Icing

– Preemptive, turned on before the flight enters icing conditions

– Includes: thermal heat, prop heat, pitot heat, fuel vent heat, windshield heat, and fluid surface de-icers

• De-Icing– Reactive, used after there has been significant ice

build up– Includes surface de-ice equipment such as boots,

weeping wing systems, and heated wings

Propeller Anti-Icers

• Ice usually appears on propeller before it forms on the wing

• Can be treated with chemicals from slinger rings on the prop hub

• Graphite electric resistance heaters on leading edges of blades can also be used

•http://www.aopa.org/asf/publications/sa11.pdf#search=%22anti-icing%20systems%20aircraft%22

Windshield Anti-Icers

• Liquids used include: ethylene glycol, propylene glycol, Grade B Isopropyl alcohol, urea, sodium acetate, potassium acetate, sodium formate, and chloride salts

• Chemicals are often bad for the environment

• Usually uses resistance heat to clear windshield or chemical sprays while on the ground

•http://www.aopa.org/asf/publications/sa11.pdf#search=%22anti-icing%20systems%20aircraft%22

Thermal Heat• Air Heated

– Bleed air from engine heats inlet cowls to keep ice from forming

– Bleed air can be ducted to wings to heat wing surface as well

– Ice can also build up within engine, so shutoff valves need to be incorporated in design

– Usually used to protect leading edge slat, and engine inlet cowls

• Resistance heater– Used to prevent ice from forming on

pitot tubes, stall vanes, temperature probes, and drain masts

Airplane Design, Book 4, Roskam

Boots• Inflatable rubber strips that run

along the leading edge of wing and tail surfaces

• When inflated, they expand knocking ice off of wing surface

• After ice has been removed, suction is applied to boots, returning them to the original shape for normal flight

• Usually used on smaller planes

•http://www.aopa.org/asf/publications/sa11.pdf#search=%22anti-icing%20systems%20aircraft%22

Weeping Wing• Fluid is pumped through

mesh screen on leading edge of wing and tail

• Chemical is distributed over wing surface, melting ice

• Can also be used on propeller blades and windshields

•http://www.aopa.org/asf/publications/sa11.pdf#search=%22anti-icing%20systems%20aircraft%22

Electro-impulse Deicing

• Electromagnetic coil under the skin induces strong eddy currents on surface

• Delivers mechanical impulses to the surface on which ice has formed

• Strong opposing forces formed between coil and skin

• Resulting acceleration sheds ice from the surface

• Can shed ice as thin as 0.05”

•http://www.idiny.com/eidi.html

• EIDI - Electro Impulse Deicing• Electro Impulse Deicing is an acceleration based deicer for use on large

aircraft, ship and bridge surfaces for general ice protection. The system was developed in collaboration with a NASA Glenn SBIR program. An electromagnetic coil is placed behind the surface skin that induces strong eddy currents in the metal surface. As a result, strong opposing forces are developed between the actuator coil and the metal skin. This results in a rapid acceleration that sheds and de-bonds ice into the air stream in a very efficient manner (ice layers can be shed as thin as .050"). EIDI represents a technically advanced low power deicing system alternative to electrothemal and bleed air anti-icing systems. IDI's Icing Onset Sensorcan be added to the basic system to provide an autonomous mode of operation. The IOS detects the initiation of ice accretion (icing onset) and continuously monitors the amount of accumulation. When the accumulation reaches a thickness threshold at which efficient clearing is possible, the sensor commands the deicer to fire. Because the sensor continuously monitors the accumulation, the sensor can determine if the ice was properly shed or if another clearing cycle is required. The sensor continues to monitor accretion and initiate deicing cycles as required.

Typical Anti-Icing• C-130:

– Engine bleed air used for anti-icing wing and empennage leading edges, radome, and engine inlet air ducts.

– Electrical heat provides anti-icing for propellers, windshield, and pitot tubes.

• 777: – Engine bleed air used to heat engine cowl inlets. If leak is

detected in Anti-Ice duct, affected engine Anti-Ice valves close.

– Wing Anti-Ice System provides bleed air to three leading edge slats on each wing. Wing Anti-Ice is only available in flight.

RADOME

• Investigating accidents in which in-flight icing is a suspected factor.

• When investigating accidents involving aircraft icing, the investigator needs to examine not only what happened, but why it happened. These are some of the questions that may need to be answered:

• a) Why did the pilot fly into icing conditions which the aircraft was not able to safely penetrate?

• b) Did the pilot seek a pre-flight weather briefing?• c) If a briefing was provided, was it accurate?• d) Did the pilot seek or did air traffic control provide

updates of significant weather?• e) Did the pilot know that ice was accumulating on the

critical aircraft surfaces?

• Another series of questions addressed aircraft systems and their ability to detect, prevent the accumulation or eliminate

• the accumulation of ice:• a) Were anti-ice and de-ice system functional and effective?• b) Did the crew know how and when to operated anti-ice and

de-ice systems such as airfoil leading edge boots, electrically and engine bleed air heated surfaces, and glycol systems?

• c) Were the anti-icing or de-icing systems installed on the aircraft capable of functioning in the icing environment encountered by the aircraft?

• d) Was the aircraft flown at a higher or lower than normal angles-of –attack, allowing ice to accumulate on unprotected airfoil surfaces which were aft of leading edge de-icing devices?