DOES STRUCTURAL ICE CONCERN YOU?

SAFETY THROUGH PROFESSIONALISM

DOES STRUCTURAL ICE DOES STRUCTURAL ICE CONCERN YOU? CONCERN YOU?

IT SHOULD!


WE WILL DISCUSSWE WILL DISCUSS

NASTY STATISTICS The Reg’s applicable to ICG Recognizing hazardous conditions Avoiding hazardous conditions Escaping without losing control References for more details


NASTY Facts about ICING NASTY Facts about ICING AccidentsAccidents

11% of weather accidents involve ICING 57% of ICING accidents involved SINGLE

ENGINE FIXED GEAR AIRCRAFT 49% of Pilots involved had >1000 PIC 25% of Pilots had >100 <500 PIC


MORE NASTY Facts…MORE NASTY Facts… 53% of icing accidents occurred in

MOUNTAINOUS AREAS 14% occurred near large bodies of

WATER 57% of Pilots received WX Briefings and

ICING CONDITIONS were indicated 49% OF ICING ACCIDENTS resulted in

FATALITIES


AT HIGHEST RISK-AT HIGHEST RISK-

EXPERIENCED PILOTS Who received WX BRIEFINGSFlying SINGLE ENGINE FIXED GEAR

AIRCRAFTNear MOUNTAINS or LARGE

BODIES of WATER


REGULATIONREGULATIONMISCONCEPTIONSMISCONCEPTIONS

FAR 91- DOES NOT SPECIFICALLY ADDRESS ICING for small aircraft

91.517 is in Subpart F and applies only to large and turbojet powered aircraft

BEWARE- NTSB Case law


WHAT IS “KNOWN” ICE?WHAT IS “KNOWN” ICE?

NTSB Case Law DEFINITION: Icing conditions are considered to exist if these conditions are forecast or reported.


““KNOWN” ICE FORECASTSKNOWN” ICE FORECASTS

AIRMET ZULU FOR ICE– AIRMET ICE...MA CT RI NY PA NJ WV MD DE DC

VA AND CSTL WTRS FROM ALB TO 140ENE ACK TO 200SE ACK TO SBY TO 50WSW BKW TO HNN TO AIR TO ERI TO ALB OCNL MOD RIME/MXD ICGICIP BTN 100 AND FL210. CONDS ENDG 19-21Z N OF AIR TO CYN TO 160ESE ACK LN. CONDS CONTG BYD 21Z THRU 03Z ELSW.

– FRZLVL...020-050 NRN HLF ME. 060-100 RMNDR N OF 40W ROD-EWC-CYN-160ESE ACK LN. 100-130 S OF 40W ROD-EWC-CYN-160ESE ACK LN.


““KNOWN” ICE REPORTSKNOWN” ICE REPORTS

PIREPS-– AUW UA /OV 22 NE AUW /TM 2028 /FL

070 /TP C208 /SK BL /TA -2C /IC LGT CLR /RM B/L LVN

– UA /OV FGT/TM 1917/FLUNKN/TP B737/TA 01 @ 100/M07 @ 180/IC LGT RIME 100-180/RM DURGC


REGULATION REGULATION MISCONCEPTIONSMISCONCEPTIONS

COMBINE “KNOWN ICE” WITH: 91.9 Manuals, placards, and markings

– Placards or POH/AFM MAY state “Flight in known ice is prohibited”

91.13 Careless & Reckless Operation– MAY apply if you get into icing trouble in an

unequipped airplane


REGULATION REGULATION MISCONCEPTIONSMISCONCEPTIONS

Parts 121 AND 135 DO address icing extensively– EXCELLENT GUIDANCE BUT “OPTIONAL”

FOR G.A. OPERATION


REMEMBERREMEMBER

Aviate, Navigate, Communicate, Litigate

ATC wants you on the ground safe Chance of paperwork or FAA Sanction is

remote


STILL...STILL...

SOME PILOTS will CONTINUE to attempt to fly unprotected aircraft IFR when icing is forecast

SOME PILOTS (IFR & VFR) will continue to have inadvertent icing encounters

SOME PILOTS will DIE in icing


WE WILL EXPLORE-WE WILL EXPLORE-

ENVIRONMENTAL FACTORS PROMOTING ICE

STRUCTURAL ICING CHARACTERISTICS ESCAPE AND AVOIDANCE TECHNIQUES HANDLING ICING EMERGENCIES


ENVIRONMENTALENVIRONMENTAL

WEATHER DROPLET SIZE COLLECTION EFFICIENCY


WEATHER BASICSWEATHER BASICS

ICE REQUIRES:– VISIBLE MOISTURE– TEMPERATURES BELOW FREEZING

VISIBLE MOISTURE CAN BE:– CLOUDS OR– PRECIPITATION



WARMER AIR holds more moisture than COLDER AIR

AIR is cooled by UPLIFTING (ADIABATIC COOLING)

UPLIFTING CAN BE LOCALIZED OR WIDESPREAD



LIQUID WATER CAN EXIST AT TEMPERATURES BELOW FREEZING (SUPER-COOLING)

+2 TO –15 dg C = HIGH PROBABILITY OF ICING

CLOUDS COLDER THAN –15 dg C ARE FREEZING (Cloud Glaciation)


DROPLETS GROW WITH:DROPLETS GROW WITH:

INCREASED LIQUID WATER CONTENT (LWC)

FURTHER COOLING (CONDENSATION) MORE TIME TO COALESCE ATMOSPHERIC MOVEMENT TO PROMOTE

COALESCENCE


ICING TYPES Smallest to ICING TYPES Smallest to Largest Droplets:Largest Droplets:

RIME ICE (Small Droplets) “SNAP” CLEAR ICE (Larger droplets) “SPLAT”


TYPES TYPES OFOFICEICE


ICING TYPES Smallest to ICING TYPES Smallest to Largest Droplets:Largest Droplets:

MIXED ICE (Rime/Clear/Rime/Clear) SLD ICE (Supercooled Large Droplets

range from just smaller than mist to FREEZING DRIZZLE / RAIN)

FREEZING PRECIPITATION


RISK INCREASES WITH RISK INCREASES WITH DROPLET SIZEDROPLET SIZE

LARGER DROPLETS IN:– CLOUD TOPS – OLD CLOUDS– BUMPY AIR– “WARM” (-5 TO +2 C) – CUMULUS (LIFTING)

SMALLER DROPLETS IN:– CLOUD BASES– YOUNG CLOUDS– SMOOTH AIR– “COLD” (<10 C)– STRATUS (FLAT)


WHERE WILL WE FIND WHERE WILL WE FIND MORE SEVERE ICING?MORE SEVERE ICING?

– TOWERING Cu (above freezing level) – THUNDERSTORMS– JUST BELOW INVERSIONS**– LAKE EFFECT CUMULUS– STRONG OROGRAPHIC UPLIFTING


WHERE ARE THE WORST WHERE ARE THE WORST ICING CONDITIONS?ICING CONDITIONS?

FREEZING DRIZZLE AND RAIN– ASSOCIATED WITH WARM / OCCLUDED

FRONTS – PRECIP FALLS AS LIQUID THROUGH

WARMER AIR INTO FREEZING AIR BELOW INVERSION


SLD PROBABILITYSLD PROBABILITY


COLLECTION EFFICIENCYCOLLECTION EFFICIENCY

SMALLER RADIUS FEATURES GATHER ICE FASTER– Sharp vs. rounded leading edges – Ice itself– Horizontal / Vertical Stabilizers– Tips vs. roots– Struts– Propeller blades – Antennas– OAT Probes and Windshield Wipers


PROPELLER BLADE ICEPROPELLER BLADE ICE

SHARP LEADING EDGE- MORE ICE


WING VS. TAIL,WING VS. TAIL,ROOT VS. TIP,ROOT VS. TIP,

CESSNA VS. MOONEYCESSNA VS. MOONEY


RECOGNIZING POTENTIAL RECOGNIZING POTENTIAL ICING CONDITIONSICING CONDITIONS

ACTUAL ICING AREAS TYPICALLY LOCALIZED– ALTITUDE +/- 3000 FEET– WIDTH VARIABLE, OFTEN LESS THAN 50

MILES– Synoptic Weather (moisture & lifting)– Surface features (lakes & mountains)


WEATHER BRIEFING:WEATHER BRIEFING:

– Advisories (Airmet And Sigmet Warnings)– SYNOPSIS and AREA FORECASTS – SURFACE and 500 MB CHARTS– Winds and Temperatures Aloft– Pilot Reports– A.D.D.S. Neural Network Icing Forecasts


PRE-FLIGHT PLANNINGPRE-FLIGHT PLANNING

ROUTE & ALTITUDE VS: – Weather Briefing– Terrain – Obstruction Clearance– LARGE Bodies of “Warm” Water– Suitable Alternates– Payload And Fuel Vs. Performance


PRE-FLIGHT PLANNINGPRE-FLIGHT PLANNING

DEVELOP ESCAPE ROUTES SELECT ALTERNATE AIRPORTS

– Approaches– Runway lengths– Surrounding Terrain

RESOLVE FUEL QUANDARY– More is required when running high power– Less is desired to keep weight down


ENROUTE VIGILANCE ENROUTE VIGILANCE

Watch & listen for:– Temperature Changes– Cloud Heights And Characteristics– Surface Weather Changes– Center Weather Advisories– New Pilot Reports– STRANGE NEW NOISES, HUMS, MOANS, ETC.


CHARACTERIZING ICING CHARACTERIZING ICING ACCUMULATIONACCUMULATION

TRACE- – Barely forming, not hazardous

LIGHT ICING- – Less than 1 inch accumulation per hour– Ice protection systems keep up easily– Unprotected aircraft can escape but must do

so within 20 – 30 minutes



MODERATE ICING- 1 – 3 inches per hour, – NEED ice protection systems– DANGEROUS for unprotected aircraft



SEVERE ICING-– rapid buildup, – more than 3 inches per hour, (CAN EXCEED 24

INCHES PER HOUR)– ice protection systems cannot keep up, – ice forming on unprotected areas causing

significant drag, – Runback causes feathers and ridges spoil lift


EFFECT OF ICING ON EFFECT OF ICING ON PERFORMANCEPERFORMANCE

ICE MODIFIES AERODYNAMICS– INCREASES PARASITE DRAG– SERIOUSLY MODIFIES AIRFOIL – LEADS TO:

• HIGHER ANGLES OF ATTACK• INCREASED STALL SPEED • AWKWARD CONTROL CHARACTERISTICS


EFFECT OF ICING ON EFFECT OF ICING ON PERFORMANCEPERFORMANCE

ICE ACCUMULATION RESULTS IN-– REDUCED CLIMB PERFORMANCE– POTENTIAL ALTITUDE LOSS– REDUCED STALL MARGINS– SERIOUS CHANGES IN PITCH AND ROLL

RESPONSE


PILOT RESPONSE TO PILOT RESPONSE TO ONSET OF ICINGONSET OF ICING

INCREASE POWER- • USES MORE FUEL AND COULD EFFECT PITCH

CONTROL

MAINTAIN HIGHER SPEED & LOW ANGLE OF ATTACK-

• AVOID INCREASING COLLECTION AREA• AVOID SLOW AIRSPEED STEEP ANGLE CLIMBS• AVOID APPROACHING HIGHER STALL SPEED

DESCEND IF NEEDED TO AVOID UPSET


RESPONSE TO CONTINUED RESPONSE TO CONTINUED ICINGICING

ESCAPE! FOLLOW PRE-PLANNED EXIT STRATEGY

– CHANGE COURSE OR ALTITUDE – CLIMB IMMEDIATELY IF POWER MARGIN ALLOWS– DO 180 IF NEEDED – TURN AWAY FROM ICE PRODUCING CLOUD

STRUCTURES – DESCEND TO ABOVE FREEZING ABOVE MEA/MOCA– DESCEND IF NEEDED TO MAINTAIN CONTROL


STILL ACCUMULATING?STILL ACCUMULATING?

LAND BEFORE LOSS OF CONTROL OR UNCOMMANDED DESCENT!

DO NOT DEPEND UPON ICE PROTECTION SYSTEMS INDEFINITELY!

ESCAPE!


NASA VIDEONASA VIDEO

Discusses effect of ice on aircraft performance and control

Discusses appropriate pilot response to loss of control


WING

DIRECTION OF FLIGHTTAIL

DIRECTION OF FLIGHT


FLOW SEPARATIONFLOW SEPARATION


ROLL UPSETROLL UPSET

Collection efficiency- wingtip leading edge

Occurs more when slow and clean Separation Bubble forms Bubble moves aft and reduces ailerons

effectiveness


ROLL UPSET ROLL UPSET

CHARACTERIZED BY:– Uncommanded roll, aileron “snatch”,

neutral/reversed roll pressure

RELIEVE BY:– Increasing airspeed– Reducing angle of attack– Deploying flaps


TAILPLANE STALL / PITCH TAILPLANE STALL / PITCH UPSETUPSET

Collection efficiency- horizontal tail Occurs more when flaps are extended Separation Bubble moves aft and

effects elevators


TAILPLANE STALL / PITCH TAILPLANE STALL / PITCH UPSETUPSET

CHARACTERIZED BY:– Lightened pitch control, elevator pulsing,

porpoising, difficulty trimming, sudden and severe nose down elevator snatch

COUNTER-INTUITIVE RELIEVE BY:– PULLING back on yoke– Retracting flaps – Consider Reducing power and airspeed


PITCH AND ROLL UPSETSPITCH AND ROLL UPSETS

Ice Accumulation reduces controllable speed range

Auto-pilot masks onset of control issues Tail plane stall on short final may be

unrecoverable


REVIEWREVIEW

AVOID ICING CONDITIONS KNOW ESCAPE ROUTES UNDERSTAND CHARACTERISTICS OF

DANGEROUS ICING CONDITIONS AVOID USING FLAPS WHEN ICED KNOW UPSET RECOVERY TECHNIQUES


NASA GLENN HANDOUTSNASA GLENN HANDOUTS

CD ROM: INTER-ACTIVE TRAINING FOR G.A. PILOTS

DVD:– ICING FOR REGIONAL AND CORP PILOTS– ICING FOR GENERAL AVIATION PILOTS– SUPERCOOLED LARGE DROPLET ICING– TAILPLANE ICING

DOES STRUCTURAL ICE CONCERN YOU?

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