Winter Flying GAP

7/30/2019 Winter Flying GAP

1/16

Winter Flying


2/16

2

Winter in New Zealand brings an altered

operating environment.

New Zealand does not get the extremes of

weather that other parts of the world do,

but the temperature does regularly drop

below zero. Whether you operate from

these areas or are just planning to visit,

the following advice is equally relevant

to both xed-wing and rotary-wing VFR

operations.

Winter FlyingCONTENTS

Preparation............................3

IceProtectionSystems............6

Preight.................................7

Starting..................................8

Taxiing...................................9

Takeoff...................................9

InFlight...............................10

Landing................................13

Parking................................15

Conclusion...........................15

P

hoto:AirSafaris

Cover photo: Mount Cook Skiplanes


3/16

3

Preparation

Beforetheonsetofwinter,reviewthe

aircraftFlightManual,particularly

thesectionsrelatingtowinterisation

oftheaircraftanditssystems.Checkto

seeifyouneedadifferentgradeofoil

forwinteroperations.

Anyoutsideactivityinextremelycold

conditionswillbeuncomfortable,and

taskswillbedifcult.Yourpre-ightcheckislikelytobelessthorough.Slips,fallsand

minorinjurieswhileworkingaround

aircraftarealsomorecommoninwinter.

Heating and Defrosting Systems

Havetheheatinganddefrostingsystems

checked.Thisisparticularlyimportant

ifyouhaveacombustionheater.Itisgood

practicetocheckthecarbonmonoxide

(CO)emissionsregularly.Standardtests

willnotrevealtheconditionofall

partsinaheatingsystem.Theyneedto

beinspected.

Oneofthecheapestinsurancepoliciesisa

COdetector.Theyareasmallsensitivespot

thatwilldarkenwhenCOispresent.They

shouldbeattachedsomewhereinviewand

awayfromdirectsunlight.Replaceatthe

intervalrecommendedbythemanufacturer.

Ifyouarewet,yourbody,especiallyyour

feet,canbecomeverycoldwhenyou

climbtoaltitude.Notonlycanthiscause

hypothermia,butalsoitwillhavea

detrimentaleffectonyourabilitytoy

theaircraftandmakeasafelanding.Therehavebeencaseswherepeoplewith

verycoldfeetfailedtolandsafelybecause

theyweresufferingfromtheearlystages

ofhypothermia.

Removewetclothingifpossibleandtry

tokeepyourfeetdry,especiallyifyour

heaterdoesnotwork.Considerkeeping

somedryclothinginsidetheaircraft.

Mostimportantly,keepaclothhandyfor

demistingthecabinwindowsincasethe

defrostingsystemdoesnotworkproperly.

Fogged-upwindscreenshavecauseda

numberofincidentsinthepast.

Water Accumulation

Theexpansionthattakesplacewhenwater

freezesmaycauseconsiderabledamage

tointernalstructuresofwings,control

surfaces,orfuselagebulkheads.Evensmall

quantitiesofwateraccumulationmay

createastaticimbalancethatcouldseriouslyimpaircontroloftheaircraft.

Checkthedrainholesinthewings,

stabiliser,ightcontrolsurfaces,fuselage,

tailplanes,andairscoopstomakesurethey

areunobstructedandcapableofworking.

Aircraftthatareleftoutsideforanylength

oftimeinrainandfrostconditionswill

tendtoaccumulatewaterinallofthese

places.Itiseasyfordrainholestofreeze

over,keepingthewaterandicein.

Aircraftsystemsshouldbechecked

forwater.Asmallamountoficecan

preventtheproperoperationoffuel

pumps,selectorvalvesandcarburettors.

Pitot-staticsystemsshouldalsobe

checked,aswaterfreezinginthesecould

renderthealtimeter,airspeedindicatorandverticalspeedindicatorunserviceable.


4/16

4

Water in the Fuel

Inwinterthereisagreaterriskofwater

condensinginfueltanks;completelyfulltankswillhelpminimisethis.Fueltanks

shouldbecheckedforcontaminationby

drainingsomefuelintoatester.Checkthat

allfuelventsareunblocked.Ablockage

couldcauseanenginetostoporatank

tocollapse.

Fuelchecksshouldbecarriedoutafter

fuelhashadsufcienttimetosettle

afterrefueling.

Mud and Slush

Wheelspatsandfairingspickupmud

andslush,whichadverselyaffectstheoperationoftheaircraft.Ifmudisallowed

toaccumulateinthespats,itcanadd

considerableweightandcreateabraking

effectonthewheels.Theaccumulationof

compressedmudmayeventuallybreakthe

spatsiftheyarenotcleanedoutregularly.

Icebuild-upinsidewheelspatstendsto

breakupintoblocks,whichhavethe

potentialtojambetweenthewheeland

thespat.Checkspats,fairings

andundercarriagebaysforice

accumulationandmud.Clearout

regularly.Ifyouregularlyoperate

fromamuddyaerodrome,

considerhavingthespats

removedseasonally.

Cleaning

Operatingfrommuddy

aerodromesinwinterrequires

aircrafttobewashedfrequently.

Mudaddstotheweightof

anaircraft,aswellasdegrading

theefciencyoftheying

surfaces.

Bewareofwashingtheprotectiveagents

andlubricantsoutofhingesintheying

controlsandtrimmechanisms.Thiscould

allowwatertoenterandfreezeataltitude.

Replacetheprotectionbyeitherre-

greasingorsprayingonasuitablewater

displacinglubricant.

High-pressurehosesshouldnotbedirected

attheaircraftfrombehindthewingandtailsection,oraroundtheundercarriage

Photo:AirSafaris

Batteries

Afullychargedbatteryisessentialfor

winteroperationsandislesssusceptibleto

freezing.Lowtemperaturesmeanharder

starting,andthisimposeshighloadsonthe

batteryandelectricalsystem.Inextremely

coldweather,thebatterycanberemoved

fromtheaircraftwhennotinuseand

storedatroomtemperature.Theapplication

ofahighchargetoafrozenbatterymaycauseittoexplodesulphuricacid.


5/16

5

aswatercouldbecometrappedin

controlmechanismsandthenfreeze.

Thismaycauseproblemswithbrakesand

wheelbearings.

Ensurethatwaterdrainsawaybefore

youexposetheaircrafttofreezing

temperatures.

Ifyouraircrafthasaretractableunder-

carriage,checkthesystem,includingwheel

wells,forcontaminationbymudandslush.

CoverHangarageisthebestwinterprotection

foranaircraftbut,ifthisisnotavailable,

considerhavingwingandenginecovers

madeiftheaircraftistobepicketed

outside.Thesecoverscansavealotof

timeandhardworkwhenpreparingfor

ightafterfrostorheavysnowfalls.

Formoreinformationontiedown

procedures,refertotheSecure Your

AircraftGAPbooklet.

Personal Preparation

Warmclothingshouldbewornonwinter

ights,andgoodfootwearisamust.

Intheeventofaforcedlandingitmaybe

theonethingthatensuresyoursurvival.

Survival Kit

Acompactsurvivalkithasall-year-round

value.Akitcomprisingahuntingknife,

freeze-driedfood,lighterormatches,

ares,shingline,andasurvivalblanket,

canbepackedintoalightweightcontainer

thattakesuplittlespace.

Ensurethesurvivalkitisadequateforthe

numberofpeopleonboard.Consider

carryingemergencyclothingmadeofwool,whichisreasonablylightweightandre

resistant.Thesurvivalkitshouldalsoinclude

aninformationbookonsurvivaltechniques

anduseoftheequipmentinthekit.

Tiedowns

Goodtiedownsandpicketsshouldalways

becarriedwhenovernightingawayfrom

base.Thisisparticularlyimportantin

winter,whenfrontalweathersystems

aremorefrequentandharsh.Dontforget

toremovealltiedownsandpicketsbeforeying.

Pho

to:AirSafaris


6/16

6

Ice Protection Systems

Aknowledgeoficeprotectionsystems

couldbeusefultotheVFRpilotshould

theyinadvertentlyndthemselvesinicing

conditionsinanaircraftsoequipped.

Abriefdescriptionofthemostcommon

iceprotectionsystemsfollows.

FormoreinformationrefertotheCAA

Aircraft Icing Handbookavailableonthe

CAAwebsite,www.caa.govt.nz.

Pneumatic Boots

Pneumaticbootsarerubbertubesattached

totheleadingedgeofwings,tailplaneand

verticaln.Theyworkbyinatingand

crackingofftheice.Theymustbeoperated

bythepilotandaretime-criticalinthat

theymaynotworkiftoomuchicehas

beenallowedtobuildup.Iftoolittleice

hascollectedbeforetheyareoperated,

thenicemayformaroundthebootwhile

itisextended.

Nevertheless,pneumaticbootsarestill

themostpopulardeviceusedtoremove

inighticing.

Inight De-icing FluidsDe-icinguidsareoozedthroughperforations

orporousportionsontheleadingedges.

Thissystem,althoughveryeffective,isstill

rarebecauseofthecostsinvolved.

Propeller De-icing

Alcoholde-icingsystemsforpropellers

aresimpleandrequireminimalcare.Tubesemitliquidfromthepropellerhub

andrubberapronsdirectitalongtheblade.

Manypropellershaveelectricde-icing

systemsthatheattheblade,causingthe

icetoshed.

Windscreen De-icing

Windscreende-icersheateitherthe

windscreenoraportionofthewindscreen.

Theycanbeembeddedinthewindscreen

orattachedasanadditionalplate.

Rotor-blade Anti-icing Equipment

Rotor-bladeanti-icingequipmentisusually

anelectricalmatrixthatcoverspartofthe

leadingedgealongtheentirelengthof

theblade.Heatisphasedintothismatrix

indifferentsectorstoavoidlargechunksoficesheddingfromtheblades.
http://www.caa.govt.nz/http://www.caa.govt.nz/


7/16

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Preight

Beforeanyight,athoroughweatherbriengisessential,especiallyinwinter.

Carefullyconsiderthefollowing.

Departure weatherwouldyoubehappy

toreturnifyouhadto?Whatabout an

alternativeaerodromethathasbetter

forecastweather?Youmaybebetter

advisedtogotherethantoreturntobase.

Enroute weatherconsidertheeffectsonyourightofvisibility,cloudbase,

freezinglevel,potentialinductionicing,

andvariousformsofprecipitation.

Dontoverlookcurrentpilotreports

ofweatherhazards.

Destination weathercheckceiling,

visibilityandprecipitation,notonlyfor

yourdestination,butalsoforsuitablealternatives.Fogismuchmorecommon

inwinterandcanbeverywidespread,

potentiallycoveringthewholeofeither

coastoftheSouthIsland.Becausefog

occursunderananticyclone,itistempting

toassumethattheweatherwillbeclear

andne.Itisimportanttoobtainregular

weatherupdatesandaugment

thesereportswithinformationfromlocaloperators.

Nightightsareevenmore

limitedbyavailablealternatives.

Otherthingstoconsiderin

winterarethesurfacecondition

ofthedestinationaireldand

theamountofdaylight

remainingwhenyouarrive.Rememberthatthedaylight

becomesevenshorterwhenbadweather

setsin.ForVFRoperations,plantoarriveat

yourdestinationatleast30minutesbefore

EveningCivilTwilight.Thiswillgiveasafety

marginforunexpecteddelaysenroute.

Possiblediversionsaroundweathercan

considerablyaddtoighttimeand

increaseyourfuelneeds.Theuseof

carburettorheatwillprobablybemore

frequent,andthisalsowillincreaseyour

fuelconsumption.

Anywheresnowisfallingshouldbeavoided.

Snowwilltransformreasonablevisibility

inraintovirtuallyzeroinheavysnow.

Coverings of Snow, Ice, or Frost

Coveringsofsnow,ice,orfrostmustbe

entirely removedbeforeight.Itis

especiallyimportanttoremovesnow

beforeitturnsintoice.Atactileinspectionforiceshouldbeconductedbymoving

abarehandorathinlyglovedhandover

criticalsurfaces.Anycoveringoffrostis

unpredictableinitseffectandcould

adverselyaffecttheliftingcapabilities

ofanaeroplanewing.

P

hoto:AirSafaris


8/16

8

Forsmallaircraft,handbrushingwillclear

whatisnotstucktothesurface.However,

hardicewillnotberemovedbybrushing.

Patchesofsolidicecanthenberemoved

bysawingwithalengthofmaterialor

hempropebackwardsandforwardsover

thesurface.Hard-edgedtoolsmustnot

beused.Hot-airblowersaresometimes

helpful,buttakecarethattherun-offis

notallowedtopoolandfreezeunseen

overdrainageholesoraroundhinges.

Warmwatermixedwithde-icinguidcanalsobeused.Plasticcardsareparticularly

goodforwindscreens.

Snow,iceandfrostshouldbecompletely

removedfromhelicopters.Evenasmall

amountoficeremainingonaportionof

therotorbladescouldsetupavibration

thatleadstolossofcontrol.

Pitot-Static systems

Beforeight,ensurethatthepitotand

staticsourcesareclearofcontaminants,

thepitotcoverisremoved,andthe

pitotheadissecurelyattachedandfree

ofdamage.

Starting

SomeaircraftFlightManualsrecommend

pullingthepropellerthroughseveraltimes

withthemagnetoandmasterswitchesoff

beforestarting.Thisisintendedtorelieve

anypossiblecomponentstresscausedby

cold-thickenedlubricantsduringstart.

Thisshouldnotbedoneifthemanualdoes

notrecommendit.Theadditionalwear

onenginecomponentsrubbingwithoutlubricationcouldbeharmful.

Heatingpadsthatattachtothebottom

oftheoilsumpworkbywarmingtheoil

beforestart,andtheyareareasonably

cheapwayofraisingtheoiltemperature.

Inextremeconditionsitmaybenecessary

toremovetheoilandwarmit.Inthiscase,

ensurethattheoildoesnotbecome

contaminatedbeforeitisreturnedto

theengine.

Inwinter,startingrequiresmorepriming

inbothfuel-injectedandcarburetted

engines.Carburettedenginescanbe

particularlyhardtostart.Thereisan

increasedchanceofadditionalfueligniting

duringthestart.Bereadytotakeappro-

priateaction.ConsulttheaircraftFlightManualforre-during-startprocedures.

Inwintertheimportanceofcylinder-

headandoiltemperaturesaswellas

carburettorairheatcannotbeover-

emphasised.Warmingtheenginebefore

takeoffandallowingtheenginetocool

downpriortoshutdownpaysdividends,

especiallyatoverhaultime.


9/16

9

Taxiing

Associatedwithwinteraretheproblemscreatedbyice,snowandheavyrainon

runwaysandtaxiways.Taxionsnowand

iceasthoughyouhaveneitherbrakesnor

abilitytosteer.Stayoutofruts,puddles

andmudpatches,andwatchoutfor

heavyfrostoriceonsealedareas.

Itmaybenecessarytoplantotaxiand

takeoffveryearlyinthemorningbeforetheiceorfrostmeltsandturnsthe

aerodromeintoabog.

Freezingfogisnotuncommonininland

areasonwintermornings.Runningup

andtaxiinginfreezingfogcanleadto

largebuildupsoficeonpropellers.

Bettertoshutdownandtryagainlater

whenthefoghasliftedthantoattempt

adepartureinthissituation.

Windscreen Misting

Suddenmistingontheinsideofthe

windscreenisahazardthatcaneasily

catchpeopleout.Mistingcanbe

accentuatedwhenwarmbodiesindamp

clothingareonboard.Ifyourdemisterdoesntworkwell,makesureyouhavea

clothwhenyoudoyourpreightcheck.

Takeoff

Snow,slush,mud,andwetgrasswill

lengthenthetakeoffrollandmay

contaminateundercarriagedoorsandwheelwells.Thiscouldcausedamageto

theundercarriageonretractionand

couldincreasethelikelihoodofjamming

gearanddamagingstructures.

Itisrecommendednottotakeoffon

runwayscontaminatedwithsnowandice

unlessyouareproperlytrainedtodoso.

Itmaybeimpossibletomaintaindirectionalcontrol-especiallyingustyorcrosswind

conditions.

Snoworiceontheupperwingsurface

substantiallyreducesliftandincreases

weight.Theshapeoftheaerofoilisaltered,

anditbecomesmuchlessefcient.

Frostismoresubtlethansnoworice

buildups.Theaddedroughnessonthewing

uppersurfaceincreasesskinfrictionandTekapo runway newly cleared after an overnight

snowfall.

Photo

:AirSafaris


10/16

10

reducesthekineticenergyoftheboundary

layer.Flowseparationoccursatanangle

ofattacklowerthanthatofasmoothwing.

Whethersnow,iceorfrost,thestall

speedisincreased,andtakingoffwithout

removingallthesnoworiceshouldnot

beattempted.Thebeliefthatpropeller

slipstreamorairowoverthewingswill

blowthesurfacescleanisincorrect.

Takeoffonthedriestpartoftherunway.

Ifyoundthetakeoffperformancepoor,

preferablyabortearlyenoughtoenable

youtostopinthedistanceremaining.

Calculateadecisionpointwhichwill

allowsufcientrunwaytostoporfacilitate

asafetakeoff.Evenifthatisnotpossible,

itisstillbettertogothroughthefenceat

theendofthestripthantocontinuewith

atakeoffthatcannotbecompleted.

In Flight

Induction Icing

Inductionicingcanoccuratanytimeofthe

year.Carburettorheatoralternateairare

thebestdefenceagainstit.Thesesystems

shouldhavebeencheckedbeforetakeofftoensurethattheywerefunctioning

correctly.Inthecaseofcarburettorheat,

itshouldbeconrmedthatitsapplication

gaveanrpmormanifoldpressuredrop.

(Mostfuel-injectedengineshavean

alternateairsystemtted,which,when

selectedbythepilot,ductswarmairfrom

withintheenginecowling,thusby-passingthenormallteredairsource.)

Theengineinstrumentsshouldbe

monitoredinightforlossofrpm(xed-

pitchpropellers)orlossofmanifold

pressure(constant-speedunits).Anysuch

loss,orroughrunningingeneral,could

indicatetheformationoficeinthe

inductionsystem.

Foraircraftwithcarburettedengines,

applyfullcarburettorheatperiodically

duringthecruisetoavoidiceaccumulating,ensuringthattheselectionislongenough

totakeeffect(ie,20secondsormore).

If induction icing is present, the engine

may continue to run roughly for a short

time as the ice melts and is ingested.

Fullcarburettorheatshouldbeapplied

priorto,andduring,reduced-power

descentstopreventventuriicingcaused

bythereducedthrottlebutterysettingsinvolved.Theengineshouldalsobe

warmedperiodicallywithgradual

applicationsofpowerifthedescent

istobeaprolongedone.

Foraircraftwithfuel-injectedengines,

selectalternateairONifimpacticingis

suspected(suchasmaybeencountered

duringdescentthroughanareaofprecipitationabovethefreezinglevel).

Photo:Mo

untCookSkiplanes


11/16

11

AIR TEMP C

Carburettor Icing Chart

-10 0 +10 +20 +30 +40-20

100%

HUM

IDITY

o

-10

+10

+20

Fog

/Clou

d

DEWPOINTC

Serious icing - any power

Moderate icing - cruise poweror serious icing - descent power

Serious icing - descent power

Light icing - cruise

or descent power

Simplied views of a venturi

showing changes in air velocity

and temperature. These vary in

relation to changes in throttle

opening and engine rpm.

Float-type carburettors have a

fuel discharge nozzle located in

the venturi. Venturi action plus

cooling effect of fuel vaporisation

can reduce mixture temperatures

markedly.

The risk of serious carburettor icing

is greatest at lower or idle power

settings. When carrying out prolonged

glides, the engine must be warmed

regularly to provide sufcient exhaust

heat to the hot-air heat exchanger.


12/16

12

Alternateairshouldbeselecteduntilthe

aircraftdescendsintowarmerairand

theaccumulatedimpacticemeltsaway

fromtheengineairintake(s).

Inductionicingisalsoamajorproblem

inpiston-enginehelicopters.Unlike

aeroplanes,whichhaveapropellerthat

keepstheenginerunningifithesitatesor

coughs,helicoptershaveafreewheeling

unitorone-waydrive.Thereisno

inertiatokeeptheenginerunning.

Detectingtheonsetoficingismademoredifcultbythenature

ofhelicopterying,wherethe

numeroussmallchangesinpower

androtorrpmmasktheusualsigns

ofcarburettoricing.Carburettor

heatisusuallyeffectiveandshould

beusedwhenicingconditions

arelikelytobeencountered.

ChecktheaircraftFlightManual

forspecicinstructionson

carburettorheatapplication.

Helicopter Loss of Visibility

Flyingahelicopterwithobscuredvisibility

becauseoffog,snow,alowceilingorona

darknightcanbefatal.Helicoptershave

noinherentstability,andtheyrollandpitchatmuchfasterratesthanaeroplanes.

Lossofoutsidevisualreferences,evenfor

amoment,canresultindisorientation

andincorrectcontrolinputs.Thistypeof

accidenttendstobefatalbecauseofthe

highimpactvelocitiesinvolved.

Itiseasytorealisetoolatethatvisibility

hasbeenlost.Anyattempttoturnwithoutvisualreferenceislikelytoleadtoa

completelossofcontrol.Remainaheadof

youraircraft,andavoidareaswherethe

visibilityisobscured.

Unliketheaeroplane,thehelicopterallows

yougreateropportunitytolandanduse

alternativetransportinbadweather.

Useyourgoodjudgementandwillpower

tomakethedecisionearly.

Freezing Rain

Ifyouencounteranyformoficing

(themostlikelybeingfreezingrain)when

yingbelowcloud,vacatetheareaby

changingeitheraltitudeorheading.Freezingrainoccurswhenrainfroma

warmlayerofcloudfallsintoanairmass

thathasatemperaturebelowzero.Ifyou

happentobeyingthroughthisareait

islikelythatyouraircraftwillbequickly

envelopedinice(usuallyclearice)from

thefreezingrain.

Freezingrainisnormallyassociatedwiththecoldsectordirectlyundertheslopeof

Photo:AirSafaris


13/16

13

awarmfront,orinthecoldsectorjust

behindacoldfront.Sometimesitcan

occurwherethereisastrongtemperature

inversionandrainfallsfromwarmerair

ataltitudeintocoolerairjustabovethe

freezinglevel.

Snowfall

Snowmasksfamiliarlandmarks,making

navigationdifcult.Raincanturntosnow

veryquickly,causingasuddenlossof

visibility.Remainalerttotheoverall

weatherdevelopmentaroundyousothatyoucanreacttothepotentialhazard,

ratherthangettingcaughtout.

Whiteout

Whiteoutcanoccurwhensnow-covered

featurelessterrainblendsintoanovercast

(especiallyhighovercast)sky.Thehorizon

disappearsanddisorientationcanquicklysetin.

Maintaingoodvisualcontactwithwell-

denedobjects.Proceedonthebasisof

whatyoucansee,notwhatyoucannot.

Ifyoudobecomeunabletodistinguish

terrainfromsky,transfertoinstruments

andturnatrateonethrough180degrees

withoutdelay.

Landing

Fog

Fogcanbeverydeceptivefromtheair.Asyouyoverityoumaywellbeableto

seedownthroughit,becauseitisgenerally

onlyafewhundredfeetthick.Butonce

youstartanapproachtowardsthe

groundyouwillnolongerbeabletosee

horizontallythroughitanyfurtherthan

afewhundredmetres.

Somefogpatchesmaybeimpossibletoseeagainstanovercastday.

This shows how a

temperature inversion

at altitude can produce

conditions conducive to

freezing rain.

10,000

9,000

8,000

7,000

6,000

5,000

4,000

3,000

2,000

1,000

0

-15

-10

-5

0

5

0

-5

0

8

17

22

Temp(C)

Altitude(feet)

FreezingRain

Freezing rain associated with a frontal system inversion layer


14/16

14

Wet Surfaces

Anywetlandingsurfacewillincreasethe

distanceofthelandingrun.Itis,therefore,importanttolandattheminimumspeed

suitablefortheconditions,tominimisethe

landingdistance.Maximumbrakingeffect

willbeachievedifthewheelsarenot

locked,sointermittentbrakeapplicationis

moreeffectivethanapplyingfullpressure

andholdingit(thisdoesnotapplyto

anti-skidbrakingsystems).

Landings on Snow

Landingonsnoworiceisextremely

hazardousandshouldbeavoidedunless

youareproperlytrainedtodoso.It

increasesthedistancerequiredmarkedly,

andtheheaviertheaircraftthegreaterthe

increase.Intheseconditionsplanthe

landingasifyouwillbeunabletobrake.Touchdownattheslowestpracticalspeed,

neverlanddownhill,andduringthe

landingrunkeepstraightwithrudder

trytostayoffthebrakes.

Heavywetsnowofevenashallow

depthcanincreasethedragconsiderably.

Thiscanincreasethechanceof

overturningatailwheelaircraft.

Extremecautionshouldbeexercisedwhen

landinghelicoptersonsnow,particularly

atanunfamiliarsite.Theremaybedoubt

aboutthedepthofsnowandthecondition

oftheunderlyingground.Theweightof

theaircraftshouldbetransmittedtothe

landinggearcarefullyandgradually,

testingthesitesabilitytotakeallthe

weight.Bereadytoliftoffimmediately

thereisanydoubt.

Softpowdersnowwillwhipupin

therotorwashanddestroyvisibility.

Approachsnowverycarefully,especiallyinpowderconditions.


15/16

15

Snow Ingestion

Snowingestionintohelicopterturbine

enginescancauseaameout.Aparticleseparatorcanpreventthisbutisalso

subjecttoicingandbecomingblocked.

Theamountofsnowingestioncanbe

controlledtosomeextentbycarefulying.

Hoveringoverloosesnowshouldbe

avoidedwhereverpossible.Inthese

conditionsapositiverateofclimband

forwardspeedshouldbeattainedimmediatelyafterliftoff.Anormal

approachforlandingonsnowshouldbe

onecontinuousoperationtotheground,

withouthovering.

Apartfromthepossibilityofaameout,

unnecessaryhoveringcanalsocause

spatialdisorientation.Duringthe

approach,ifthelandingareaorreferencepointstartstobecomeobscure,an

immediatego-aroundshouldbemade

ratherthananyattempttohoverand

reorientyourself.

Parking

Topupthefueltanksafterightto

minimisetheriskofcondensationforming.

Iftheaircraftistobeparkedoutside,

usecontrollocks,andtieitdownsecurely

togoodpickets.Ifcoversareusedfor

engines,air-conditioningsystemintakes,

pitotandstaticsystemopenings,orram-

airinlets,makesuretheyarehighlyvisible

sothatyoudontforgettoremovethembeforethenextight.

Whenparkingovernightinareaswhere

thereissnowfalling,bepreparedtosweep

thewingandtailsurfacesatregular

intervals.Thisistoavoidexcessiveweight

onthewingandtailplane(somesnowcan

beverywetandheavy).Takecareinwhere

youplaceyourpicketsaheavysnowfall

couldcausetheaeroplanetositonitstail

andpotentiallyitspicket!

Conclusion

Winteryingcanbeaspectacular

experience,especiallyinthesnow-covered

SouthernAlps.Inordertokeepitsafe

thinkahead,andbefullypreparedbeforeventuringoutintothewinterweather.


16/16

Winter Flyingwas revised in June 2010.

See our web site, www.caa.govt.nz, for details of more CAA safety publications.

P O Box 31-441

Lower Hutt 5040

Tel: 04560 9400

Fax: 04569 2024

Email: [email protected]

Documents

Winter Flying GAP