TCAS Philosophies

8/19/2019 TCAS Philosophies

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TCAS II AS in ertical plane! TCAS III AS in both erticaland hori$ontal plane" +ork on TCAS III stopped as the logicproed too comple#! and ertical plane As were moreeffectie at aoiding a collision" So there will most probablyneer be any TCAS III "

This is the situation today "

2ow .uestions asked were , is a new Ueberlingen possibletoday ,

+ith TCAS sense reersal logic flaws , yes ! nothing haschanged since 4''4" same logic" Same ersion flying around)0"'*"+ith procedures , maybe , ICA: has reised itsdocumentation and most training material hae highlightedthe way to follow in case contradiction between ATC clearanceand A" ?ut incident statistics so far both from USA and%urocontrol show that some controllers still issue clearancescontrary to As and that pilots still choose to follow ATCinstead of A") a recent case in /rance! with US trained and e#perienced080 pilots from a ma6or US airline ! so no need to think it onlyaffect e#otic or ussian pilots *=ain reason , lack of understanding on how humans andautomated machines function in reality" Prof 7adkin in hise#cellent paper http,99www"rs"uni-bielefeld"de9publ"""rts9SCSS';"pdf on causal analysis afterUeberlingen call this “ Sociotechnical systems “ "

2ow a last statistic , ) coming from ?ill Thedford! of the?oston =IT 77C! one of the top 34 in my first classificationearlier* Ueberlingen type encounters ) sense reersal * occursat ;"0 # 3' to the minus 8 per flying hour ! or &@ eents ayear in %urope "If we e#pand this model! ?ill predict that wecould hae 3 Ueberlingen type mid air collision eery ; yearsdue to the logic flaws"

The conclusion of this all ,Bo not philosophy about TCAS , It is too comple# a system"=y adice , if you are a pilot , follow the A! and if you are acontroller and you hae to gie anti collision instructions !

gie a turn as well! in case TCAS comes in ! it willcomplement your instruction instead of nullify it"

If you found this too long ! this was the ) ery* short ersion"Safe flying"

11th September 2007,10:23

#8 (permalink )

P?7

oin Bate, Sep 4'''7ocation, ?ielefeld!

Duote,

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EermanyPosts, &&F :riginally Posted by airmen, referring to TCAS

they saved already my live once at least!

T

here is a phenomenon here worth thinking about"+hen I oiced some of my concerns about TCAS on apilotGs mailing list some years ago! I was delugedwith affidaits from pilots who claimed that TCAS hadsaed their lies" If all of these claims had been true!that would hae amounted to some 4' or so midaircollisions in a sample of a few hundred pilots )themembers of the mailing list* oer the course of! say!ten years" 7etGs assume 3' Hlife-saersH! that is!otherwise-midairs! for &'' pilots in 3' years" That isan aerage of one Hmidair collisionH per &'' pilotsper year"

There are about 3&!''' aircraft from Airbus! ?oeing!

=B! 7ockheed still in serice )calculated from figuresin /light International! 4;->' :ctober 4''8*" SothatGs not counting the HcommutersH! or theTupoles" Those aircraft are in serice! letGs say! 3;hours per day! for a total of 43'!''' hours per day!or &!@@'!''' hours in 4@ days" Buty rosters take 3''flight hours for a pilot in 4@ days to be relatielyhigh! but letGs use this figure! since it will lead to aconseratie estimate" It means there are about&F!''' captains needed to fly those &!F''!''' hourseery 4@ days" +ith one HmidairH per &'' captainsper year! and accounting for the fact that it takes 4

captains to hae a HmidairH! we come to a figure of&F HmidairsH per year"

Compare this with actual midairs amongst airlinetransport aircraft" 3F&F Erand Canyon! 3F08 agreb!3F0@ San Biego! 3F@& Cerritos" And then! since theadent of TCAS! 3FF& 2amibia )inoling a Eermanmilitary machine which I do not beliee was TCAS-e.uipped*! 3FF8 2ew Belhi! 4''4 Jberlingen and4''8 Ama$onas" That is ; before the adent of TCAS)mandated 3FF3! I beliee* and ; since )38 years*"

Those crediting TCAS with all these HsaesH need toe#plain why! before the adent of TCAS! there were astatistically-negligible number of collisions in thehistory of airline flying! and upon the introduction ofTCAS there are suddenly almost 8' per year" %enconsidering the growth of air trael! that is anunbelieable 6ump"

The obious answer is! of course! that most of thoseHsaesH would not hae resulted in collisions! despitewhat their pilots thought or think"

Consider the following! as a thought e#periment" Upto the Congressional mandate for TCAS! there were


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three collisions inoling airliners in the U"S", 3F&FErand Canyon! 3F0@ San Biego and 3F@& Cerritos"Suppose TCAS initiated As! not for 4 TCAS-e.uippedaircraft! but only when one had TCAS and the otheronly =ode C" That would hae satisfied the issue

worrying the Congresspeople! namely incursions ofEA aircraft into $ones of intensie airline operations!and it would hae saed one of the midairs since)Jberlingen*" The other three midairs in the TCASera occurred to non-TCAS-using aircraft"

7et us compare TCAS with another highly-laudedsystem for aoiding accidents! EP+S9%EP+S" Also asystem introduced primarily by one manufacturer)again Koneywell*" And in contrast to TCASaddressing a real! continuing problem which stillleads to many aircraft losses per year! namely C/IT"%EP+S is essentially a priate deelopment)stemming from the work of Bon ?ateman andcolleagues*"

It is interesting in this regard to notice how TCAS isself-adertising and %EP+S not" A pilot can sayHTCAS saed meH without it reflecting on himher self!but rather on some air traffic controller establishmentsomewhere" 2o pilot can say H%EP+S saed meHwithout someone else asking how heshe lostsituational awareness in the first place )with raree#ceptions in which it is clear how! such as with?ritish =editerranean at Addis Ababa*"

So the statistics were neer there to say HTCAS is agood thingH! and it is self-adertising! through pilotHsaeH stories" ?ut there are smart people inaerospace who! no matter whether they think TCASis a net gain or a net problem! are able to look at thefacts and the situation 6ust the same as I am now"Airline C%:s! for e#ample" So the .uestion is, whyare collision aoidance mechanisms still beingpromoted! researched and supported to such a greate#tentL

I think there are two reasons" :ne is that they areone attempt at a solution to a problem which no oneknows yet how to assess accurately! namely theaoidance of midair collisions! and no one is willing torisk mis6udging )underestimating* the likelihood ofthose" The other reason is that effectie on-boardsystems make collision aoidance a contract betweenthe two )or more* aircraft inoled! which transfersthe costs of collision aoidance away from large ATCorganisations" Since the airlines and their passengersultimately fund these organisations! one could seethe financial benefits to airlines of bringing this

function in-house )after the initial cost of installingthe e.uipment! which has n any case been


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mandated*" Add to this that collision aoidance is oneof the brakes on moing to Hfree flightH )self-routingI/ at high altitudes*! which airlines beliee wouldbring them great cost reductions! and one can seethat TCASMfree flight is a politically sellable package

which could reduce the costs of air trael eenfurther" +ithout some ATC-independent collision-aoidance system regarded as effectie! this moecould not happen! and TCAS is the only technology intown"

P?7

airmen

oin Bate, 2o 4''47ocation, planet hearthPosts, 33'

TCAS is designed to work according manufacturermanual! it is stipulated here that pilots hae to follow

orders to escape! so why argue with that and preferto follow ATC ordersL=aybe those guys need to hae a good Sim sessionto understand by doing it wrong to be able to learnsomethingL

P?7 wrote,Duote,

The obious answer is! of course! that most ofthose HsaesH would not hae resulted incollisions! despite what their pilots thought or

think"

I

saw the conflicting aircraft )a ?eech ?aron* at thelast minute )sun in the back* during the escapemanoeuer! he was ery close and was flyingopposite course at the same altitude )controllererror* and I can tell you that the controller went byhimself to meet us after landing! he told us that hesaw nothing and as such gae us no instructions" :ffcourse we followed the TCAS but I can not tell youwhat the other pilot did"""

Last edited by airmen : 12th September 2007 at

07:44.

12th September 2007, 10:05 #19 (permalink )

ATC +atcher Pegase Brier oin Bate, =ay 3FF07ocation, %urope

Age, &FPosts, 3!'&4

The " value of X "

Duote,

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:ne of the main issues withTCAS! for me! is that no oneknows what the alue of N is"

I

ndeed ! and that debate is hinderingthe obious solution to ourproblems , making the A acommand! i"e" an obligation tofollow in all circumstances"In the US! at its conception !the=IT%9/AA 7awyers preented thisand insisted we call the TCASaoidance resolutions G Adisories Hand not H CommandsH therefore it iscalled an A"

?ut besides this H alue of N H

technical issue ! there are otheraspects as well"I always refer to the H Eermanglider H one ! following apresentation by a famous Eerman0;0 Capt in ICA: , to e#plain whyhe will neer agree that followingA a should be re mandatory in allcases he said ,!I am in I/ in class E airspace andI get a climb A ! but 6ust aboe meare gliders without transponders !

my first duty as Captain is tomaintain the safe operation of myaircraft and stay below the gliders !therefore I will elect not to followthe A in this case"And he is right" So an adisory itremains"

Duote,

TCAS is designed to workaccording manufacturer manual!

it is stipulated here that pilotshae to follow orders to escape!so why argue with that andprefer to follow ATC ordersL

I

ndeed why argue L =ainly for 4reasons , one is human , peoplereact differently to automation thatothers and culture also plays a role"PPu2e is full of discussions on thisissue " Studies shows that een aswe speak today >' to ;'( of the H

Ad6ust ertical speed H As are notfollowed by pilots" ) it used to be


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8'( > years ago * " So it is not onlyATC H interferenceH"

The other reason is the risk ! the Halue of NH mentioned aboe" If it

would hae been all without risks! !coupling the As to the auto-pilotswould hae resoled the issue andwould hae been done"

12th September 2007, 10:06 #20 (permalink )

P?7

oin Bate, Sep 4'''7ocation, ?ielefeld! Eermany

Posts, &&F

Duote,

:riginally Posted by airmen TCAS is desined to or"

accordin man#$act#rer man#al%it is stip#lated here that pilotshave to $ollo orders to escape%so hy ar#e ith that and

pre$er to $ollo ATC orders&

Pl

ease read my analysis of thedecision problem presented to the?akshirian crew at Jberlingen" Theywere faced with an HintruderH at 3'oGclock which they saw! and anunknown conflict at 4 oGclock whichthey didnGt see! and for which they

had an adisory to descend )that is!he was at or aboe their altitude*"

+hat would you doL Climb towardsanother conflicting aircraft that youdonGt see but ATC doesL :r aoidhim! descend towards an aircraftthat you do see! and hope to aoidhim using isual meansL

Please gie some good reasons foryour answer that will also be good

reasons for any other pilot in thissituation"

Duote,ThatGs ery interesting and I agreewith you that it counts as a sae)but of course it doesnGt contradictmy obserations on claimedHsaesH*" I hae a number ofobserations"

/irst! ?eech ?arons donGt hae TCAS

)I donGt know that the aionics areapproed for installation in a ?aron!

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2ot that I disagree with the broadthrust of what you are saying"

pb


#37 (permalink )

alf&'03h

oin Bate, ul 4''>7ocation, An IslandProincePosts, 8;F

Peter! the 5EP+S situation is more comple# if youconsider %EP+S which uses a database andnaigation position in its computation" Oou mayhae meant this but your response related toEP+SQ as you realise! it is important to distinguish

between the two" This is particularly so for the crewas the later system )%EP+S9TA+S* is morecapable and reliable than preious systems! butthen opens greater opportunity for error due to therange of alerting and warning modes and theterrain display! e"g" during an approach a pilot maypull up in response to a warning and incorrectlyleel at =BA! but due to a )gross* error in range!=BA is not safe"

Also note that some ersions of %EP+S use EPSaltitude as a gross error check of altitude! mainly

incorrect pressure setting" EPS )geometric* altitudedoes not replace the rad alt )there are e#ceptions*as its accuracy is less than that of normal altimetry!and therefore at this time it would not be acandidate for ACAS altitude as suggested earlier inthe thread"

As for the solution to the three aircraft ACASproblem! this is done reasonably successfully bycombat pilots in 3 s 4 situations" =y e#periencesand e#istence today is releant! but based on thesame e#periences I would be less confident forsituations inoling ; s ;! due to the humanlimitations in continuously computing a ;B )space time* solution! thats assuming that you can seeeeryoneR

Oour ACAS problem relates to a similar ;B situationand thus might be modelled in the form the ;thpower"Considering three aircraft aoidance! #! y and $!then a solution could be in the form of #; y;M $;"This form of e.uation for powers greater than 4 hasbeen proen to hae no solution )/ermats

con6ecture*" +ith appropriate deductie logic! 5nosolution relates to a collision condition! thus I claim

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my PhB R

17th September 2007,

22:01

#38 (permalink )

ATC +atcher Pegase Brier oin Bate, =ay 3FF07ocation, %uropeAge, &FPosts, 3!'&4

Duote,

If this thread was about a crewGs response to aEP+S alert, H+hoop +hoop PU77 UPRH! whichinoled pushing the stick forward instead ofback! would there be much in the way oftechnical discussion re.uiredL

I

nteresting point "?ecause ! if we go back in time!there are similarities indeed " If one remembers theintroduction of EP+S! the early systems were prone

to many false alarms! which worked against crewacceptation" ) remember for instance the Air Interdecision in /rance with their new A>4' fleet! and thediscussions that followed after their =t St :dileC/IT *I do not hae precise archie data at hand ! but Iremember there were .uite a few C/IT accidents inthe late @'s 9early F's ! where EP+S alerts wereignored by pilots" ) the Independent air ?oeing 0'0in Santa =aria 9A$ores in 3F@F ! or the ThaiInternational A>3' in atmandu in F4 are 6ust twothat come to my mind for instance *

So the “ philosophies 5 ) how to deal with automation* do apply for both systems! in their early phases"In 4''0! EP+S ! and especially %EP+S could beconsidered mature" 2ot TCAS"TCAS is! despite its age! still in its early phase ! aswe now on ersion 0"' of its deelopment! and thatafter a collision and a good do$en of ery!ery nearcalls ! we are most probably going to hae a ersion0"3 in a few years" That might resole partially theflaws that contributed to those accidents9incidents"+hat we do in the meantime) i"e" until that newersion comes * ! is part of the debate here"


#39 (permalink )

/ull+ings

oin Bate, Bec 4''>7ocation, Tring! UPosts, ;>4

P?7!

Duote,I agree with 3" to >" but would you agree that ;" islikely to happen near an airport )you hae toapproach the ground when landing and get near it

when taking off* and airports are well known asplaces where aeroplanes like to congregate""" Anyway!

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the points IGm trying to make are,

a* EP+S and TCAS )and to a lesser e#tent %EP+S*are last-defence systems! conceied to possibly stop9reduce the chances of an accident occurring"

They are not designed or certified to replace ATC orgood piloting - e#cept at the last minute when eitheror both hae been lacking"

so!

b* As the alerts9adisories9warnings gien by theaboe e.uipment are somewhat time constrained intheir period of usefulness )R*! then a consistentresponse oer a short period is re.uired to allow thesesystems to function as intended! i"e" you canGtpontificate at great length about what action to take,it must be a memory drill - Hrecall itemH" And youhae to perform it correctly"

Duote,I assume that is the Jberlingen scenarioL I say that itwas the worst possible because it led to a collisionQalmost by definition any other action would haeproduced a HmissH" I know this is slightly simplistic butif you think about it in reerse! to generate a HhitHboth aircraft hae to occupy the same small spaceoer the same ery small time period" Any changes tothe tra6ectories of either will .uickly disrupt thismeeting" /inally! itGs because the manual says,

HNEVER MANOUVER AA!NST AN RAH"

Duote,

Those are not the only two options" Another ariseswhen you hae an adisory to manoeure to aoida conflict from same-leel or higher! and you haean aircraft below you in sight" +hat would yourdecision be and whyL

/

ollow the A" The danger in aiation comes mostlyfrom the aircraft you canGt9haenGt seen or arenGt

aware of" I would posit that you are unlikely to hit anaircraft that you hae in plain sight as you can tell if itis on a constant relatie bearing or notQ also you haethe option of a lateral manoeure to de-conflict" If thea9c below has TCAS! there might be coordinationgoing on that you are unaware of" If it doesnGt! thentheyGll )like you* probably follow the rules of the air toaoid a collision )if theyGe seen youR*

I find detailed technical discussions about most thingsto do with aiation absolutely fascinating""" but the 6obhas shown me that for some scenarios! you hae to

hae a fairly rote response prepared for immediateuse" I applaud scientific e#amination of the limits of


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aircraft systems but when you get to FF"FF(confidence )or whateer* in a particular one!especially if it inoles time-critical warnings! you 6usthae to say, HIt works! do what it saysH as there isnGtany room left to do a risk analysis on an alternatie

response"

I hae had seeral AGs in real life! one caused by anaircraft directly aboe deciding to descend at a greatrate through our leel" Bid TCAS sae our liesL BonGtknow but it was fVVVing close when we did eentuallysee it"


#40 (permalink )

mono

oin Bate, /eb 4''47ocation, UPosts, >F8

Bynamite!

I will try to answer a couple of your .uestions"

%P as you correctly state is a measure of the thrustproduced by a et engine" It is! as its name implies! theratio of what comes out the back oer what comes inthe front" The inlet pressure P3 is sensed by a singleprobe )like a pitot probe*! which is usually inside theengine inlet cowl! but can be on the spinner )?040* orthe pylon )?0'0*" The e#haust pressure P0 is sensed bya manifold or rack of tubes with holes in the 6et pipe"

In the main all %P indicating systems will! assuming T:power is acheied before the a9c is rolling! show adecrease in %P as the a9c accelerates down the runway"and this is .uite simply because the pressure at the inletprobe increases as the ram air effect is sensed at theprobe" A9c with the probe mounted in the inlet will onlyshow a small decrease because the probe also sensesthe pressure of the air being sucked into the engine" Theold 0'0 howeer! with its probe mounted on the pylon!away from the air being sucked into the engine used toshow a marked reduction in %P as it trundled down therunway"

Cost inde# is a figure proided for the a9c usually by theairline planning and performance dept" I canGt gie youany specifics! but it is used by the /=C to computeoptimum climb and cruise performance leels" A lowcost inde# will cause the /=C to calculate performanceleels to proide a lower fuel burn" +ith a higher costinde#! fuel burn becomes less important and speedyenroute times more important" The final figure is acompromise between fuel burn and enroute time andmay change depending on the route being flown"

I2S! ahh! that old chestnut" The first and mostimportant thing to realise is that neither I2S or IS use

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gyros to sense north" The gyros are merely there toeither electronically or mechanically maintain theI2S9IS platform leel and aligned with true north"

The system senses north in the following way,- there

are > sensitie acceleromerers each aligned F' degreesrelatie to each other" +eGll call them the ertical! lateraland hori$ontal accelerometers" Buring the initialalignment process! the outputs are used to calculate theertical a#is )in the old I2S systems the platform wasactually moed by motors so that the erticalaccelerometer was physically aligned with the ertical*":nce this is known then the outputs from theaccelerometers are used to sense acceleration forcesdue to the rotation of the earth and it is the resolution of these forces that aligns the I2S along the truenorth9south a#is" 2ote that due to the obious e.uitorialambiguity )acceleration forces at ;' degs 2 and ;' degsS are the same* it is not until the a9c present position isput into the I2S that true north is known"

Kope this helps

17th January 2003,23:11

#3 (permalink )

2otso /antastic

oin Bate, Aug 4'''7ocation, UPosts, 3!@3;

Interesting .uestionsR =aybe the %P does change"

2eer been looking at it to notice" :n the ?oeings IGeflown! autothrottle sets the re.uired thrust and ihaenGt been aware of it modulating the thrust leersto maintain constant thrust" I think any change on bigfan engines must be ery minor"Duestion &- back in the 0's I was dragged out onstandby to copilot a Certificate of Airworthiness teston a


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about 4' degrees latitude from the Poles! the I2S setswould hae difficulty aligning themseles" Used totake Classic 0;0s about 4' minutes! the ;'' ersionabout 0"

2nd Deember 2002,17:01

#8 (permalink )

2one

oin Bate, ul 4'''7ocation, +estPosts, >;&

I am going to training this week! so I thought Iwould look into this .uestion" ?elow is from the USAeronautical Information =anual )AI=* Chapter ;"

;-;-33" SP%%B ABUST=%2TSa" ATC will issue speed ad6ustments to pilots ofradar-controlled aircraft to achiee or maintain

re.uired or desire spacing"

b" ATC will e#press all speed ad6ustments in termsof knots based on indicated airspeed )IAS* in 3'knot increments e#cept that at or aboe /7 4;'speeds may be e#pressed in terms of =ach numbersin '"'3 increments" The use of =ach numbers isrestricted to turbo6et aircraft with =ach meters"

c" Pilots complying with speed ad6ustments aree#pected to maintain a speed within plus or minus3' knots or '"'4 =ach number of the specified

speed"

IGm uncertain of its applicability outside of the USA"

29th !u"ut 2002,17:11

#3 (permalink )

cwatters

oin Bate, Bec 4''37ocation, %nglandPosts, F40

+ings with a lot of sweep need less dihedral becausethe sweep contributes to roll stability )donGt as me

how! I donGt know*" If you hae too much roll stabilitythe plane canGt turn fast so they reduce stability to asatisfactory leel by giing swept wings anhedral"

Paragliders hae anhedral for a different reason - tohelp keep the wing open I beliee"

29th !u"ut 2002,18:08

#4 (permalink )

erik cwatters!

Swept wings improe ire#tional stability"

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15/22

oin Bate, =ay 4''37ocation, 2etherlandsPosts, 333

/or e#ample! yawing to the right causes the left wingto be positioned more perpendicular to the incomingairflow" This in turn increases the drag of the left wing!causing the a9c to yaw back to the left"

%rik"

29th !u"ut 2002,19:39

#5 (permalink )

eith"+illiams"

oin Bate, Aug 4''37ocation, Borset

Posts, &F0

Parapunter

The aboe replies are correct! but oerlook the specificproblems facing the harrier designers" In order toproduce efficient ertical thrust! the gas flowing from

the engine no$$les re.uires a reasonably clear pathertically downwards" This re.uired the use of highwings" ?ut high wings combined with a fairly high wingsweep angle would produce unacceptably strong lateralstability" The addition of anhedral both on the wingsand tailplane! reduced the larteral stability! therebyrestoring a reasonable degree of roll response"

29th !u"ut 2002,22:04

#6 (permalink )

ohn /arley

$o a %over & itavois

oin Bate, :ct 3FFF7ocation, Chichester+est Susse# UAge, 08Posts, 3!'FF

eith

I hae grae reserations about sticking my nose in onthis one! but for the first time eer I could find myselfat odds with something you hae posted"

Oour last sentence was “The addition of anhedral bothon the wings and tailplane! reduced the lateral stability!thereby restoring a reasonable degree of rollresponse"1

I can only agree with this if the roll response you .uoteis that due to a lateral gust" If it is the roll responsedue to aileron deflection that you mean! then Idisagree"

The rate of roll that happens following ailerondeflection on any aircraft has much more to do withthe roll damping of its wing rather than any lateralstability it may possess" Static lateral stability of thesort produced by dihedral :27O produces a stablerighting moment )that opposes ailerons* if sideslip alsodeelops from the side of the down going wing"

It is the need to obtain a reasonable )as opposed tohuge* response to a lateral gust that leads people to

http://www.pprune.org/615376-post5.htmlhttp://www.pprune.org/tech-log/65099-dihedral-anhedral.html#post615376http://www.pprune.org/members/37043-keith-williams-http://www.pprune.org/615512-post6.htmlhttp://www.pprune.org/tech-log/65099-dihedral-anhedral.html#post615512http://www.pprune.org/members/9046-john-farleyhttp://www.pprune.org/615376-post5.htmlhttp://www.pprune.org/tech-log/65099-dihedral-anhedral.html#post615376http://www.pprune.org/members/37043-keith-williams-http://www.pprune.org/615512-post6.htmlhttp://www.pprune.org/tech-log/65099-dihedral-anhedral.html#post615512http://www.pprune.org/members/9046-john-farley


16/22

employ anhedral" +ithout it an aircraft with a highwing and low CE! especially if the wing is also swept!will hae a terrible )huge* tendency to roll when hit bya lateral gust" So whether it is a 3;8 )where you areconcerned about passenger comfort as well as

controllability on a gusty approach* or a Karrier )whereaiming steadiness and low leel ride are theconsiderations* the answer is to include a rollingmoment due to sideslip that has the oppositearithmetic sign to that coming from sweep plus highwing and low CE" This means anhedral"

Oou can een use huge lateral stabilty to generate highroll rates" 2early ;' years ago as a ery new tp 6ustposted to Aero /light I was gien the S?& )7ightninglook alike with a tiny donk and a fi#ed gear* to fly onan open day" All of the e#perienced guys haingdeclined to be seen dead in the deice picked rathermore manoeurable mounts )like the /B4 or theKP33&* :n my first flight I found why, the stick forceswere huge! the rate of roll from aileron was negligible)thanks to them being unpowered! ery close to thefuselage and being almost too heay to deflect*" ?utthe monster had a sweep of 8'deg so this huge lateralstability enabled a modest facsimile of a twinkle roll tobe produced by kicking the rudder and makingdeliberate use of the huge rolling moment due tosideslip"

egards

ohn

30th !u"ut2002, 12:45

#7 (permalink )

=ark 3

oin Bate, Aug 4'''

7ocation, +arwicks! UPosts, 8&4

As far asolls-oycego! this

seems aeryconfusedsub6ect"

/rom what Iunderstandthe ?series wereoriginated in?ristol!although

their is noB series for

http://www.pprune.org/616221-post7.htmlhttp://www.pprune.org/tech-log/65099-dihedral-anhedral.html#post616221http://www.pprune.org/members/18914-mark-1http://www.pprune.org/616221-post7.htmlhttp://www.pprune.org/tech-log/65099-dihedral-anhedral.html#post616221http://www.pprune.org/members/18914-mark-1


17/22

Berby" The433 was 6usta se.uentialmodelnumber!

most ofwhich neersaw the lightof day" The-&4;followedfrom the-44! I thinkthe &indicated itwas &'!'''lb thrustclass!although the-&>& wasonly)originally*>&'''lbclass" Theother lettersreferred tothrottle-push orgrowthariants of

the sameengine"

As to whythe ?433didnGt getnamed aftera ma6orrier )as inSpey! Bart!Tyne! Trentetc"*! IGe

neer heardane#planation"

4th !u"ut 2002,19:07

#4 (permalink )

?abi =elayu

oin Bate, /eb 4''37ocation, =alaysia

Please donGt call yourself a retard"

Oou might be familiar with the more common >-degree

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18/22

Posts, 3> glideslope or gradient of &(" The &( means & 9 3''! &feet lost ertically )y-a#is* for eery 3'' feet traelledhori$ontally )#-a#is*" +hen you intend to find the anglesubtended by this & )y-a#is* and 3'' )#-a#is*! you 6usttake the inerse tangent of them both - opposite oer

ad6acent i"e" inerse tangent of & 9 3''" The result is anangle of 4"@> degrees ) which is close to the >-degreewe mentioned*"

The T+%7


19/22

oercomestiction 9frictionwithin themechanism!

i"e" cogs anda suitablesystem ofleers andpulleys etcbetween thecapsule andtheindicatingneedles"

+ithout itan altimeterneedle maylag 9 6umpand operatein HstepsH" Aibrator 6ustsmooths outthemoementof theneedle" 2otethat it isnGtoften

necessary tofit one tohelicoptersor pistonengineaircraft thatibratethroughothermeans"

14th January2002, 12:06

#7 (permalink )

Shore Euy

oin Bate,ul 4'''7ocation,U"S"A"Posts, ;'0

In one of my first )in person* introductions to the great dry?ritsh wit! I was in Sim 3! Bay 3 on the ?A-3;8 at Katfield"Instructor in the back! using his pointer to go oer all theinstruments! switches! indicators )retired ?A fellow as I recall*"

Ke pointed at a red flag in the standby attitude indicator! and

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20/22

said HItGs time to get out the flight attendants emergencychecklist - it seems our ibrator is inoperatieH"

8th $ebruary 2001,

12:00

#5 (permalink )

?:I2E

Posts, n9a If you want a .uick mental conersion that works.uite well at lower altitudes"

TAS IAS M )IAS98' # Kt )in thousands of feet**

I% TAS 4;' M )4;'98' # 3'* 4@'

Try it and see if the answers are close enough for youruse"

------------------

9th $ebruary2001, 05:16

#7 (permalink )

T:EAXParty

Posts, n9aSmurf6et!2ot so much a formula as a Grule of thumbG" +orks whenconditions are close to ISA and at altitudes not flight leels"

The TAS and IAS will ary by 3"@ kts93'''G"

eg" If weGre cruising at 3'G''' and indicating 3;&kts thenTAS will be 38>kts"ie 3"@)kts93'''G*N 3')lots of 3'''G* 3@kts

3;&kts )IAS*

M3@kts 38>kts )TAS*

Also works 6ust as well the other way aroundRR

10th $ebruary2001, 18:08

#8 (permalink )

fart

Posts, n9a This will gie you a .uick answer that comes faily close to

the real deal,

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21/22

Use 4( of IAS per 3''' ft and add to IAS,

%#ample, IAS is 4'' nots at 4& ''' fttherefore 4( N 4&''' diide by 3''' 4& &'( of IAS

&'( of 4''nots M 4'' 2:TS 3'' M 4'' >'' nots TAS

22nd $ebruary 2001,15:22

#3 (permalink )

Tinstaafl

Posts, n9a I know itGs a bit pedantic but I know that rule ofthumb as TAS 93' M 0! not !AS"""

24th $ebruary 2001,05:51

#7 (permalink )

Ban +interland

Posts, n9a %ach PAPI light is like a slide pro6ector with a redbottom segment white top segment" The four lights areset at a different angle! so that when you are on the

correct glideslope you see two reds and two whites"The slope set corresponds with the I7S glideslope angleand will lead you to the radar touchdown point! usually3'''G in" If it isnGt an I7S runway! the PAPIs are set at> degrees"

+hen you are on the slope! the red PAPIs are ne#t tothe runway" That may not seem important! unless youare a CAA e#aminer" I was asked that in my air lawe#am! and couldnGt remember despite haing stared atthem regularly for oer ten yearsR

11th $ebruary 2000,02:59

#3 (permalink )

shakespeare

Posts, n9a The thing to remember with PAPI lights is that theybring you to the same touchdown point" i"e" 4 whitesand 4 reds > degree glide path" > reds and 3 white)flown constantly* reduces the angle but you willtouch down at the same point" The same applies

flying > whites and 3 red! howeer with a higherangle"

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22/22

Kope that helpsR

29th January 2001,

08:06

#8 (permalink )

Ooeman

Posts, n9a Precision Approach Path Indicator )PAPI* was inentedin %ngland "" the name Tony Smith is often associatedwith this inention "" which is probably true ""

PAPI was adopted by the International Ciil Aiation:rgani$ation )ICA:* and was to replace the olderG>'H """ the units ? and C define theHapproach corridorH with which the approach path

)slope* is )?MC*94>G''H """ pilots fly the HapproachcorridorH )two whites and two reds* and not theapproach path since the path itself is not seen """

the PAPI signal is not coincident with the I7S path """ itcan only be made to be appro#imately close to the I7Spath through increasing the width of the approachcorridor which is indicated by the color signals """ thePAPI is a isual aid

information on PAPI is aailable in the ICA: Anne# 3;!/AA adisory circulars and Transport Canada manual

TP>34 """ as well as in the pilot flight manuals """
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TCAS Philosophies

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