aero q209 article05

7/28/2019 AERO Q209 Article05

1/9AERO quARTER Ly qT R_02 | 0

Flght management

sstems have evolv

a level o sophstca

that helps fght crew

commercal arplane

more sael and ec


2/9WWW.BOEiNG.COM/COMMERCiAL/AEROMAGAziNE

Contrbton o

Flght Sstems toPerormance-BasedNavgaton

B s mller,Assocate Techncal Fellow, Flght Deck, Flght Crew Operatons

Flght Management Sstems (FMS) and assocated arplane fght sstems are the

prmar navgaton tools on board todas commercal arplanes. The evolton o these

sstems has led the wa or perormance-based navgaton (PBN) and the u.S. Federal

Avaton Admnstratons (FAA) Next Generaton Ar Transportaton Sstem.

PBN s a concept sed to descrbe navga-

ton perormance along a rote, procedre,

or arspace wthn the bonds o whch

the arplane mst operate. For transport

arplanes, t tpcall s speced n terms

o rered navgaton perormance (RNP).

The PBN concept denes navgatonperormance n terms o accrac, ntegrt,

avalablt, contnt, and nctonalt.

These operatons provde a bass or

desgnng and mplementng atomated

fght paths that wll acltate arspace desgn,

termnal area procedre desgn, trac fow

capact, and mproved access to rnwas

(more normaton abot PBN can be ond

nAERO second-arter 2008). The PBN

concept s made possble largel b

advances n the capabltes o arplane FMS.

Ths artcle helps operators better

nderstand how the FMS and other

arplane fght sstems have evolved over

tme, how the contrbte to PBN opera-

tons, and plans or rther advancement.

aiR naviGaTiOn TOOLs LEaDi nG UP

TO THE Fms

Earl avators reled on ver basc nstr-

mentaton to keep the arplane prght and

navgatng toward the desred destnaton.

Earl trn and slp ndcators and grond

reerences sch as lghted beacons enabled

avators to f coast to coast across the

unted States. However, these earl fghts

were lled wth ncertantes and ther se

o vsal fght rles soon gave wa to

relable atttde ndcators and grond-

based navgaton ads, or navads. Non-

drectonal rado beacons and the arplanesarborne atomatc drecton nder ep-

ment allowed avators to home n on the

beacon and navgate relabl rom staton to

staton. Non-drectonal rado beacons are

stll beng sed toda throghot the world

in the 1940s, the ntrodcton o a

rado-magnetc ndcator or dal-bearng

dstance-headng ndcator acltated the

se o grond-based navads, ncldng



the ver-hgh-reenc omn-drectonal

range (VOR) navgaton sstem and ds-

tance measrng epment (DME). VORs

came nto wde se n the 1950s andckl became the preerred navgaton

rado ad or fng arwas and nstrment

approaches (see g. 1). VOR and DME

provded the ramework or a permanent

network o low-alttde vctor arwas

(e.g., V-4) and hgh-alttde jet rotes

(e.g., J-2), whch are stll n place toda.

Long-range navgaton over remote

and oceanc areas, where navgaton rado

transmtters dd not exst, was orgnall

accomplshed b dead reckonng and

celestal navgaton. The ntrodcton o thenertal navgaton sstem (iNS) on arplanes

acltated long-range capablt b provdng

a contnos calclaton and dspla o the

arplanes poston. Flght crews cold enter

waponts and the iNS wold calclate

headng, dstance, and estmated tme o

arrval to the respectve wapont.

At the same tme, the 1970s el crss

provded the drve to optme navgaton

capabltes n commercal arplanes. As

a reslt, avoncs manactrers began

prodcng perormance management

compters and navgaton compters to

help operators mprove the ecenc o

ther arlne operatons. Boengs ntal entr

nto ths arena was represented b the

mplementaton o the earl Sperr (now

Honewell) atomatc navgaton sstems

on the 727, 707, and 747-100. Drng ths

same tme, Collns prodced the AiNS-70,

an area navgaton (RNAV) compter on the

DC-10. Each o these steps redced theamont o nterpretaton b the fght crew

b presentng more specc ndcatons o

arplane postonal and statonal stats.

Even so, the relance on the fght crew to

manall nterpret and ntegrate fght

normaton stll provded opportntes or

operatonal errors.

THE FiRsT inTEGRaTED FLiGHT

manaGEmEnT COmPUTER

When Boeng began work on the 767

arplane program n the late 1970s, the

compan created a fght deck technolog

grop wth engneers dedcated to the

development o the fght management

compter (FMC) and the control dspla

nt (CDu) (see g. 2). Boeng merged

prevos desgns o the perormance

management compter and the navgaton

compter nto a sngle FMC that ntegrated

man nctons beond navgaton and

perormance operatons. The compansed experence ganed rom Boengs other

research projects to develop advanced

mplementatons o perormance manage-

ment nctons and navgaton nto a

sngle FMC. The new FMC sstem was

envsoned as the heart o an arplanes

fght plannng and navgaton ncton.

Whle Boeng was contnng work on

new commercal arplane navgaton sstem

or the new glass fght decks, a debate

was nder wa among the arlnes abotthe need or a dedcated fght engneer

crewmember. in Jl 1981, an ndstr tas

orce determned that two-crew operaton

was no less sae than three-crew operaton

Ths decson wold have a proond eect

on the desgn o all Boeng commercal

arplanes, ncldng a short-notce mple-

mentaton or the new 767. Wth one ewer

crewmember, Boeng engneers ocsed o

a fght deck desgn that wold redce crew

workload, smpl older plotng nctons,

and enhance fght deck ecences.The earl 767 FMC provded arplane

perormance predctons sng stored

arrame/engne data and real-tme npts

rom other onboard sstems, sch as the

ar data compter and nertal reerence

sstem (iRS). Ths perormance ncton

replaced fght crew back-o-the-envelope-

tpe estmates wth relatvel precse tme

and el predctons based pon actal

arplane perormance parameters, sch as

gross weght, speed, alttde, temperatre

and wnds.

Then, as now, the navgaton ncton

was based on the iRS poston and sed

grond-based navads (e.g., DMEs, VORs,

localers) to rene the iRS poston and

correct or iRS drt. A navgaton database

(NDB) was nclded n the FMCs memor

Fgure 1: Tpcl vOR tllto

B 1952, more than 45,000 mles o arwas sng

the VOR were n operaton. A DME transmtter

was sall located on the grond wth VOR

statons. DME transmtters wold respond to

nterrogaton b transcever epment nstalled on

arplanes and provde the plot wth a relable

dstance n natcal mles to the transmtter. Plots

operatng n areas where VOR and DME coverage

was avalable had both dstance and corse

normaton readl avalable.270-degree Radal

270

180

360

90

15 DME

VOR/DME



Fgure 2: 757/767 FmC CDU

One o the rst mplementatons o an FMC

CDu was desgned or the 757 and 767

n the earl 1980s.

and contaned approxmatel 100 klobtes

o data consstng o navads, arwas,

approach procedres, and arports. The

NDB allowed fght crews to easl enterfght plans rom takeo to landng and

make real-tme rote changes n response

to ar trac control (ATC) clearances. The

FMC also provded gdance to the fght

plan rote sng the lateral navgaton (LNAV)

and vertcal navgaton (VNAV) nctons.

intall, the FMC was epped wth LNAV

onl. VNAV was a new challenge and

rered a sgncant eort on the part

o Boeng and Sperr (now Honewell)

engneers to make the vertcal gdance

component operatonal.Ater the development o the 757 and

767, Boeng also worked wth Smths

Aerospace (now GE Avaton) to develop

an FMC as part o a major pdate to the

737 aml. The operaton o the 737 FMC,

the appearance o the CDu, and the CDu

men strctre were desgned to parallel

those on the 757 and 767. The FMC

became part o the desgn o the 737

Classc aml, whch nclded the 737-300,

737-400, and 737-500. The 737-300 was

the rst o the aml to be certed n 1984.

Boeng oered the 737 Classc aml wth

ether sngle or dal FMCs and wth ether

the tradtonal electro-mechancal atttde

drector ndcator/horontal staton

ndcaton fght nstrment ste or the

EADi/EHSi glass fght deck derved

rom the 757/767 desgn.

For several ears ollowng the ntal

FMS certcatons, mnor changes were

made to enhance the FMS operaton,

bt no sgncant hardware or sotwarechanges were made ntl the earl 1990s.

DEvELOPinG THE mODERn FmC

in the late 1980s and 1990s, the arlne

ndstr reested the capablt o drect

rotng rom one locaton to another,

wthot the need to ollow arwas based

pon grond-based navads. Modern

FMS epped wth a mlt-sensor nav-

gaton algorthm or arplane postondetermnaton sng VOR, DME, localer,

and iRS data made ths possble, and

RNAV was transormed rom concept to

operatonal realt.

Bt oceanc operatons and fght

over remote areas where mlt-sensor

pdatng o the FMC cold not occr

wth accrac better than the drt o iRS

sstems made RNAV operatons dclt.

Operatons n these areas o the world were

ncreasng drng the 1990s, and there was

pressre on avoncs spplers, arplanemanactrers, and reglator agences

to nd a wa to spport precse navgaton

n remote and oceanc areas. As a reslt,

the concept o a tre ar navgaton

sstem (FANS) was conceved n the earl

1990s (seeAERO second-arter 1998).

Sbseentl, Boeng and Honewell

ntrodced the rst FANS 1-capable FMC



on the 747-400. At the heart o the sstem

was a new, more capable FMC that

mplemented several new operatons:

n Arlne operatonal commncatons

Dgtal commncaton o data (data lnk)

sch as fght plans, weather data, and

text messagng drectl rom the arlne

operatons aclt to the FMC.n Controller-plot data lnk commnca-

tons Dgtal commncaton between

ATC and the arplane n the orm o

predened messages.n Atomatc dependent srvellance

inormaton abot poston and ntent

generated rom an ATC reest.n Global postonng sstem (GPS)

incorporaton o satellte navgaton

nctons n the FMS or the prmar

means o navgaton.n Ar trac servces acltes notcaton

ATC commncaton protocol ntalaton.n RNP A statement o the navgaton

perormance necessar or operaton

wthn a dened arspace.n Rered tme o arrval Enablement o

arplane perormance adjstments to

meet speced waponts at set tmes,when possble.

Althogh each eatre was ndvdall

sgncant, the three prmar enablers or

FANS operatons were RNP, GPS, and data

lnk. RNP dened the connes o the lateral

rote, and the FMC provded gdance to

relabl reman on the rote centerlne. The

FMCs RNP ncton also provded alertng

to the fght crew when ths contanment

mght not be assred. GPS was orgnall

a mltar navgaton sensor that was

allowed or commercal se wth somelmtatons. integrated as the prmar FMC

poston pdate sensor, GPS provded

exceptonall precse poston accrac

compared to grond-based sensors and

enabled the FMCs capablt or precse

navgaton and path trackng. GPS remans

the prmar sensor or the crrent gener-

aton FMCs. Data lnk provded a relable

method o dgtal commncaton between

the arplane and the ar trac controller.

A comprehensve lst o preormatted

messages was mplemented to provde orecent trac separaton reerred to as

controller-plot data lnk commncatons.

Concrrent wth the FANS 1 FMC,

Alaska Arlnes teamed wth Boeng, Smths

Aerospace (now GE Avaton), and the

FAA to develop procedres that wold

provde relable access to arports that

are srronded b dclt terran. B

vrte o the srrondng rogh terran,

the Jnea, Alaska, arport became the

prme canddate or the certcaton eort.

Becase the approach to rnwa (RW) 26

was the most challengng ar corrdor to

Jnea, t was selected as the most

rgoros test to prove the real perormance

capablt o RNP (see g. 3).

in 1995, Alaska Arlnes sccessll

demonstrated ts ablt to sael f arplanes

to RW 26 sng RNP and soon began

commercal operatons sng RNP, whch

was a rst or commercal avaton.

RnP: EnaBLER OF PBn

The concept o a relable and repeatable

dened path wth contanment lmtswas not new. Earl conceptal work was

done at the Massachsetts insttte o

Technolog n the 1970s, bt the modern

FMC, wth ts poston accrac and

gdance algorthms, made relable path

mantenance practcal.

The rst demonstraton o the FMCs

termnal area precson came at Eagle,

Colorado, n the md-1980s. A team com-

prsng Amercan Arlnes, the FAA, and

Sperr (now Honewell) appled RNP-lke

prncples to approach and departreprocedres to the terran-challenged

rnwa. Followng smlator trals, the

procedres were sccessll fown nto

Eagle and sbseentl approved b the

FAA. The reslt: relable approach and

departre procedres that provde mprove

access to Eagle.

Althogh Eagle demonstrated the FMC

capablt to execte precsel desgned

termnal area procedres, n the md-1980

t wold take another 10 ears ntl RNP

epment was avalable or arlne oper-

ators. The FMCs navgaton poston

accrac enhanced wth GPS and lateral

and vertcal gdance algorthms, the

development o the vertcal error bdget,

and addtons to crew alertng enabled

RNP and ts tre applcatons.

RNP s a statement o the navgaton

perormance necessar or operaton wth

An RNP sstem shold contan both perormance

montorng and alertng: a caton alert s ntated b theFMC and annncated on the dspla sstem to drawfght crew attenton n the event that ANP exceeds RNP.



a dened arspace. The FMCs navgaton

ncton ensres contanment wthn the

dened arspace b contnosl comptng

the arplanes poston. The FMCs actalnavgaton perormance (ANP) s the com-

pted navgaton sstem accrac, pls the

assocated ntegrt or the crrent FMC

poston. it s expressed n terms o natcal

mles and represents a rads o a crcle

centered on the compted FMC poston,

where the probablt o the arplane

contnosl beng nsde the crcle s

95 percent per fght hor.

Boeng fght decks dspla both ANP

and RNP. Wth the advent o the navgaton

perormance scales (NPS) and assocateddspla eatres, RNP and ANP are

dgtall dsplaed on the navgaton dspla.

Addtonall, and as dened n reglator

gdance, an RNP sstem shold contan

both perormance montorng and alertng:

a caton alert s ntated b the FMC and

annncated on the dspla sstem to draw

fght crew attenton n the event that ANP

exceeds RNP. That alert tpcall sgnes

that the perormance o an FMC poston

pdate sensor has deterorated, and,

sbseentl, the compted navgaton

sstem accrac can no longer ensre

contanment (see g. 4).

The FMCs LNAV ncton contnall

provdes gdance to mantan the lateral

path centerlne and an devaton rom

the path centerlne s dsplaed as lateral

cross-track error. in Boeng arplanes, cross-

track error s dsplaed on the FMCs

PROGRESS page or nder the navga-

tonal dsplas arplane smbol when NPS

s on board. The dspla provdes fghtcrews wth a precse assessment o lateral

devaton, partclarl mportant n low

RNP envronments. Dspla o cross-track

error on the PROGRESS page was an

orgnal eatre n the Boeng FMCs and

contnes as a ndamental ndcaton

o path devaton.

Althogh RNP operatons are ncreasng

n nmbers and applcatons and wll provde

or the tre or PBN, RNAV s also beng

ncreasngl mplemented or operatons

where consstent grond tracks are desred.RNAV approaches, standard nstrment

departres (SiD) and standard termnal

arrval (STAR) procedres are beng

prodced prmarl throghot the unted

States and n selected areas o the world.

RNAV leverages the orgnal path manage-

ment capablt o the FMC and, nlke

RNP, lateral contanment was not speced.

From an operatonal pont o vew, RNP s

RNAV wth contanment. i a path s dened

and actve n the rote, the FMC s desgned

to mantan the centerlne o the path. That

basc operaton has not changed snce the

orgnal 767 FMC.

COnTinUED FmC mODERnizaTiOn

The 737, 747-400, MD-80, and MD-11

FMC nctons that enabled RNP were

reasonabl robst or the ntal RNAV and

RNP operatons, bt each o the Smths

(now GE) and Honewell FMCs on Boeng

arplanes contned to be pdated wthsotware mprovements and new hardware

versons wth enhanced processng power

and memor. Some enhancements

speccall related to RNP nclde:

n Vertcal RNP introdced the capablt

wth whch to dene contanment relatv

to the compted VNAV path (see g 5).n Rads to x legs implemented the

ARiNC 424 leg tpe that provded a xed

rads grond path (smlar to a DME

arc bt wthot the rered navad).n En-rote xed rads transtons

implemented a xed rads transton

between en-rote path segments, to

enable the mplementaton o redced

rote spacng n hgher-denst trac

envronments (crrentl 737 onl).n GPS avalablt Rened algorthms

that enhanced the navgaton peror-

mance or ver low RNP procedres.n LNAV trackng Enhanced the pre-

cson and aggressveness o LNAV

path trackng.n NPS Provded data to the dspla

sstem or lateral and vertcal path

devaton scales, devaton ponters,

and sensor perormance ndcatons.n RNP rom the NDB Enabled appl-

caton o RNP vales coded n the NDB

or rotes and procedres.

Fgure 3: Jueu, alk: ste o tl

RnP certfcto eort

RNP enabled an approach to rnwa 26 and

access to Jnea that n some weather condton

was not otherwse practcal.



As a reslt o these enhancements

and addtons to other FMC nctons, the

modern FMC s well-epped or RNP

operatons that wll enable tre arspace

management concepts.

THE PROmisE OF PBn

PBN, whch comprses both RNAV and

RNP speccatons, provdes the bass or

global standardaton, whch wll acltate

tre arspace desgn, trac fow, and

mproved access to rnwas. Ths change

oers a nmber o operatonal benets,

ncldng enhanced saet, ncreased

ecenc, redced carbon ootprnt,

and redced costs. To ll reale these

benets, operators ma need to make

changes to ther arplanes and operatons.

The prmar premse o a PBN sstem

s to move awa rom restrcted, sensor-based operatons to a perormance-based

navgaton sstem that ncorporates

RNP as the ondaton and a sstem n

whch operatonal cost ecences are

emphased (see g. 5). Accordng to the

internatonal Cvl Avaton Organaton

Perormance-Based Navgaton Manal,

arspace procedres shold be desgned

to redce track mles, avod nose-senstve

areas, and redce emssons throgh

the se o ecent descent paths b

mnmng termnal area maneverng

(.e., nwanted throttle movement) and

perodc alttde constrants.

aiRsPaCE mODERnizaTiOn

The crrent arspace sstem o arwas

and jet rotes has not changed sgncantl

snce the ncepton o non-drectonal

beacons and VORs n the mddle o the

last centr. incremental mprovements,

Fgure 4: RnP prctce

RNP denes the path and allowable tolerance or contnos operaton (+ 1 RNP). Contanment to

ensre obstacle clearance s dened as + 2 x RNP. ANP less than the prescrbed RNP provdes poston

assrance or contned operaton.

ANP contanment rads

RNP and ANPdsplaed onthe FMC CDu

ANP 1 x RNP orcontned operaton

Lateral bondar = 2 x RNP(arspace and obstacle)



Fgure 5: Beeft o PBn

These actal trac plots at a major arport demonstrate the ecences that can be realed when a PBN desgn s mplemented.

Track mles can be sgncantl redced throgh redced vectorng, savng tme, el, and emssons. Addtonall, convectve

weather, restrcted arspace, and nose-senstve areas can be avoded sng ether desgned procedres or dnamc rerotng.


9/9AERO quARTER Ly qT R 02 | 0

sch as RNAV en-rote waponts, RNAV

SiDs and STARs, FANS dnamc rerotng,

and q-rotes, have been mplemented, bt

the general strctre o the arspace stllrefects hstorc ATC methods.

in a drect contrast to the PBN approach,

the ncreased trac snce the earl 1990s

has necesstated more complex arrval and

departre procedres procedres that

reentl nfct a penalt on el ecenc

wth an added conseence o ncreased

potental or fght crew error.

The PBN concept s centered on

operatonal ecences. Several sccesses

have alread been realed. Procedre and

arspace desgners n Canada and Astralahave worked wth operators to plan rotes

and termnal area procedres that redce

track mles whle addressng envronmental

sses that are recevng ncreased scrtn

b the pblc and government. Both

Erope and the unted States are mple-

mentng RNAV and RNP procedres.

FUTURE COnCEPTs

Advanced arspace envronments ncldethe FAAs Next Generaton Ar Transpor-

taton Sstem, whch wll transorm the

crrent grond-based ATC sstem to

satellte-based, and Eropes Sngle

Eropean Sk ATM Research (SESAR).

Mgratng to these envronments wll

rere ndamental changes to ar trac

management methodolog. The arspace

strctre, procedre desgn, and trac

control methodolog wll need to ocs on

saetandecenc capactes are to

ncrease at major arports and operators areable to mantan el costs wthn reason.

Concrrent wth the arspace evolton,

the FMC wll contne to rere enhance-

ments that ether control or partcpate

wth other onboard sstems or new trac

control methods. These methods nclde

tme-based meterng, mergng and spacng,

sel-separaton drng contnos descent

arrvals and/or drng the nal segment,

atomated dependent srvellance

broadcast, and cockpt dspla o trac

normaton. New termnal procedres, schas a hbrd RNP procedre that termnates

n an nstrment landng sstem or a global

navgaton satellte sstem landng sstem

nal and atoland, are alread n the FMCs

repertore. However, consderatons to

the assocated fght mode annncator

changes drng the transton rom FMC-

based gdance to atoplot gdance on

short nal and other crew dstractons wll

rere attenton. The new 787 and 747-8

FMCs are addressng some o these sses

and mplementng enhancements that

poston those models or tre PBN

operatons. Addtonall, each o the FMC

desgns has ncorporated growth optons

so that changes to the FMC can be made

wth mnmal mpact to the FMC sotware.

Flght crews wll see sgncant mprove-

ments n speed, capablt, and operaton

o the 737 FMC and the new FMCs n the

787 and 747-8 arplanes. Althogh modern

n ever respect, each o the FMCs s oper-

atonall smlar to the orgnal 767 FMC

o the earl 1980s. To address sstemcomplext and enhance the operatonal

capablt o the fght crew or the transton

to the Next Generaton Ar Transportaton

Sstem, Boeng and ts partners are

nvestgatng new fght management meth-

odologes that ocs on fght path trajector

management and ease o operaton. Sch

new sstems wll assst the fght crew n

managng the trp costs and contrbte to

a sae conclson to each fght.

sUmmaRy

Flght management sstems have evolved

to a level o sophstcaton that helps fght

crews f commercal arplanes more sael

and ecentl, whle enablng PBN throgh

applcaton o RNP and the evolton to

tre arspace management sstems.

For more normaton, please contact

Sam Mller at [email protected].

Contributors to this article: John Hillier,

chie engineer, Flight Management SystemsCenter o Excellence, Honeywell Aero-

space; Robert Bush, sotware tech lead,

737 Flight Management Computer System

GE Aviation; John C. (Jack) Grifn, associate

technical ellow (retired), Boeing.

aero q209 article05

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