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Co nsFMSNews e er

Business and Regional SystemsJuly 1998

Volume 1, Issue 2

LANKS

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Introduction

The Collins FMS Newsletter updatesour FMS customers with developmentsregarding our Collins FMS products. Thisissue includes certification news, aFeature Priority Poll and an introductionto the FMS Training Department. Alsoincluded is an overview on how the FMSdetermines position using multiple

sensors as well as the first in a series ofARINC 424 leg type descriptions.

Distribution

This newsletter is published quarterly(January, April, July and October) andmailed to all operators included on theCollins FMS Newslettermailing list. To beadded to our mailing list, fax your name,organization, mailing address and phone

and fax numbers to the attention of ToddTwachtmann at (319) 295-2530.

New Certifications

Collins continues to certify FMSsystems. Below are some of our mostrecent certifications.

AIRCRAFT SYSTEM HIGHLIGHTS

Falcon 20 FMS-6000 InitialCollins FMSCertification

Falcon 2000 FMS-6000 InitialCollins FMSCertification

Feature Priority Poll

Attached is a Feature Priority Poll,which each operator is encouraged tocomplete and return via mail or fax. Thefeatures listed are a collection gatheredfrom previous operator inputs. If youhave additional suggestions, please notethem on the Feature Priority Poll.

Prioritize the features using one oftwo methods. You may mark them insequential order with one as the mostdesired feature, two as the second mostdesired feature, etc. Another method isto rank the features in categories of tenwith the ten most highly desired featuresconsidered as high priority, the secondgroup of ten considered as a mediumpriority and the remaining features con-sidered as low priority.

Collins FMS Training Support

The Customer Service Training De-partment is pleased to be included in theFMS Newsletter. We look forward topresenting FMS operational tips andsolutions to your training needs.

Who are we? We are a part of theRockwell Collins, Business and RegionalSystems, Customer Service Department.We provide worldwide training support

not only on pilot issues but also on flightline maintenance topics. Our primaryfunction is to train the trainer. In otherwords, we support the training vendorsthat you routinely use such as FlightSafety International, Bombardier andSimuflite. We also support the trainingdepartments of many regional airlines.

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For customers who want in-depth systemknowledge, we have the capability toprovide crew training in Cedar Rapids.

By far the biggest benefit we canoffer is our ability to provide highly

qualified and experienced training pilotsto answer your operational questions.Jim Wright leads the pilot training and isbacked up by Gerry Zanardelli and BobBrown. When you have questions giveJim a call at (319) 295-8573. If hedoesnt answer, please leave a messageon his voice mail or, if youre equipped,his e-mail address is

jwright@collins.rockwell.com. You mayfax information to Jim at (319) 295-1542.Hell answer your questions as quickly aspossible.

It is our intent to contribute a series ofoperating tipsto this publication. Many ofthese tips are procedures that you, thecustomer, have contributed. If you arewondering about an issue, someone elseis also probably curious about the samething. In fact, your question may besomething we think everyone shouldknow about. So let us know your

questions, dont keep them a secret.

nn Did You Know? In order to reduce distraction,

yellow FMS messages are notdisplayed for two minutes duringtakeoff and climb-out. The clockstarts at 60 knots. However, it isimportant to note that only the non-criticalFMS messages are inhibited.

Yellow warnings critical to flightsafety are alwaysdisplayed.

nn Passed or Edited Waypoints Are

Retrievable From the History Pages Pressing the DIR key, then the

PREV key will show the last 15waypoints either passed or edited

out of the flight plan. Pressing theline key beside a waypoint will loadit as the TO waypoint along with thesubsequent waypoints from thehistory pages. This is a quickmethod to return to a previous

non-approach waypoint. However,remember to check the waypointlineup on the leg page beforeexecuting, since history pages arebuilt in the order that the waypointswere either passed or deleted andthat may not be the order you nowwant them.

Never reload an approach fromthe history pages.

Again, the sequence and altitudemay not be correct. It is alwaysbestto load an approach from thedeparture/arrival menu page.

Customer Input

As stated in the April edition,operators are encouraged to providefeedback regarding operational sugges-tions or future newsletter topics. To

ensure proper transmission andinterpretation of operator input, pleasesend written suggestions to the attentionof Todd Twachtmann at:Fax (319) 295-2530E-mailtatwacht@Collins.Rockwell.com

Coming Next Edition

In upcoming newsletters, Rockwell

Collins will provide details anddescriptions of the various ARINC 424leg types used to code FMS procedures.Although not fully understood byeveryone, knowledge of leg typesfrequently provides insight into howJeppesen uses the various leg types tobreak down procedures into data useablefor the FMS to-flyprocedures.

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OVERVIEWHow the FMS Determines Position Minus all the Math___________

An often-asked question from Collins

FMS users is How is the FMS positiondetermined? Variations of the questioninclude:

n How is IRS used?n How does the FMS navigate?n How heavily is GPS weighted in

position determination?

The Simple Answer

Like many things, the simple answeris It depends! Since most people findsuch an answer less than satisfying, thisdocument will provide an overview intothe concepts of FMS positiondetermination.

Blended Solution

Normally, the FMS uses all installedand available navigation sensors (GPS,DME / DME, VOR / DME and IRS) to

determine position. Each sensorsposition is independently calculated, thenthe individual positions are blended tocreate the FMS position. The FMSPOSITION SUMMARY page on the MFDprovides a bearing / distance differencebetween the blended (FMS) position andeach sensor capable of calculating aposition independently.

In areas of the world whereVOR / DME and DME / DME coverage is

adequate, both are good solutions. Ifinstalled, GPS provides a good solution.

Reasonableness Check

Each sensor is evaluated forreasonableness. For example, the FMS

selects VOR and DME navaids based on

the FMS-calculated present position, theaircrafts distance from each station,each selected navaids service volume(that is the area within which the navaidhas been flight-checked to be accurate)and the geometry of navaids that will givethe best possible solution. Afterautomatically tuning a DME, the FMSchecks the identifier. If the identifier doesnot match the intended identifier, thenthe navaid is no longer used. The FMSthen compares the actual station data(bearing for VOR, distance for DME) withthe predicted station data. If a substantialdifference exists, the station is not used.

Sensor Weighting in the Solution

In general, if GPS is installed andavailable, it is more heavily weightedthan other sensors in the positionsolution. GPS is more heavily used if theGPS Probable Error is small, and is less

heavily used as the Probable Errorincreases. The technical term for GPSProbable Error is Horizontal Figure ofMerit (HFOM). It is an indication of thegoodness of the GPS satellite geometry.For GPS to be used, the integrity of thedata must also be monitored by means ofthe GPS-calculated HIL (HorizontalIntegrity Limit) value. GPS HIL is an in-dication (in nautical miles) of the errorthat the GPS can guarantee will not beexceeded without annunciation.

DME / DME usage in the positionsolution depends on geometry andreasonableness (as described in theprevious section). The FMS uses datafrom DME stations that are separated bymore than a 25 angle. In the example inFigure 1, of the five navaids shown, thefollowing would be used (if all werewithin their service volume, received and

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reasonable): either VOR / DME 1 orVOR / DME 2 (but not both), DME 3 andeither VOR / DME 4 or VOR / DME 5 (butnot both).

VOR / DME is used to a lesserdegree (it is de-weighted) as the distancefrom the station increases. Remember, aone-degree change in a VOR bearingequals one Nautical Mile (NM) change at

60 NM from the station. VOR / DME isremoved from the solution when thenavaid is outside its service volume orwhen the aircraft is overhead the station.

Normally IRS is not used in FMSposition solution. Instead, the differenceor biasbetween each IRS and the FMS isconstantly computed. (This is the resultof the IRS drift.) In the event that allsensors except IRS are not available, theFMS then applies each IRS bias to eachIRS position and uses the result as theIRS position. With time, it is assumed theIRS position will drift.

When the FMS is using only IRS, nochange to the bias is calculated, since nocomparison source exists.

Although this newsletter does notserve as a detailed operationaldescription, it is intended to giveadditional insight into the determinationof FMS position. Please contact the FMSProduct Support group for additionalinformation on this subject.

OVERVIEWFMS Leg Types __________________________________________

Summary

Flight Management Systems utilize aset of industry standard leg type to-flyprocedures such as SIDs, STARs andapproaches. These leg types have a

direct effect on the path the aircraft takesthrough space, even though these legtypes are not specifically visible to theaircraft operator.

Detail

In the early days of FlightManagement Systems, it was relativelyeasy enter the waypoints and the

system would fly from point to point. Ifyou had an advanced system, it wouldeven anticipate the turn onto thesubsequent leg so as to roll the aircraft

precisely on the new track with noovershoot. Flight Management Systemstoday do all that and much more.

As the air traffic environment becameincreasingly complex, a method wasneeded to communicate the intent ofcomplex procedures to a computer (theFMS) which is capable of only digital (yesor no) decisions.

Figure 1

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Out of this need to communicate withthe FMS, a set of industry standard legtypes was developed. ARINC Spec-ification 424 is the document that defines

the format and content of NavigationDatabases. Attachment 5 to ARINC 424defines the Path and TerminatorConcept. This concept was developed asa means to permit coding of TerminalArea Procedures, SIDs, STARs andApproach Procedures, withoutproliferating the number of namedwaypoints required to support suchprocedures. (Quoted from ARINC 424-13, Attachment 5, page 142.)

Simply put, the Path and TerminatorConceptdefines every leg of a procedureas having a termination point and somekind of path into that termination point.

Paths

As mentioned above, each leg typehas some associated path (well, ok,almost every leg type more on that inthe next issue). These path definitions

take two basic forms: a fixedpath acrossthe ground (such as a course or track) ora floatingpath (such as a heading).

Terminators

Every leg has some type of termina-tion point. Leg termination points (orterminators) fall into two distinctcategories.

The first category is the namedwaypoint terminator, which represents ageographic location that has a definedname in the database. These namedwaypoints may be entered into the FMSvia the CDU keyboard and recalled fromthe Navigation Database. Named way-point terminators appear on the MFDmap as a four-pointed waypoint symbol.

The second leg terminator category isthe conditional waypoint. As the nameindicates, the leg terminates when aspecified condition is met. Reaching a

specified altitude or DME distance, cross-ing a VOR radial or intercepting the nextleg of the flight plan are typical conditionsthat define a conditional leg terminator.Conditional waypoint terminators appearas small circles on the MFD map.

Leg RepresentationCDU and MFD

The ARINC 424 two-letter leg type

abbreviations and plain English descrip-tions of these leg types are listed on thefollowing page. The figures that followrepresent the intent of the leg type andare not necessarily the exact graphicalformat displayed on the MFD.

Further Reading

For those who desire to dig deeperinto the world of leg types, Attachment 5

to the ARINC 424 Specification has morethan 50 pages of rules associated withthe various leg types. The current versionof ARINC 424 is the 13version. The 14version is in draft form. Future issues willdiscuss each leg type individually infurther detail.

Named Waypoint Conditional Waypoint

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ARINC 424 TWO-LETTERLEG TYPE ABBREVIATIONS AND DESCRIPTIONS

424 Description CDU LegsPage

Example

IF Initial Fix ICTTF Track to a Fix CID

045

DBQ

CF Course to a Fix {L or R}110SWISH

DF Direct to a Fix {L or R}(DIR)ELEYS

AF Arc to a Fix 10 ARC RD090J

RF Radius to a Fix {Future}

CA Course to an Altitude 045

(5000)CD Course to a DME Distance 085

VNY/02

CR Course to a VOR Radial 225SEA225

CI Course to Intercept (the next leg) 090(INTC)

FA Course from a Fix to an Altitude 070(3300)

FD Course from a Fix to a DME Distance 085DDY/26

FC Course from a Fix to an Along Track Distance 090

FIM090FM Course from a Fix to a Manual Termination 110

(VECT)

VA Heading (Vectors) to an Altitude 070H(4500)

VD Heading (Vectors) to a DME Distance 085HSSN/05

VR Heading (Vectors) to a VOR Radial 070HSMO225

VI Heading (Vectors) to Intercept (the next leg) 090H(INTC)

VM Heading (Vectors) to a Manual Termination 110H

(VECT)PI Procedure Turn P-TURN

(INTC)

HF Hold at a Fix HOLD AT CID

HA Hold at a Fix to an Altitude HOLD ATCID 5000

HM Hold at a Fix to a Manual Termination HOLD ATCID

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Initial Fix Track to a Fix Course to a Fix

Direct to a Fix Radius to a Fix

Course to an Altitude Course to a DMEDistance Course to a VOR Radial

Course to Intercept Course from a Fix to an Altitude

Course from a Fix to anAlong Track Distance

Course from a Fix to aManual Termination Heading to an Altitude

Heading to a DME Distance Heading to a VOR Radial Heading to Intercept

Heading to a Manual Termination Procedure Turn Hold at a Fix

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FOR MORE INFORMATION

contact

Rockwell Collins

400 Collins Road N.E.

Cedar Rapids, Iowa

52498

Phone (319) 295 4085

www.collins.rockwell.com

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