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Driver170

Approach abbreviations

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Found these and recently i came across CF and FF during the app, can someone highlight the difference between them with CI and FI ? I have used both on ILS approaches. Because i seen no difference in using these two types of abbrevaitions, maybe someone with good experience can help...

 

CD-Course to DME Arc

CF-Course to Fix

CI-Course to Intercept

DF-Direct to Fix

FC-Course from Fix

FD -Fix to DME Arc


Vernon Howells

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CF and FF are part of the name for approach fixes.You'll see those in the FMC on some approaches.

 

I'm not sure what your list is. Is that from how approaches are constructed in the database?


Matt Cee

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Some of the ARINC leg definitions are:

 

IF - Initial Fix or IF Leg. Defines a database fix as a point in space.

 

TF - Track to a Fix or TF Leg. Defines a great circle track over ground between two known databases fixes.

 

CF - Course to a Fix or CF Leg. Defines a specified course to a specific database fix.

 

DF - Direct to a Fix or DF Leg. Defines an unspecified track starting from an

undefined position to a specific database fix. Note See also Table 1.3, Leg Sequencing, for other uses of the DF Leg.

 

FA - Fix to an Altitude or FA Leg. Defines a specified track over ground from a database fix to a specified altitude at an unspecified position

 

FC - Track from a Fix for a Distance or FC Leg. Defines a specified track over ground from a database fix for a specific distance.

 

FD - Track from a Fix to a DME Distance or FD Leg. Defines a specified track over ground from a database fix to a specific DME Distance which is from a specific database DME Navaid.

 

FM - From a Fix to a Manual termination or FM Leg. Defines a specified track over ground from a database fix until Manual termination of the leg.

 

CA - Course to an Altitude or CA Leg. Defines a specified course to a specific altitude at an unspecified position.

 

CD - Course to a DME Distance or CD Leg. Defines a specified course to a specific DME Distance which is from a specific database DME Navaid.

 

CI - Course to an Intercept or CI Leg. Defines a specified course to intercept a subsequent leg.

 

CR - Course to a Radial termination or CR Leg. Defines a course to a specified Radial from a specific database VOR Navaid.

 

RF - Constant Radius Arc or RF Leg. Defines a constant radius turn between two database fixes, lines tangent to the arc and a center fix.

 

AF - Arc to a Fix or AF Leg. Defines a track over ground at specified constant distance from a database DME Navaid.

 

VA - Heading to an Altitude termination or VA Leg. Defines a specified heading to a specific Altitude termination at an unspecified position

 

VD - Heading to a DME Distance termination or VD Leg. Defines a specified heading terminating at a specified DME Distance from a specific database DME Navaid.

 

VI - Heading to an Intercept or VI Leg. Defines a specified heading to intercept the subsequent leg at an unspecified position.

 

VM - Heading to a Manual termination or VM Leg. Defines a specified heading until a Manual termination.

 

VR - Heading to a Radial termination or VR Leg. Defines a specified heading to a specified radial from a specific database VOR Navaid.

 

 

There may be further ones.


Gerry Howard

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I have came across CF FF and CI FI in my navigraph database held in the FMC.

 

I'm just curious in the difference as i have seen both during different ILS app, as to why they are like this?


Vernon Howells

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I understand that the wayoint codes depend on procedure route type

 

FI - Final Approach Fix ILS(I)

FF - Final Approach Fix ILS(L)

FB - Final Approach Fix ILS(B)

FV - Final Approach Fix VOR(V)

FN - Final Approach Fix NDB(N)

FF - Final Approach Fix ILS(L)

FM - Ffinal Approach Fix ML(M)

 


Gerry Howard

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I just can't find the answer why at EGLC rwy 27 they use CF AND FF and all other app are CI AND FI


Vernon Howells

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Perhaps it's because FF is for an ILS(L) procedure but FI is for an ILS(I) procedure ?


Gerry Howard

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Well, if you fly ILS approach why does the FMS coding even matter? It's not like you're shooting it with LNAV.


[color=#a9a9a9][size=1][size=4][img]http://forum.avsim.net/public/style_images/flags/rs.png[/img][/size] Lj. Prodanovic[/size][/color]

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I don't why is it? maybe its part of the procedure turn and thats an requirement? just speculating


Vernon Howells

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 It clearly states what Fx  is - it's a  Final Approach Fix - when there are more procedures for a runway:

 

I = ILS approach

L = Localiser only approach

B = LLZ back course approach


Gerry Howard

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I just can't find the answer why at EGLC rwy 27 they use CF AND FF and all other app are CI AND FI

 

Simple:

One is a course to hit an explicit fix.  The others are courses to intercept another course, or line.

 

The difference in instruction can be metaphorically explained like this:

Case 1:  "Airline 123, proceed direct MOSBY.  Cleared ILS Runway 1R approach."

Case 2:  "Airline 123, fly heading 040 to intercept the localizer.  Cleared ILS Runway 1R approach."

 

Which one is which?

Case 1 is an instruction to fly a course to a fix, so it is CF; Case 2 is an instruction to fly a course until intercepting another course, so it is CI.

 

EDIT:

FWIW, this is pretty obscure, and isn't something you'd be called upon to know at all in being a pilot.  If it helps you understand what the plane is doing, then great, but don't waste your time trying to pick it apart unless you're trying to design approaches on your own.


Kyle Rodgers

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Yeh i see. What about FI? I just can't get my head around why they use different names because either way your going to be intercepting these anyway.

Found this it explains it on pprune, because london city EGLC only has 1 app and that is an ILS

 

 

 

VORDME approach:

 

CD

FD

MD

 

VOR only approach:

 

CV

FV

MV

 

NDB only approach:

 

CQ

FQ

MQ

 

ILS approach:

 

CI

FI

MI

 

generic approach (where there is only 1 approach)

 

CF

FF

MF


Vernon Howells

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I just can't get my head around why they use different names because either way your going to be intercepting these anyway.

 

It's for their own internal purposes, mostly.  They're made up values for cases in which the location in space is not named.  Let it go, honestly.  It carries no purpose at all for the pilot.  Verify the named fixes match.  Let the rest go.


Kyle Rodgers

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Yeh i see. What about FI? I just can't get my head around why they use different names because either way your going to be intercepting these anyway.

 

But you are not going to  be intercepting the same Final Approaches Fixes. There are different ones for  same runway for  different approach procedures.


Gerry Howard

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