RNAV waypoint meanings and decodes

[skyhigher]

Can anyone explain the procedure for decoding RNAV waypoints on sid, stars and approach charts. I'm aware that some have direct meanings (centre fix etc) but do they all? is there a decode document or format?

[aterpster]

skyhigher:

Can anyone explain the procedure for decoding RNAV waypoints on sid, stars and approach charts. I'm aware that some have direct meanings (centre fix etc) but do they all? is there a decode document or format?

Can you provide a specific example?

[FlyingForFun]

I believe this is country-specific.

In the UK, for example, many points don't have names, but have identifiers which can be decoded.

Typically, the first two letters are the last two letters of the airport's ICAO code. For the intermediate or final approach fix, this is followed by the runway identifier, then the letter I (intermediate), or F. For example, TE26F is the final approach fix for runway 26 at Exeter (EGTE).

The missed approach point, if it coincides with a runway threshold is, typically coded as RWYxx, e.g. RWY26 for runway 26 at Exeter. If it's not at a runway threshold, it is coded as MAxx, e.g. MA02 for runway 02 at Shoreham.

Points on the missed approach are coded such that the first two letters are the last two letters of the ICAO code, this is followed by the letter M, then a number which I believe indicates the order in which the points are flown over. For example, the first (and only) point on the missed approach for runway 26 at Exeter is TEM01.

The plates I'm refering to can be found here for Exeter (http://www.ead.eurocontrol.int/eadbasic/pamslight-4D477DA2CAC19595261E2755BB0750F4/7FE5QZZF3FXUS/EN/Charts/AD/AIRAC/EG_AD_2_EGTE_8-10_en_2010-11-18.pdf) and here for Shoreham (http://www.ead.eurocontrol.int/eadbasic/pamslight-4D477DA2CAC19595261E2755BB0750F4/7FE5QZZF3FXUS/EN/Charts/AD/AIRAC/EG_AD_2_EGKA_8-1_en_2010-01-14.pdf). I'm not 100% sure that what I've quoted can be applied in 100% of cases in the UK, but it's certainly UK-specific. I don't know if other countries employ similar coding or not. Do you need to know any of this to be able to fly the approach? No - you just follow what the plate tells you to do.

FFF
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[ImbracableCrunk]

• RX – runway extension fix
• FA – VFR final approach fix
• CF – final approach course fix
• FF – final approach fix
• IF – initial approach fix
• OM – outer marker
• MM – middle marker
• IM – inner marker
• BM – back course marker
• MD – minimum descent altitude
• A – (+ an alpha) step down fix
• RW – runway threshold
• MA – missed approach point other than RW
• TD – touchdown point inboard of RW.


Alpha suffixes are also DME points. Eg. D095L would be 12DME (L = 12th letter) on the 095 radial.

[FlyingForFun]

ImbracableCrunk,

Interesting list.... do you have a reference?

FFF
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[Capn Bloggs]

D095L would be 12DME (L = 12th letter) on the 095 radial.

Which is very easy to visualise on the "standard" FMS keypad, which is 5 letters across. If your waypoint is D270J, you can easily see that it is at 10 DME, as J is at the end of the second row of buttons.

PS: Not applicable to the nerds who fly A380s with their QWERTY keyboards. :}

[ImbracableCrunk]

Interesting list.... do you have a reference?

FFF
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It's from Boeing's FCOM. The section is from FMS Operation - LNAV - Waypoints.

[FlyingForFun]

Thanks!:ok:

FFF
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[capt. solipsist]

To expand Imbracable's list:


Path Terminators
RNAV Procedure Coding


Arc to a Fix AF
Course to an Altitude CA
Course to a DME Distance CD
Course to a Fix CF
Course to an Intercept CI
Course to a Radial Termination CR
Direct to a Fix DF
Fix to an Altitude FA
From a Fix for a Distance FC
From a Fix to a DME Distance FD
From a Fix to a Manual Termination FM
Racetrack Course Reversal (Alt Term) HA
Racetrack (Single Circuit - Fix Term) HF
Racetrack (Manual Termination) HM
Initial Fix IF
Track to a Fix TF
Procedure Turn PI
Constant Radius Arc RF
Heading to an Altitude VA
Heading to a DME Distance VD
Heading to an Intercept VI
Heading to a Manual Termination VM
Heading to a Radial Termination VR
Initial Fix IF
Track to a Fix TF
Procedure Turn PI
Constant Radius Arc RF
Heading to an Altitude VA
Heading to a DME Distance VD
Heading to an Intercept VI
Heading to a Manual Termination VM
Heading to a Radial Termination VR

[standardset]

Skyhigher,
Try a google search for the above reference. There are several sites that have free Powerpoint, slightly outdated details of the Arinc 424. The definitions in it do not change. Arinc will provide the latest for $250. If you don't have any luck PM me and I will send a link I used in the past.
Standardset

[Upper Air]

. . .so MH28F . . . ?