I have been trying to relate the LEGS data displayed on the CDU to the various SID, STAR and ILS charts with (in the main) a fair degree of success. However I have been unable to locate a number of FMS LEG names (not sure of the right term here?) on the associated flight chart. In some cases I can fairly confidently guess the location on the chart but cannot work out how the LEG name is constructed.

 

For example: Between DET and DAGGA there is a LEG called D015E that relates to a point on the associated SID chart called "D5 DET" (at 6000 feet). Why is the LEG called D015E on the FMC? Could it mean "Distance 15 nautical miles East of DET"?

 

My main question is: Whilst in the above example I could work out the chart location using a bit of simple deduction, in some cases I cannot find any associated (named) point on the SID, STAR or ILS charts to match a LEG named in the FMC route. Is this "just the way it is" or am I missing something?

 

Bruce

"D5 DET" (at 6000 feet). Why is the LEG called D015E on the FMC?

 

015* from DET and E miles away. E is a fifth letter in the alphabet, so we get 5nm.

This should be described in navigation section in FCOM vol2.

Thanks that's really helpful - I'll go check it out straight away.

 

Bruce

To help you:

 

Boeing 737NG FCOm Vol2 page 11.31.16

 

Procedure Arc Fix Waypoint Names

Unnamed terminal area fixes along a DME arc procedure – unnamed fixes along
a DME arc procedure are identified withthe first character D. Characters 2
through 4 indicate the radial on which the fix lies. The last character indicates the
arc radius. The radius is expressed by a letter of the alphabet where A = 1 mile, B
= 2 miles, C = 3 miles, and so forth. Examples:
• EPH252°/24 = D252X
• EPH145°/24 = D145X
• GEG006°/20 = D006T.
An unnamed waypoint along a DME arc with a radius greater than 26 miles is
identified as an unnamed turn point that is not coincidental with a named
waypoint. Examples:
• CPR338°/29 = CPR29
• GEG079°/30 = GEG30.
When there are multiple unnamed waypoints along a DME arc with a radius
greater than 26 miles, the station identifier is reduced to two characters, followed
by the radius, and then a sequence character. Examples:
• CPR134°/29 = CP29A
• CPR190° /29 = CP29B
• CPR201°/29 = CP29C.

rsvit - Just finished a first read through the FCOM's section on lateral navigation (starts page 11.31.13). Very interesting indeed - cleared up a host of questions about the "seemingly" cryptically named waypoint identifiers appearing on the routes I've been generating in my 737NGX test flights.

 

Thanks again for your help rsvit.

 

Bruce

 

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g_precentralis - Seems our posts crossed in cyberspace.

 

Thank you for your help - your taking the time is much appreciated.

 

Bruce