When is time published from FAF to MAP?

jrh

jrh

Well-Known Member
While shooting an approach with a student today, I realized I'm fuzzy on something:

When will an approach chart publish the time from the FAF to the MAP? What criteria determines when the times are printed in the lower corner?

I used to think times were published all the time, except for when the MAP is at the station (such as crossing a VOR).

However, I saw this plate for a VOR/DME approach and there are no times printed:

http://204.108.4.16/d-tpp/0803/06555VD17.PDF

I feel like I should know this already, but I must be having a stupid day today. I skimmed through the AIM and couldn't find an answer quickly. Could somebody please elighten me?

Thanks in advance!
 
jrh said:
However, I saw this plate for a VOR/DME approach and there are no times printed:
Click to expand...

No approach with "DME" in the title should have a timing table published. If you find one, it's an error; reporting it to Flight Procedures would have it NOTAMed out.

I feel like I should know this already
Click to expand...

It would be vastly surprising if you had.
 
tgrayson said:
No approach with "DME" in the title should have a timing table published. If you find one, it's an error; reporting it to Flight Procedures would have it NOTAMed out.
Click to expand...

So is it any approach that involves the use of DME will not have a table?

Here is an approach I used to shoot a lot. I used an ADF to comply with the procedure, but DME would do the job, too, and it does not have a timing table on the plate. It's titled as a plain "VOR" approach:

http://204.108.4.16/d-tpp/0803/00440V16.PDF


Also, GPS approaches never have a timing table for some reason. But this all leads back to my original question--what criteria determines when a timing table is published? Are the reasons for doing it or not doing it explained somewhere in the AIM or another easily accessible document?
 
jrh said:
So is it any approach that involves the use of DME will not have a table?
Click to expand...

No, any approach that has "DME" in the title. In other words, where DME is *required* to fly the final approach.

what criteria determines when a timing table is published?
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The rules you'll generally find in 8260-19C. The above rule is in there, but I don't recall what it says about on-airport navaids. Regardless, they generally don't explain why, only say "don't do this."

My suspicion is that when you have an accurate means of detecting the missed approach point, they disallow sloppy means of doing same; timing is sloppy. BTW, the timing tables are added by the chart designers, not the instrument approach designers. The source document just states the distance from the FAF to the MAP.
 
jrh said:
So is it any approach that involves the use of DME will not have a table?

Here is an approach I used to shoot a lot. I used an ADF to comply with the procedure, but DME would do the job, too, and it does not have a timing table on the plate. It's titled as a plain "VOR" approach:

http://204.108.4.16/d-tpp/0803/00440V16.PDF


Also, GPS approaches never have a timing table for some reason. But this all leads back to my original question--what criteria determines when a timing table is published? Are the reasons for doing it or not doing it explained somewhere in the AIM or another easily accessible document?
Click to expand...

Also, precision approaches (e.g. ILS) will not have a timing table since the MAP is defined by the DA on the glideslope.

Instrument Approach Procedure Handbook 5-59
When DME is included in the title of the VOR
approach, operable DME must be installed in the aircraft
in order to fly the approach from the FAF. The
use of DME allows for an accurate determination of
position without timing, which greatly increases situational
awareness throughout the approach.
Click to expand...
Instrument Flying Handbook 8-23


The MAP varies depending upon the approach flown. For
the ILS, the MAP is at the decision altitude/decision height
(DA/DH). For nonprecision procedures, the pilot determinesthe MAP by timing from FAF when the approach aid is away
from the airport, by a fix or NAVAID when the navigation
facility is located on the field, or by waypoints as defined
by GPS or VOR/DME RNAV.
Click to expand...
Not sure if this helps or not.
 
tgrayson said:
My suspicion is that when you have an accurate means of detecting the missed approach point, they disallow sloppy means of doing same; timing is sloppy.
Click to expand...
My suspicion is that your suspicion is exactly right. The approach is not timed when there is an acceptable way of identifying the MAP using the navaids the chart calls for.

On airport navaids, GPS, DME, ILS (the timing is for the LOC-only approach). All of them have ways of identifying the MAP. It's only when there is not other way to do it that timing is used.

No reason to have "maybe we're here" when you have a way of saying "we're here."
 
looks like you guys knocked that one out. All I have to say is that's a purdy approach. Sorta looks like a flower.

those are 2 things we don't see around Socal, DME arcs and Dirt runways.
 
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