Timing not authorized for defining the MAPt

[fly_safely]

Dear all,

Does anyone know why some charts have written "Timing not authorized for defining the MAPt"?

Could this happen when the DME required is written on the chart?

Thank you,

 

[RussR]

Dear all,

Does anyone know why some charts have written "Timing not authorized for defining the MAPt"?

Could this happen when the DME required is written on the chart?

Thank you,

Could you give an example? I'm not familiar with this note, at least in the U.S.

In U.S. TERPS, if DME is required for the final segment, there will be no timing table (or if the MAP is the VOR). But there won't be a note like you mention.

 

[fly_safely]

Hello,

I can show two examples: Here and here.

In those two examples, it is written DME Required and "Timing not authorized for defining the MAPt".

I am talking about PANS-OPS criteria.

So in U.S. TERPS, when DME is required, we don't have "Timing not authorized for defining the MAPt"?

 

[RussR]

Hello,

I can show two examples: Here and here.

In those two examples, it is written DME Required and "Timing not authorized for defining the MAPt".

I am talking about PANS-OPS criteria.

So in U.S. TERPS, when DME is required, we don't have "Timing not authorized for defining the MAPt"?

Thank you.

In U.S. TERPS, when timing is not authorized (or necessary), a timing table is not published, therefore no note is needed.

I do not understand why Finland is choosing to publish a timing chart, but then say you can't use it. That makes no sense to me, it just results in confusion.

Timing as a method to determine when you've crossed the MAP is a worst-case scenario where no other option exists. For these two example approaches, you DEFINITELY know when you've crossed the MAP, because the MAP is the VOR. So when you get the to-from flip, you're there. There's nothing to time and no point to it.

Additionally, when timing is used, there is a significant allowance for timing inaccuracies in the obstacle evaluation. But crossing a VOR is very accurate - you know exactly when you cross.

In U.S. TERPS, a timing table is only published if it's possible for an aircraft to fly the approach without any other way of determining when it's at the MAP. So a procedure that requires DME will not have a timing table. A procedure where the MAP is the facility will not have a timing table. A GPS procedure will not have a timing table.

 

[midlifeflyer]

I do not understand why Finland is choosing to publish a timing chart, but then say you can't use it. That makes no sense to me, it just results in confusion.

That is really strange. An approach in which (1) DME is required, (2) terminating at an on-filed VOR, with (3) a timing table that is unnecessary because of (1) and (2), and a note prohibiting its use.

I complain all the time about making IFR training more complicated than it is, but essentially having to teach pilots what to completely disregard on the chart goes to a whole new level.