Parallel Entry Question

[luvflyin]

QUOTE="RussR, post: 3135732, member: 8794"]That's just kind of an internal thing. The numbers correspond to the obstacles on the form 8260-9 where each segment is documented. Missed approach holding patterns, however, are not documented on the 8260-9, but on form 8260-2, which does not number the obstacles. So when the maps were made, a random symbol was used to identify those "un-numbered" obstacles. You'll see @, #, $, pretty much any symbol on the keyboard used depending on specialist preference, and it's just to match up the info in the table at the bottom with the info on the map itself.

Maps produced using the latest software will not have obstacle numbers, as the software puts the obstacle info in its own box pointing to the obstacle (so there's no need for a reference number).

Random example:

View attachment 99555

Way more than you wanted to know, I'm sure.

Don't stop there. Explain the digital references to the towers (DOF).

You mean like (406), (780) etc, and/or the 06-020379? And while we're here, what's the difference between a Tower and an AAO?

EDIT: Found what DOF was, digital obstacle file so I get the ##-###### numbers.

 

[aterpster]

You mean like (406), (780) etc, and/or the 06-020379? And while we're here, what's the difference between a Tower and an AAO?

EDIT: Found what DOF was, digital obstacle file so I get the ##-###### numbers.

AAO. Assumed adverse obstacle. The additives to the lateral position and vertical height depends upon the accuracy code assigned in the DOF. Beyond the FAR 77 surfaces 200 feet is added to high terrain, because a tower or other structure as high as 199 feet can be erected there without requiring notice to the FAA.

 

[RussR]

Don't stop there. Explain the digital references to the towers (DOF).

Thanks for taking the time to share your knowledge. No idea about the digital reference though. I saw the number and would guess height or elevation, but no idea about the “AER,” ETC.

You mean like (406), (780) etc, and/or the 06-020379? And while we're here, what's the difference between a Tower and an AAO?

Hah, no problem. @aterpster already hit on most of it.

On that map, the segment the obstacle applies to is the first line of each label, then the obstacle information is on the second line.

So for Circling Cat A Tower (406) 06-020379, that means the obstacle is the "controlling obstacle" (in this case, the highest obstacle) in the Cat A Circling area. It is a Tower (typically means "antenna tower", although for TERPS purposes it really doesn't matter what it is, just that it's there - and it's whatever the survey company decided to enter). The height is 406 ft MSL. And the obstacle ID # is 06-020379. The "06" here identifies the state, in this case California. And the "020379" is just its identifier. No magic to that, that I know of. Might just be the 20,379th obstacle entered in California.

Some have "AAO" as the obstacle. As Wally said, this is just an assumed obstacle. Basically, it is assumed that everybody is going to put up a 200 ft tall ham radio antenna in their backyard tomorrow, because they can do so without informing the FAA (outside a certain distance from the nearest airport, typically 10,000 or 20,000 feet from any runway end).

Some of the segment labels are more difficult to read, especially the one on the bottom of the map, "LNAV ZILVI to KOKB:RW25:AER". That just means it applies to the LNAV final, the segment from ZILVI to the KOKB runway 25 Approach End of Runway. That's it, nothing earth-shattering. Those labels are generated by the software, and can be changed by the specialist if so desired, so you may see several different styles of wording the same type of information on different maps.