VOR navigation question

[aterpster]

So, you will have a diverse departure (or at least an evaluation of one) at every IFR airport regardless of size or ATC services. You will only have a diverse vector area at larger airports that have the radar coverage to support it (and the need for it - note that none of the NYC airports have a DVA, for example).

If an airport has takeoff minimums and no runway restrictions, no ODP or departure restriction ("Runway 13, climb to 1,300 before proceeding on course") then that airport is diverse for every runway (at 400 HAA) turn as you wish absent ATC restrictions to the contrary). As to DVAs, my old home drone (KEMT) is a small airport with a DVA. With the advent of FUSION it moved from a radar hole to radar to the ground. The proximity to Class B likely has something to do with the establishment of this DVA. It certainly isn't because of a lot of IFR departure traffic.

 

[luvflyin]

That's incorrect. The two are separate procedures and serve separate functions. Every airport with an instrument approach is evaluated for a diverse departure, to see if the obstacle and terrain permit it. This allows you to climb and not hit anything if you follow any limitations in the diverse departure, regardless of whether it complies with an ATC clearance or not. It's evaluated to 25 or 46 nm from the airport. Typically there is an airway within that distance, though in some remote areas that may not be true. Radar coverage is not required or considered.

A diverse vector area tells ATC what range of headings they can assign on departure in order to get the airplane to their MVA. It's very much an ATC function, and these are developed in coordination with ATC and consider their radar coverage.

So, you will have a diverse departure (or at least an evaluation of one) at every IFR airport regardless of size or ATC services. You will only have a diverse vector area at larger airports that have the radar coverage to support it (and the need for it - note that none of the NYC airports have a DVA, for example).

Yeah. They shoulda come up with different words to describe those things instead of using 'diverse' in both.

 

[Palmpilot]

...Look at SQL, for example.

View attachment 101244

It clearly failed a diverse departure evaluation, but that's a separate issue. So a departure route was established involving the SJC R-281, etc.

And a DVA was established allowing radar vectors. Note that here it just says "headings as assigned by ATC", there is a separate part of the DVA form that ATC gets telling them what range of headings they can assign:

View attachment 101245

It's odd that they cite both obstacles and ATC as reasons why Runway 30 minimums are N/A. I can understand the ATC part due to the proximity of SFO, but I'm not aware of any obstacles that could not be dealt with through sufficiently high minimums. Here's the view off the departure end of Runway 30:



https://www.google.com/maps/@37.515...4!1su8oGlt8ADHDU-p7Ue3vs0g!2e0!7i16384!8i8192

There's a ridge with towers at 1569 MSL, but that's 14 NM away:

https://skyvector.com/?ll=37.61087717160527,-122.3874664271249&chart=301&zoom=2&fpl= KSQL 3742N12227W

Due to the fact that the wind most often favors Rwy 30, when the ceiling is high enough SQL Tower has been issuing a somewhat complex set of instructions to get IFR departures turned southwest-bound while airborne. To help pilots deal with it, the San Carlos Airport Association has a description and unofficial chart on their Web site:

http://www.sancarlosairport.org/runway-30-vfr-to-ifr-departure-guidance/

A NASA ASRS report of mine may have played a role in the publication of that guidance. I filed it after badly screwing up the departure due to having trouble deciphering what I wrote down when I was given the departure clearance. (Fortunately I knew enough to stay away from the SFO final approach course.)

 

[Palmpilot]

Not sure if I know who I am, but it is a long standing policy from 7110.65Z, 4-1-1 Navaid Use Limitations and 4-1-2 Exceptions. The policy was modified to allow aircraft equipped with GPS as an exception. Senator Thune's office was very helpful in getting the FAA to add the GPS exception. With the new service volumes, it is probably appropriate to update the guidance in 4-1-1 to reflect the possibility of increased SSV.

It's interesting that 4-1-2 still uses the equipment codes from the obsolete FAA flight-plan form instead of the ICAO ones. Now I don't feel so bad about telling ATC that I'm /G or /A.

 

[dtuuri]

Not sure if I know who I am, but it is a long standing policy from 7110.65Z, 4-1-1 Navaid Use Limitations and 4-1-2 Exceptions. The policy was modified to allow aircraft equipped with GPS as an exception. Senator Thune's office was very helpful in getting the FAA to add the GPS exception. With the new service volumes, it is probably appropriate to update the guidance in 4-1-1 to reflect the possibility of increased SSV.

I believe we're both talking about Greenville, ME (3B1) which is on V300, so 4-1-1 shouldn't apply in the first place and even if it wasn't within an airway by the time a departing aircraft climbed to MEA—it (the departing a/c) would be.

4-1-1

1. ALTITUDE AND DISTANCE LIMITATIONS

When specifying a route other than an established airway or route <snip>​

 

[Trogdor]

@RussR So why would you have a DVA if you already have a DD? i.e. after 400AGL I'm good. Why do I need ATC at that point? Noise abatement?

 

[luvflyin]

@RussR So why would you have a DVA if you already have a DD? i.e. after 400AGL I'm good. Why do I need ATC at that point? Noise abatement?

If I may butt in. You don’t need the DVA. It’s for them. It allows them to Vector you below the Minimum Vectoring Altitude and put you right where they want you.

 

[RussR]

If I may butt in. You don’t need the DVA. It’s for them. It allows them to Vector you below the Minimum Vectoring Altitude and put you right where they want you.

That summarizes it succinctly. Thank you.

 

[aterpster]

That summarizes it succinctly. Thank you.

So far as I am concerned, DVAs should be at any IFR airport where ATC has vectoring capability. The DVA makes vectors below MVA safe, and permits vectors below MVA into an area of higher MVA. At first, the program had hiccups because controllers were going to be required to cite any climb gradient to the pilot. The controller's union balked.

 

[luvflyin]

So far as I am concerned, DVAs should be at any IFR airport where ATC has vectoring capability. The DVA makes vectors below MVA safe, and permits vectors below MVA into an area of higher MVA. At first, the program had hiccups because controllers were going to be required to cite any climb gradient to the pilot. The controller's union balked.

I can't fault them for not wanting to have to do that, issuing the Climb Gradient to each pilot.

 

[Trogdor]

Oh, I see. Thanks!