Obstacle Departure Procedures vs ATC IFR Clearance Vectors

[Talan2000]

Hi guys,

I sort of have mixed emotions about having completed the last Instrument Training Lesson! I guess it's ok to post training questions here:

In a non syllabus flight today from KSEE to L35 (Big Bear).
http://peaware.pilotedge.net/flight.cfm?id=84361

1. Wanted to be thorough so I looked up KSEE's Departure Procedure

http://skyvector.com/files/tpp/1501/pdf/SW3TO.PDF

"DEPARTURE PROCEDURE: Rwys 9L, 9R, 27L, 27R,
climbing right turn on heading 165° and MZB R-076 to MZB
VORTAC. Rwy 17, climb on heading 165° and MZB R-076 to
MZB VORTAC. Rwy 35, climbing left turn on heading 165°
and MZB R-076 to MZB VORTAC. "

I filed: JLI PSP YUCCA

I was cleared: HDG 340 Radar Vec JLI... 3000 expect 10000 in 5

I queried the Delivery - Stating that KSEE had a departure procedure requiring me to go to MZB. And whether I should do so. ATC seemed confused and said since I was flying H340 and going to JLI I didn't need worry about that...Uhhh huh.. I rogered up, but I think this was an incorrect departure.

What do you much wiser and more experienced guys think? It's WAY out of the way to go to MZB and also it sends you right through the B approach path for KSAN.

Have I just found another weird thing ala the KSNA "immediate" 15 degree left turn at the end of 20L? Should (and would) real ATC clear me to MZB to gain altitude. I didn't love flying north at 3000 but I was immediately cleared to 10000. There's a 1200ft "mouintain" right near KSEE...

Todd
N3298S

[Peter Grey]

The simple answer here is the the ATC heading overrides the ODP and guarantees that you won't hit any obstacles as long as you maintain a 200 ft/nm climb rate.

So as long as you have a further climb instruction within 15 miles of departure you are all set.

In the real world you would be assigned heading 340. Our departure headings are based on real world heading assignments.

Let me know if you want more details. A good starting point for reading up on this would be AIM section 5-2-8. Your question is answered in 5-2-8 c 2:

ATC may assume responsibility for obstacle clearance by vectoring the aircraft prior to reaching the minimum vectoring altitude by using a Diverse Vector Area (DVA). The DVA has been assessed for departures which do not follow a specific ground track. ATC may also vector an aircraft off a previously assigned DP. In all cases, the 200 FPNM climb gradient is assumed and obstacle clearance is not provided by ATC until the controller begins to provide navigational guidance in the form of radar vectors.

If you want some more reading I'll refer you to this thread: viewtopic.php?f=5&t=4022&p=25677 where another member had a similar question.

[Talan2000]

Peter

Wow, your knowledge truly is encyclopedic!

It strikes me as odd (dumb) that KSEE would publish this departure procedure than if they never use it... I guess it's in the one case where someone isn't given a vector heading, pays attention to this "diverse vector area" and follows the MZB obstacle procedure -- which looks like it would wreak havoc with the B airspace...

Thanks

Todd

[Peter Grey]

TERPS requirements require that an ODP is available out of all airports that have IAPs (or a proven need to not need an ODP due to extreme flatness).

These ODPs are not required to flow with traffic at all.

For proof of this I submit the LAX ODP for consideration:

Rwys 24L/R, climb to 2000 heading 250°, then climbing
left turn, thence... Rwys 25L/R, turbojet climb to 2000
heading 250°, then climbing left turn, thence...nonturbojet
climb to 2000 heading 250°, at the SMO R-154
turn left heading 200°, thence...
...climb direct SLI VORTAC, then climb on course.

Turning direct SLI at 2000' off of 24R is the perfect way to ram a 25L departure from LAX. If you miss that one you'll hit the HHR departure, or the LGB departure.

[Talan2000]

Yeah, I would never have keyed in on any of this stuff were in not for the I-11 (?) with the ODP "climbing hold" without efc thence onward...

I would have been blissfully ignorant.

Now, I saw the Takeoff mins, looked at the pub. also looked at the Diverse Vector Area pub (what's that!), and knew enough to be scared -- ie "it's authorized to fly the ODP even if it's not assigned" and your clarification in this and the linked thread helps my little pilot brain understand and be happy with
"UNLESS ATC gives you a vector."

Thanks again

Todd