odp , sid departure question from tower controlled airport in radar environment

I have an ifr departure question.  When do you opt for the odp in the take off minimums section if you are being provide a sid or radar vectors whilst the tower is open

I was looking  and studying departure  procedures but at times I get confused about the following point because the diverse departure concept, sid and requirement to use the odp can be confusing at a tower controlled airport 

I just randomly picked an airport just to illustrate this question

Lets say atc provided a sid (in this case from KYTS ) Knoxville . Lets say they assign the Knoxville 7 dep. that departure is pretty clear on what you would do as illustrated on the sid  for each runway. This sid requires radar . I would expect that you would most likely get radar vectors  pursuant to , and in accordance with the sid. 

Now if you review the take off minimums  tab in foreflight for example   then you will see an obstacle departure procedure for the runways that is different than the  noted sid.  ( which makes sense )

so at this airport it says it is attended continuously, unless i missed it i think the tower is always open providing service.  then under what circumstance would you fly the odp noted in the take off minimums. 

The odp is different than the stated sid ( again makes sense ) and given you will get from atc  radar vectors, or a sid in a clearance then  when would you default to the takeoff min instruction and fly the  obstacle procedure  ( odp ) in the take off min section. I know under part 91 it is optional. I could understand flying the odp when the tower is closed as a good option not to hit anything, but under radar control are you not going to fly the sid (if given in the clearance )or some other departure instructions given by the tower. This is a towered airport so im just not sure when in a case like this you would opt for the odp. advice please .

 Odp's make lots of sense at non towered airports ,and where you might pick up a clearance  (where  it is up to the pilot to find a safe way out of the airport), to the enroute structure consistent with the clearance. but not sure when you do this at a atc controlled towered airport. 

thought

Ptflyer

Ace Any FAA Written Test! Actual FAA Questions / Free Lifetime Updates The best explanations in the business Fast, efficient study.

Pass Your Checkride With Confidence! FAA Practical Test prep that reflects actual checkrides. Any checkride: Airplane, Helicopter, Glider, etc. Written and maintained by actual pilot examiners and master CFIs.

The World's Most Trusted eLogbook Be Organized, Current, Professional, and Safe. Highly customizable - for student pilots through pros. Free Transition Service for users of other eLogs.

Our sincere thanks to pilots such as yourself who support AskACFI while helping themselves by using the awesome PC, Mac, iPhone/iPad, and Android aviation apps of our sponsors.