Obstruction Clearance

[avbug]

Quote:XYZ maintain own obstruction clearance to 2500 feet, cleared direct, sqauwk XXXX.Basically, it meant we were cleared direct and given an IFR clearance once we reached 2500 feet. UnquoteNo, you already have your IFR clearance in this case. You're cleared IFR, but must maintain your own terrain separation to 2,500'. You're making the assumption, with the clearance as you've given it, that you're not cleared IFR until reaching 2,500', but that's not what you posted. In the case of what you posted, you're cleared IFR, direct destination, but must maintain own terrain separation to 2,500'. In this case, you do not need to remain visual; you can enter the cloud, so long as you can ensure terrain separation by any number of means. All this indicates is that you're the one who is responsible. Clearly, ATC has told you ATC will not be responsible. Never the less, you are cleared IFR, destination direct.
Seems the board still needs some tweaking. Most of my "buttons" don't work.

 

[A Squared]

I still can't figure out a "why would you want to"...

Perhaps because you're headed to an airport which is situated smack dab in the middle of Class G airspace?

"Legal Stupid"

It might surprise you to know that it's fairly common in some parts of the world, including parts of the US. In fact my carrier (US part 121) has operations specifications specifically addressing IFR ops in Class G airspace. I can think of several airports *with published IAPs* which are a long, long way from the nearest controlled airspace. The only way to get to that IAP is through uncontrolled airspace. Speak not of which you do not know.

 

[Gutenberg]

terrain clearance

Be able to climb 200' per nautical mile, aka a diverse departure, or comply with any published obstacle departure in the front of the approach pubs. If you can get to the MEA, MOCA, or OROCA, you will already be above the MVA. The MVA will be the lowest of all of these.

If the publication says "climb on runway heading," be careful, the TERPsters don't factor in wind.

 

[minitour]

Perhaps because you're headed to an airport which is situated smack dab in the middle of Class G airspace? It might surprise you to know that it's fairly common in some parts of the world, including parts of the US. In fact my carrier (US part 121) has operations specifications specifically addressing IFR ops in Class G airspace. I can think of several airports *with published IAPs* which are a long, long way from the nearest controlled airspace. The only way to get to that IAP is through uncontrolled airspace. Speak not of which you do not know.

I was referring to entering the IFR conditions without the flight plan and clearance. Your 121 carrier addresses that?

I realize there are airports in class G airspace that have approaches and are "far away" from controlled airspace...but why would you want to go to/from that airport without getting a flight plan on file and a clearance?

That's what I don't understand "why".

-mini

 

[minitour]

*double*

 

[A Squared]

...but why would you want to go to/from that airport without getting a flight plan on file and a clearance?

There is no such thing as an IFR clearence in Class G airspace, it doesn't exist. ATC has neither the responsibility nor authority to seperate IFR traffic in Class G airspace.

As for a flight plan on file, can you explain to me what you thnk that will do for you ? (other than activate SAR if you don't show up when you're supposed to)

 

[A Squared]

Be able to climb 200' per nautical mile, aka a diverse departure, or comply with any published obstacle departure in the front of the approach pubs. If you can get to the MEA, MOCA, or OROCA, you will already be above the MVA. The MVA will be the lowest of all of these.

If the publication says "climb on runway heading," be careful, the TERPsters don't factor in wind.

Be careful with this, this is only for airposrts which have been evaluated for a departure. If there is no IAP, the airport probably hasn't been surveyed for a departure.

 

[ToiletDuck]

wouldn't you think that could be argued and wreckless

 

[A Squared]

wouldn't you think that could be argued and wreckless

Anything can (and probably will be) arugued, but hopefully it will be wreck-less.

 

[DC8 Flyer]

Quote:XYZ maintain own obstruction clearance to 2500 feet, cleared direct, sqauwk XXXX.Basically, it meant we were cleared direct and given an IFR clearance once we reached 2500 feet. UnquoteNo, you already have your IFR clearance in this case. You're cleared IFR, but must maintain your own terrain separation to 2,500'. You're making the assumption, with the clearance as you've given it, that you're not cleared IFR until reaching 2,500', but that's not what you posted. In the case of what you posted, you're cleared IFR, direct destination, but must maintain own terrain separation to 2,500'. In this case, you do not need to remain visual; you can enter the cloud, so long as you can ensure terrain separation by any number of means. All this indicates is that you're the one who is responsible. Clearly, ATC has told you ATC will not be responsible. Never the less, you are cleared IFR, destination direct.
Seems the board still needs some tweaking. Most of my "buttons" don't work.

Actually AB, it does mean I have to reach 2500' before I have my ATC clearane, just like a clearanc limit. Since ATC cannot give you a "pop up" clearance at an altitude below their MVA for that area. The use of "maintain your own obstruction clearance" was more of friendly "hey we know your probably in some low weather, climb up to this altitude and we can get you in the system". It all sounds kinda shady but it really works out well if the weather comes in on you.

Keep in mind this isn't something that is practiced every day and probably varies in its use from control facility to control facility and the only exposure I ever had with it was at my home airport. And, the way we used it was, maintain basic VFR until the prescribed altitude and then you've got your clearance.

I should have clarified in my earlier post that the MVA for the area was 2500 feet. sorry for the confusion.

 

[minitour]

There is no such thing as an IFR clearence in Class G airspace, it doesn't exist. ATC has neither the responsibility nor authority to seperate IFR traffic in Class G airspace.

As for a flight plan on file, can you explain to me what you thnk that will do for you ? (other than activate SAR if you don't show up when you're supposed to)

So you couldn't file from ABC airport Direct DEF airport (using GPS) and have the flight be entirely in class G airspace and still get your clearance, etc?

-mini

 

[ackattacker]

Actually AB, it does mean I have to reach 2500' before I have my ATC clearane, just like a clearanc limit. Since ATC cannot give you a "pop up" clearance at an altitude below their MVA for that area. The use of "maintain your own obstruction clearance" was more of friendly "hey we know your probably in some low weather, climb up to this altitude and we can get you in the system". It all sounds kinda shady but it really works out well if the weather comes in on you.

Keep in mind this isn't something that is practiced every day and probably varies in its use from control facility to control facility and the only exposure I ever had with it was at my home airport. And, the way we used it was, maintain basic VFR until the prescribed altitude and then you've got your clearance.

I should have clarified in my earlier post that the MVA for the area was 2500 feet. sorry for the confusion.

Sorry, I go with avbug on this one. I routinely operate part 121 out of an non-towered airport (but controlled airspace) and receive a similar clearance below MVA. We are IFR once we receive such a clearance, but the controller is not guaranteeing obstruction clearance. He is guaranteeing seperation from IFR traffic. The whole class G issue is separate. Typically, an IFR clearance out of an "uncontrolled" airport will sound more like "upon entering controlled airspace, cleared to XYZ via as filed etc etc" The purpose of an IFR clearance is to provide separation from other IFR traffic. Terrain clearance is provided by published procedures and routes, or, in radar contact, minimum vectoring altitudes. If you received your clearance on the ground, the phrase "maintain your own terrain and obstruction clearance" is unnecessary since it is presumed you are complying with IFR departure procedures immediately upon liftoff. If you pick up the IFR aloft, but below MVA, then you are VFR when you call... hence you cannot be presumed to be complying with published IFR procedures. You could be anywhere since you are just using visual seperation from terrain. Hence the controller must remind you that your "pop-up" IFR clearance is not providing terrain seperation. You must provide your own, either by maintaining visual from the terrain or compying with a published procedure (or, in many instances, simplying climbing 200'/nm as somebody mentioned). However, you are IFR as soon as you hear "cleared via....". You can enter the clouds if you can legally and safely maintain terrain and obstruction clearance.

 

[A Squared]

So you couldn't file from ABC airport Direct DEF airport (using GPS) and have the flight be entirely in class G airspace and still get your clearance, etc?

No, there is no such thing as a clearance in Class G Airspace. A clearence is an ATC thing, and ATC has no authority, responsiblity or purpose in Class G airspace.

 

[minitour]

No, there is no such thing as a clearance in Class G Airspace. A clearence is an ATC thing, and ATC has no authority, responsiblity or purpose in Class G airspace.

hmm...interesting...learn somethin' new every day.

-mini

 

[ackattacker]

So you couldn't file from ABC airport Direct DEF airport (using GPS) and have the flight be entirely in class G airspace and still get your clearance, etc?

-mini

That is correct. ATC will not give you a clearance in class G airspace. However, the situation you describe is extremely rare in the 48 states. You'd be hard pressed to find an area where you can fly cross-country in IFR in class G airspace (remember that you still have to comply with IFR altitudes and height above terrain). Airways are class E, so you have to avoid them... and forget about shooting an approach. If the airport has an approach, I guarantee you it has controlled airspace above it. But if your flying across northern Alaska or something below 14,500' then you can fly through all the clouds you want. You could also fly transatlantic down low without talking to anybody (until you reach the ADIZ, then you better start talking).