Obstruction Clearance

[ToiletDuck]

ATC gives you this clearance: "Maintain your own terrain obstruction clearance through 3k."

The ceiling is at 2500ft msl. With this clearance can you enter the clouds at 2500ft?

ATC called the flight school and asked this... So we're guessing it's because their radar goes out 35nm and they can give you radar services but you need to be 3k for them to see you...

 

[avbug]

They may be able to see you, but for whatever reason, they are not accepting responsibility for your terrain separation and obstacle clearance until that altitude. It may be that the minimum vectoring altitude in that sector is at three thousand, you don't know.

If the ceiling is at 2,500, are you able to maintain your own separation from terrain? How about other traffic that might be descending down to your location? What are you going to do if you enter the cloud at 2,500 and experience a radio failure?

 

[aucfi]

probably because 3K is the MVA for that area. You have to maintain clearance from obstructions using your OROCA, MSA, or SID/DP

probably something else to be added but thats my thoughts on it...

 

[viper548]

yep. probably below the MVA

 

[ToiletDuck]

but the question is the ceiling is at 2500. ATC was debating on this, my guess is an aircraft had this happen earlier. So are you saying that unless the MSA is 2500 or the oroca is 2500 then no you can't? What solutions would you suggest for this?

 

[minitour]

I believe so. I was given this twice. Once when I was a student pilot (with a CFI) training and once while with a student doing some IMC time.

We were "cleared to ___ via ___ maintain ___ maintain own obstruction clearance through __ proceed direct ___ then on course.". So...it was an IFR clearance, but we had to not hit anything through ___ feet. Probably an MVA thing.

-mini

PS
The other question is...are you in controlled airspace. Yes, you're talking to someone but are you in class G? If so, then you can go through the clouds all you want
91.173
No person may operate an aircraft in controlled airspace under IFR unless that person has—
(a) Filed an IFR flight plan; and
(b) Received an appropriate ATC clearance.

 

[ToiletDuck]

Where is that located about class G. I read it in that everything explained book but I don't have it on me.

 

[avbug]

The statement "maintain your own terrain..." is a legal one. It's a release. It's ATC telling you that they are not responsible, and that you are. It also puts the burden on you...you must be able to maintain your own terrain and obstacle separation.

Not enough information has been provided to answer your question. Have you received your clearance, yet? If ATC won't clear you until getting you on radar and radar-identifying/accepting responsibility, and you're in controlled airspace, then no, you can't enter the cloud. If ATC has cleared you, then you can maintain your own terrain by means of IFR routing/methedology, or visually.

You said that ATC debated something with you. What was the debate, and what was ATC's point?

 

[minitour]

Where is that located about class G. I read it in that everything explained book but I don't have it on me.

91.173...it's in the regs.

-mini

 

[ToiletDuck]

not debate. They called and asked the question. We are debating it here lol. what was ment by class G you can punch through cloud?

 

[minitour]

not debate. They called and asked the question. We are debating it here lol. what was ment by class G you can punch through cloud?

Well what do you need to go into clouds?
Flight plan and ATC clearance right? Yes, if you're in controlled airspace.

The regs don't say "in uncontrolled airspace you need.....".

So...the way I read it, if you want to operate IFR in uncontrolled airspace, you can.

I still can't figure out a "why would you want to"...but there it is...and remember Victor airways are class E...

-mini

PS
If you're doing your -II after your CFI, know these regs by heart! You will probably be asked about them on your oral...just a heads up.

 

[DC8 Flyer]

I used to get this quiet often at my old flight school. My student and I would be out VFR and the weather would push in or vis would go down. We would call approach and get a clearance like this:

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.

Where it could get "hairy" is when the weather got bad enough that the clearane to 2500 would put us in IMC before getting there and we would be in Class E airspace.

 

[minitour]

DC - Love the avatar!

-mini

 

[aucfi]

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

"Legal Stupid"

 

[Vector4fun]

What's the field elevation? That often confuses some folks, ATC clearances are in MSL, while ceilings are in AGL. If the field elevation is 1000', then the base of the ceiling is at around 3500'.


In any case, if there is a published departure procedure, or you can otherwise insure your own terrain clearance, then you're good to go. The controller didn't say "Maintain VFR to 3000'", they asked if you could provide your own terrain separation.

 

[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).