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Obstruction Clearance

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ToiletDuck

Ninja
Joined
Apr 23, 2005
Posts
598
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...
 
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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?
 
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...
 
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.
 
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?
 
ToiletDuck said:
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?
Click to expand...

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.
 
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.
 
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.
 
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.
 
minitour said:
I still can't figure out a "why would you want to"...
Click to expand...
Perhaps because you're headed to an airport which is situated smack dab in the middle of Class G airspace?
aucfi said:
"Legal Stupid"
Click to expand...
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.
 
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.
 
A Squared said:
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.
Click to expand...

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
 

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