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Approaches to Rigs?


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I was wondering if someone could explain to me how most offshore operators get down from their enroute altitude when where is an issue.

 

I understand that OSAPs and HEDAs exist but what is the process for gaining approval to use them, who designs them, and how/how often are they used in practice?

 

Has anyone developed RNAV or GPS approaches for oil rigs like they have for helipads on solid ground? Would it even make sense to do this?

 

Thanks....

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They're part of the company's ops specs. Approval is in the ops specs, along with the procedures.

 

They're used all the time. An OSAP is like a GPS approach to a helipad, but the direction of the final approach is up to the crew, within wind limits. You set up the final approach into the wind, within the number of degrees variation allowed by the specs, normally 10 degrees. The normal way it's done is to take the reported wind and make that the final approach course. Getting down from the enroute altitude is part of the approach procedure, and it's all specified. I'm not sure what you mean by "when there is an issue".

 

The design is generic, and all you really have to do is have confirmed coordinates for a rig in order to fly an approach to it. You need weather reporting, either at the destination or two reports within a specified boundary. HEDAs are just enroute descent areas, and anyone can survey one. There must be no obstacles within the specified area. It's not an approach, just an area clear of obstacles where you can descend into VMC and then continue VFR to a destination. It's Class G airspace out there, so VFR minima are whatever the ops specs say. I used to fly to VFR minima of 300/2 in mediums. Small ships had 500/3.

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Thank you Gomer! I meant "when weather is an issue" but it you figured it out.

 

It sounds like OSAPs make developing "traditional" RNAV/GPS approaches to ships and platforms unnecessary? It also sounds like OSAPs are more useful and more flexible.

 

Does anyone know how approaches to rigs are handled in other countries? Are "OSAP-like" procedures being used in Asia/Europe/South America/India?

 

Agian, thank you for the help...

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They're part of the company's ops specs. Approval is in the ops specs, along with the procedures.

 

They're used all the time. An OSAP is like a GPS approach to a helipad, but the direction of the final approach is up to the crew, within wind limits. You set up the final approach into the wind, within the number of degrees variation allowed by the specs, normally 10 degrees. The normal way it's done is to take the reported wind and make that the final approach course. Getting down from the enroute altitude is part of the approach procedure, and it's all specified. I'm not sure what you mean by "when there is an issue".

 

The design is generic, and all you really have to do is have confirmed coordinates for a rig in order to fly an approach to it. You need weather reporting, either at the destination or two reports within a specified boundary. HEDAs are just enroute descent areas, and anyone can survey one. There must be no obstacles within the specified area. It's not an approach, just an area clear of obstacles where you can descend into VMC and then continue VFR to a destination. It's Class G airspace out there, so VFR minima are whatever the ops specs say. I used to fly to VFR minima of 300/2 in mediums. Small ships had 500/3.

 

Why the difference between medium and small?

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Mediums have two pilots, and can go IFR if necessary. Small ships have one pilot, no instrument capabilities, and one engine. Where I worked, the split was actually between twins and singles, and that made no sense to anyone who was actually flying, but there it was. If you were flying a BO-105 or an AS-355, you were expected to head out offshore with weather of 300/2. If you didn't, you wouldn't last long. Note that 300/2 is lower than the descent minimum altitude in a HEDA. The minima for an OSAP is 200/.66, in effect 3/4 mile vis, and at night it's 300/1. Going offshore in that weather, without enough fuel to return to the beach, is enough to make one concentrate on maintaining a heading.

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Weather minima are set in the company's ops specs, and will vary from company to company. It pretty much comes down to what the company wants to use for minima, and I've seen some, years ago, that used standard FAA Class G (airspace classes didn't exist back then) minima of clear of clouds. Aircraft would go out and back flying at 100' or lower, with virtually no nav guidance other than a compass and watch. GPS wasn't even dreamed of, and LORAN was often installed only in larger aircraft. For several years I flew a 206B from an offshore platform >100 NM offshore, with only an ADF for navigation. That was usually tuned to a commercial radio station onshore, because there were no operable NDB stations that were usable out there. My minimums were 500/3, though, not just clear of clouds. But even 500/3 is difficult when you only have a map, compass, and watch. The map isn't much use, so we had to quickly learn the Gulf, and recognize all the platforms from several miles away. We also learned to read the waves, and from them the wind, and make the appropriate wind course corrections. With GPS, it all became easy and I suspect most newer pilots out there would find it tough to navigate without it. I may be wrong about that, but I sort of doubt it.

 

We used to fly IFR, and fly OSAPs, to the same minima using LORAN, which was, and still is, much less accurate. The saving feature is weather radar in ground mapping mode, which shows you exactly where the platforms are. Without radar, the approaches wouldn't be possible, even with GPS. When you're at 200', and the booms on the rigs can stick up 500', you want to know exactly where they are.

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.. don't even get me started on my Agusta A119 instructor.... WHEW! :blink: :huh:

 

Yeah, he was a real hard@ss.

 

 

Gomer,

 

You posted a link some years back of the MMS platform database. Any chance you kept up on that link? I'm trying to locate it but having difficulty. Thanks, and sorry for the thread hack...

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Sorry, I haven't kept up on that for a couple of years. It should be findable with Google if it still exists, and it should. The MMS is a government agency, even if there has been much hilarity and ribaldry occurring there in the past.

 

Yeah, they are BOEM, now, but Google hasn't helped. Thanks, though. Much appreciated.

 

Again, sorry for the thread hijack.

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The old link I had bookmarked still worked. The names have changed to protect the guilty, but DNS forwards you to the correct URL.

http://www.gomr.boemre.gov/homepg/pubinfo/freeasci/platform/freeplat.html

 

You want the Platform Locations file, and you'll need to do some manipulation of the file. I used to import it into a speadsheet, delete all the unneeded columns, then run a macro on the lat & lon to get them into the proper format. I just looked, and I can't find the spreadsheet I had set up to do the conversions. If you click on the filename on the site, you'll get a list of all the data fields and what they represent. Probably all you need are the block, number, lat, and lon. The lat & lon are in decimal degrees, with the lon being a negative number, so you'll have to convert that to the format your GPS uses, probably degrees and decimal minutes. It's doable with a spreadsheet, but I no longer have the ambition to recreate it.

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www.blockinfo.com might have what you're looking for. Otherwise, you can always buy a GOM offshore chart and do it the old fashioned way: plot out what you're looking for.

 

Yeah, the chart doesn't show the operator or deck weight limit. ;-)

 

I've used blockinfo.com, and it is valuable info, but it isn't a complete listing, whereas the BOEM database will be. (I know the guy that developed it and we were based together about 7 years ago)

 

I'm flying a contract right now that we can launch for any offshore destination and I'm in a reasonably heavy helicopter so the deck limit makes a difference in mission profile planning and we don't always get that info on initial contact.

 

 

Thanks, GOMER, much appreciated. I'll dig into it to see how we can't make us of the info there.

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If you want deck load limits, you probably need to incorporate one of the other files. I think the platform master has all the info you need, and probably a lot more. It will take a little work, but it's possible to combine the files and get the necessary info into one spreadsheet, which can then be turned into any filetype you like, for viewing on any device. I once had all that platform info in a Copilot database for Palm, which was a flight planning tool, and it worked very well. Now Android is much more commonly used than Palm, and it lets you use almost any file type you like.

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  • 2 weeks later...

To stay alive get back to basics.what if u had nuffin and were nakied??so u get winds cater for drift,and know that wx is goin to be bad.u go by time and hope like hell u have not drifted too far off en route u could trk posn with one odd rig sighted.coming close u manage to get a erratic ndb lock.u know there are no obsts near this rig.u r in the vicinity on instruments.the other guy is positively monitoring u and glancing out.rad alt is set,u won't go below 200 ft.u finally get to 200 ft and break cloud,sea is rough and u know no wave will sock u here.sight a rescue boat nearby and any needed descent say from 300 ft is around this.its pouring but and since u r out of cloud both look out and sight the rig.mebbee u do a tight go round and then with tight monitoring due to edgy wind, finally safely come in !Hooray!! kojak(kopterkojak@utube

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