Offshore Platform PBN/RNP [Archive]

FlightPathOBN

15th Mar 2011, 18:47

oh boy....bring back my old days of being a door gunner....dealing with the guys that had doors...

by a 'pilot' program, I dont mean pilots, I mean a launch or primary customer.

there isnt a lot of info on the site, as this is a business, and one cant post all the secrets!

http://operationsbasednavigation.com/wordpress/wp-content/uploads/2010/11/HeloPro.jpg

The profile shown is for an offshore platform, all of the different lines are what we have to use in a design with the numerous variable...and the difference you see is the performance MDA, where the aircraft operator knows the real time climb with loading and temps, and therefore knows if they have a 4% climb grad, then this is my MDA, if I have 12%, this is my MDA...its a realtime MDA....

okay here goes:

Example:

Karratha to Goodwyn offshore platform:

Using the current NDB approach to Goodwyn, you have a 500' MDA
With the proposed GPS procedure, you have a 350' MDA, and if one goes with a performance MDA (as shown on the profile on the website) one can get to a possible 250'MDA (working on 200'MDA)

With the GPS platform approach, there would be no navigation using weather radar, and the procedure would get minimums and vis below a 300' ceiling, similar situation on approach to Karratha.

From Goodwyn to Karratha:

The current NDB approach has an MDA of 880'.
The GPS approach has an MDA of 550' (note ClassA thru C) with a Class A or H, specific, it could be 250' MDA.

Benefits:

Safety. The procedures put the aircraft at the helipad, and the missed approach is in the box, with no chance of hitting the derrick.

Access. The procedures, with lower min and vis, will allow much more availability of the platform and return. Once the crew is at Karratha, they are on the clock, the Goodwyn crew is still at the clock, any weather delays add significant labor costs. Equipment deliveries and repairs can be 24/7 and potentially save significant downtime costs.

Repeatability. The procedure is set, track miles are known. This can help with costs when fuel prices rise/fall, the costs much more of a known factor.

Environmental Issues. The fuel savings of the procedures will mean carbon savings in the regulatory exchange. The aircraft can also avoid noise sensitive areas.

So....hopefully, that is a little better...

Woolf

15th Mar 2011, 21:03

FlightPathOBN, haven't got time to post in detail just now but for offshore approaches two things spring to mind:

Have you had a look at the (JAR/EU-OPS) GPS assisted airborne radar approach currently used within the North Sea? This is along similar lines and minimas (200' / 3/4nm).

There was an attempt to get away from using radar as a means of navigation for these approaches (as you suggest). It has been recognised however that it is very difficult to control the offshore obstacle environment and radar is necessary to guarantee a clear flight path.

Woolf

catseye

15th Mar 2011, 23:23

OPB

This capability has been around for a number of years in OZ.

http://www.airservicesaustralia.com/publications/current/dap/XMWGN01-124.pdf

http://www.airservicesaustralia.com/publications/current/dap/XLGGN02-124.pdf

Do you have an Australian design approval??? :D

industry insider

15th Mar 2011, 23:27

Also, I understand that Sikorsky has successfully trialled a system they call Rig Approach which is with the FAA for certification.

It flies the aircraft fully coupled to an offset position at helideck height 50' and around 400m at 30 knots I think. If the pilot does nothing, the aircraft commences an automatic go around.It can be used day and night and in any weather.

floatsarmed

16th Mar 2011, 05:11

The only people who may be interested in this in WA are CHC and Bristow.

98% of the flights out of places like KTA are done in clear blue sky so spending dough on more IFR type flight planning software etc won't be on the radar at all.

Also all the graphs and charts that people ever need are already in existance anyway.

Still you could always give the Chief Pilot a ring at CHC Australia 'cos it's his guys who are going to the Goodwin and the Rankin these days. I'm sure he'll be interested?:E

Good luck.

FlightPathOBN

16th Mar 2011, 15:18

Thanks for the interesting replies!

Woolf,
Have you had a look at the (JAR/EU-OPS) GPS assisted airborne radar approach currently used within the North Sea? This is along similar lines and minimas (200' / 3/4nm).
yes I have been involved in the concepts in the North Sea area. The issue with these procedures is the offset, which is where most CFIT incidents occur.
There was an attempt to get away from using radar as a means of navigation for these approaches (as you suggest). It has been recognised however that it is very difficult to control the offshore obstacle environment and radar is necessary to guarantee a clear flight path.
Concur. The significant difference is using the radar for obstacles, not navigation. Procedures are designed with an AAO or Assumed Adverse Obstacles to take into account moving and/or temporary obstacles.

catseye,
This capability has been around for a number of years in OZ.
Concur, the capability has been available, but used little. What I am trying to do is use the procedures already created for fixed wing aircraft, and add the Class A/H for rotary wing. The govt focus has been on Class C/D aircraft for procedure design. And yes, I have significant design experience in AUS.

industry insider,
Also, I understand that Sikorsky has successfully trialled a system they call Rig Approach which is with the FAA for certifica
Yes, I am aware of the Rig Approach concept. This system requires a procedure design per rig...

floatsarmed,
Also all the graphs and charts that people ever need are already in existance anyway.
Yes, there are many charts, but my experience has been they are far too generic, with high mins/vis, usually based on fixed wing aircraft, not helo ops.
98% of the flights out of places like KTA are done in clear blue sky so spending dough on more IFR type flight planning software etc won't be on the radar at all.

Concur on KTA ops, the weather is fairly moderate, which is why this is a good place to begin, as the costs and regulatory approval will be minimal.

Having IFR procedures is very important in helo ops. The accident rates are far too high, and navigating with the weather radar creates too much crew workload.
With procedures, the rigs, approach, missed, holds are defined in the box, and will show on the display. The obstacles have been taken into account in the design, such as the 200' AAO.

Again, thanks for the response!

212man

16th Mar 2011, 17:11

The obstacles have been taken into account in the design, such as the 200' AAO.

I think you may need to raise your AAO somewhat - have you ever seen a Jack-Up under tow? :uhoh:

FlightPathOBN

16th Mar 2011, 23:57

I have...(I used to be a PM for diveops on installs, and recoveries such as Ensco64)

I would not castrate all of the procedures in an area with the parameters of towing around a jackdown..this would be handled as a NOTOM and review any procedures for conflicts, perhaps raise applicable MDA's...we could also provide a course for the towed platform that would not conflict with procedures...

There would be a blanket advisory placed over the area, 25nm, with shipping, advised that any vessel over 200' notify Air Services through the typical NOTAM channels for review...

and, of course, part of certification process to use the procedures, is to arm the helos to deal with non-compliance (one of the side benefits of GPS navigation)

industry insider

17th Mar 2011, 01:07

Flight Path,

Yes, I am aware that the Sikorsky "Rig Approach" system requires a procedure design for each rig. Actually its designed to be more platform rather than rig based.

Each platform requires a unique design because of the low minima and the fact that the system orients the aircraft for landing or automatic GA.

FlightPathOBN

17th Mar 2011, 02:29

Concur,
The specs for the Sikorsky system, to me, are somewhat veiled...
"the pilot enters the FAF, MAPt, MDA, performance, missed approach, and hold pattern" and the aircraft will fly to this...

Well,

Where does the pilot get this information? Enter the FAF...well where is that from? MDA...MAPt...Hold fix...who designs all of this?

Basically, the program appears to allow for an operator to enter IFR approach waypoints, which is technically, per ICAO and common sense...illegal.

While the system may be approved to fly this type of procedure, I doubt if it will be approved for an operator to input, and fly, IFR...

212man

17th Mar 2011, 09:23

Well, if you think I'm going to descend in IMC to 200 ft offshore 'hoping' there are no obstacles in the way, you have another thought coming! The example I used was just one threat - there are plenty of large 'hard' things that populate the sea and are not notified. :confused:

Regarding the SAC Rig Approach procedure, I'm not sure that it does require a design for each platform. On the contrary, I believe it is simply a means of flying a modified OSAP or ARA but with greatly simplified pilot inputs and greatly improved automated functions. The pilot enters the destination rig into the FMS, then sets the inbound course on the Flight Director using the wind direction and obstacle environment as factors. The MDH is set along with the required offset and then the system computes the flight path to arrive at the FAF from the enroute phase, and comences the descents and decelerations as required to the MAPt - based on range/offset distance .It still requires the Radar for obstacle clearance, and indeed displays the required obstacle free sector on the Nav Display. It is still undergoing certification flight testing.

FlightPathOBN

17th Mar 2011, 20:02

Well, the 200' is above the helo deck...and the designs take into account the known obstacles, and some accounting for transitory obstacles. It is unlikely, unless you have a LATS system or a GBAS, that you will get to the 200' mins, but 250' is supported by the criteria and the MOS. and SOAP still has the offsets which cause the CFITs.

Where does all that data come from, the obstacles, MDA and required offsets, location of the hold pattern and obstacle clearance?

What about departures, and the land based destination?

One other issue, I believe this system can only be used when the platform is at least 200nm from land.

CASA/ASA arent going to let this system be used for the land based destinations.

212man

17th Mar 2011, 23:07

I'm not sure what you are getting at, and I say that not in ignorance of procedural design rules, but with practical experience of the offshore IFR operating environment. The obstacle situation is quite dynamic and does not lend itself to any procedure that does not have an adequate means of obstacle avoidance in real time. Although there are are several WAAS and EGNOS procedures being looked at that allow very low minimum decision ranges from the destination, they do not in themselves provide the obstacle clearance assurances during the approach or missed aproach themselves - only from the destination.

The JAR OPS-3 ARA procedure is not well documented, I feel, when compared to the US equivelant - the OSAP. The following link gives some further details of the history and concepts behind the latter, if you are not already aware of them:

http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/list/AC%2090-80B/$FILE/AC90-80B.pdf

You mention the SOAP Trials, so I assume you are familiar with this document?

http://www.caa.co.uk/docs/33/2010001.pdf

FlightPathOBN

18th Mar 2011, 00:43

Your statement is exactly why I have written most of the new procedure guidelines, which will likely be adopted by the operators in the North Sea, and be adopted as the new standard you see in the AUS MOS.

Here is the SOAP procedure overlaid on your current MOS procedure...

SOAP (http://www.flickr.com/photos/45766410@N06/5535671243/lightbox/)

Note the differences? Well...there are none and the same offset is where most CFIT incidents occur...

Lest you forget, my experience is from a helo ops perspective, not bastardizing a fixed wing criteria for the procedure design.

You want to fly more often, at night and inclement weather, and NOT drive into the rig or surf... I can show you how to do that with a level of automation, right now, with what you have...

or you can continue with navigating by offsets using the weather radar for navigation? Keep expounding on your current situation and safety record...

Shawn Coyle

18th Mar 2011, 14:45

FlightpathOBN:
You mention 'most CFIT accidents' - can you provide specific examples of CFIT accidents for oil rig approaches? I'm not that familiar with them.

212man

18th Mar 2011, 15:42

Thanks Shawn - I was going to ask the same question, as I consider myself reasonably au-fait with most offshore CFITs that have occurred in the last 25 years or so, and don't recall many being ARA related. The one that does spring to mind, involving an AS32 L2, was not related to the approach per se, but a mishandled missed approach.

I'm fully in favour of automated, simple to use, approach procedures that bring the aircraft close to the platform - preferrably with AFCS systems that then allow continued coupled flight to close to the commital point. I fully agree that these provide an enhancement to help prevent CFITs, particularly at night and in DVEs. SAC and ECF are both developing such capabilities using elements of their SAR AFCS systems. What I am not in favour of is the assumption that an approach can be designed that does not rely on real time obstacle information using, as a minimum, the radar.

FlightPathOBN

19th Mar 2011, 01:53

With IFR procedures, you are not at elevations where there would be an obstacles other than other aircraft, until you are on final, and within .5nm to .3nm of the rig. This allows the crew to spend the workload on flying the helo, rather than trying to determine offset distances from the rig using a weather radar.

As with any instrument procedure, radar is still actively used to avoid obstacles.

There are many instances on approach to the rig, where, especially at night, the crew becomes disoriented during the offsets, a search on the internet picks up quite a few...but I will hazard this one.

http://www.aaib.gov.uk/cms_resources.cfm?file=/S3-2009%20G-REDU.pdf

C.C.C.

19th Mar 2011, 09:02

There are many instances on approach to the rig, where, especially at night, the crew becomes disoriented during the offsets
At a range of approximately 13 nm, the commander could also see the platform and the crew agreed to descend to 500 ft asl and conduct a visual approach using the weather radar to assist with range information. So this crew stopped using the ARA technique at approx 13nms, and not the offset point as you are infering. As a direct result of this accident there have been significant changes to our SOPs for Night/Poor Visibility Operations to Offshore Installations. During this training it was commented that no-one could recall any CFIT incidents/accidents following the visual segment at the end of an offset night ARA on the North Sea.

I agree with 212man about obstacles. The minimum safe operating altitude for poor visibility (not IMC) offshore operations in Nigeria was raised after a Bell 212 got a bit close to a 3-legged jack-up rig (possibly Trident IX with 518' legs) which had its legs extended whilst under tow in Harmattan and it's movement had not been previously notified to the crew.

FlightPathOBN

21st Mar 2011, 16:10

The MSA, in all of the standards, for ARA is 1500', until on final approach, descend to 1200' when 4.5nm away from the rig. You then descend to the level segment 2nm away from the rig...
It also states that if you observe and obstacle within 4nm of the rig, raise the MDA 200' to 550' (min)

The 1500' is a minimum per the criteria, min segment altitudes are a design, they are not automatic. If there is another rig within 11 nm, the MSA is raised. This MSA assumes 500' ROC (req obstacle clearance), so it plans for obstacles 1000' high...if you have floating platforms taller than this, (I know, virtually impossible, but as soon as I state it, an internet ref will show up!) the design would raise the MSA. Another option would be to issue a NOTAM for the mobile platform with dates, and temporary MSA.

The IFR procedures code in the location of the waypoints with min segment altitudes as a navigation aide. Use the weather radar for spotting uncharted obstacles, there is enough clutter already on the screen..the crew still needs to aviate.

http://www.caa.co.uk/docs/33/2010001.pdf

Here is an accident report compilation for 2000, note page 25 (FITWO/CFIT)
http://ihst.rotor.com/portals/54/industry_reports/Safety%20In%20Oil%20and%20Gas%20Industry%202000.pdf

According to Eurocontrol, since 1976, there have been 7 fatal accidents, with a loss of 94 lives, and 34 non-fatal accidents while on ARA type approach.

Safety Council.

http://easa.europa.eu/communications/docs/ehest/EHEST%20Brochure.pdf

JimL

22nd Mar 2011, 08:29

FlightPathOBN,

I'm sorry, your statement:According to Eurocontrol, since 1976, there have been 7 fatal accidents, with a loss of 94 lives, and 34 non-fatal accidents while on ARA type approachcannot go unchallenged. Is it possible for you to point us at the source of that information.

Jim

FlightPathOBN

22nd Mar 2011, 15:32

Jim,

I have it as a handout from a working group, GIANT (GNSS Introduction in the Aviation Sector...)

"A new offshore approach procedure"

It is a modified SOAP using GPS....much more user friendly with a closer offset and a 15 degree bank to deck instead of 30 degrees in SOAP.

I will see if I can locate an online copy....

212man

22nd Mar 2011, 18:49

A trawl through the GIANT website doesn't seem to show this statistic - which I agree sounds slightly incredible. Do you really think that anyone with more than a passing interest in the offshore industry would be unaware of 41 accidents in the last 35 years?????

GIANT (http://www.gnss-giant.com/home.html?presentation)

Has some good links showing some of the project work to date. One of this forum's contributors was/is involved in the project (and is named in the flight test summary document) so perhaps he might step in and explain?

FlightPathOBN

23rd Mar 2011, 00:29

The document speaks for itself...
Would there be such an emphasis on approach procedures if there were not significant issues?
Helo operators need to evolve with aviation. The accident rates for helo ops are far above acceptable limits.

GPS navigation is here to stay, and has significant safety, navigation, fuel savings, access, and bottom line ramifications.

Evolve, or become a casualty of evolution.

industry insider

23rd Mar 2011, 06:57

I am with you as well 212 and Jim L. I think if we put our heads together, we could almost name all the CFIT accidents resulting from an ARA and I don't think its as many as Flight Path is suggesting.....?

JimL

23rd Mar 2011, 08:24

FlightPathOBM,

You are mixing apples with oranges; yes there have been a number of accidents associated with visual approaches - some with limited visibility as a causal factor - but I am only aware of one recent accident (in Malaysia) that was associated with the ARA (that is not to say that there are not others).

A number of us have the safety of offshore operations as one of our concerns - we monitor such accidents. You still need to justify your statement with some data/information.

You might wish to search back and find the thread on this subject following the REDU accident. It was quite illuminating and provided a great deal of thought on offshore approaches.

Jim

212man

23rd Mar 2011, 08:45

Evolve, or become a casualty of evolution.
Interesting to see your presumptions. As I write I'm sitting in the back of a simulator watching a crew fly an FMS driven RNP APCH approach using a 4-axis autopilot! Fewer assumptions and more facts might be useful in this discussion.....

I guess what might be quite interesting would be to know to what extent your proposals differ from either the GIANT procedure or the FAA OSAP with parallel offset, and why the differences if any? Also, whether you are targeting a particular aircraft and equipment fit, or just generic procedures. what receiver TSO fit are you assuming, for instance?

C.C.C.

23rd Mar 2011, 14:30

Like JimL, 212man & industry insider, when I read your statistic of 41 accidents on an ARA type approach I was very surprised having used the technique since 1981 and never heard of that many ARA related accidents.

Whilst there were a couple of poor weather related accidents, none were on an ARA in the CAA HARP report - http://www.caa.co.uk/docs/33/CAP641.PDF

In the Helios ARA Hazard Analysis there is only one ARA accident - http://www.luftfartstilsynet.no/multimedia/archive/00001/ARA_safety_assessment_1861a.doc

I look forward with professional interest to reading about the other 40 ARA accidents in due course.

JimL

23rd Mar 2011, 15:23

Thanks CCC; the 1981 accident at Alerk Island cited in the 'helios' report was not exactly flown to exemplary standards:AFTER WAITING 7 HOURS FOR THE WEATHER TO IMPROVE THE HELICOPTER WAS FINALLY DESPATCHED AT NIGHT IN IFR TO BE POSITIONED AT AN OIL RIG. DURING THE INSTRUMENT APPROACH TO THE OIL RIG THE CREW DESCENDED BELOW COMPANY MINIMUMS IN ICE/FOG. THE RADIO ALTIMETER WAS UNSERVICEABLE. TO SIGHT THE OIL RIG LIGHTS THROUGH THE ICE/FOG THE PILOT DESCENDED TO 150FT AGL ON HIS ALTIMETER. THE HELICOPTER STUCK THE SEA ICE AND CRASHED. TEMP CORRECTION NOT APPLIED. at the very least, the RADALT being unserviceable should (under European regulations) have prevented a descent to below MDH + 200ft - based upon the lowest regional setting. It also does not say whether this was an ARA procedure.

This accident says more about the operator/pilot than any procedure.

Jim

FlightPathOBN

23rd Mar 2011, 19:05

212,

There are, or can be differences, depending on the level of optimization needed.

The best method is to code the procedure with waypoints, so that the procedure is in the box, and the flight plan can reflect the the instrument procedure. This very easy, using the procedure template, with a fixed rig. Obstacles within the 11nm circle are charted on the plate. Floating platforms require a slightly different design and coordination.

The main difference is the performance real-time MDA, given real time climb gradients. The standard assumes the climb gradient at 2.5% for the missed, so if you have a climb grad of 4 or even 12%, the MDA will be significantly lower, as will the vis requirements.

Using a coded procedure that includes the land based location, the operator knows that the obstacle evaluation has been done, and that the containment area is cleared. The example of Karratha overlaying the RNP approach, the operator knows that Air Services is maintaining the corridor for obstacles and equipment.

The track miles are fixed, so that a rising cost of fuel, can be directly calculated on the bottom line.

Australia is getting set to enact the carbon tax on fuel, so fuel saving ill become very important.

Once one has a chance to see the glass cockpit in action, it really is impressive. I have some GBAS procedures that are rated for CAT III autoland...that is very impressive.

In regards to the stats, I dont know the specifics, other than what what shown in the handout, that were used to justify the GIANT procedure design vs SOAP vs ARA.

Didnt mean to offend...

zalt

23rd Mar 2011, 21:18

CCC

Thanks for that Helios link. A very interesting report.

JimL

This accident says more about the operator/pilot than any procedure.

I'm afraid I have to agree. Sadly the local regulations have not advanced as they have in the North Sea countries either.

C.C.C.

23rd Mar 2011, 22:52

Just found that the above Helios report was also incorporated into a Paper issued by the CAA - http://www.caa.co.uk/docs/33/200906.pdf

In the Norway version the above Bell 212 accident is listed under ARA Related (page 52), but in the CAA paper it is listed under Other (Page 189).

FlightPathOBN

24th Mar 2011, 21:18

CCC,

Thanks for that reference.

As much as I just love studies....

Good reference for ARA, and good ref for GPS, but certainly a disconnect.

If you were using GPS for nav, you would not likely code in an ARA approach, but a PinS or a SOAP. SOAP directly overlays an ARA but with only one offset, so yes, the study is correct that there are no coded ARA's at that point in time, but there were many coded SOAP's and PinS's.

It is a criteria foundation, that an operator cannot enter an instrument procedure, which is why the Rig Approach system will not likely get approval.

There is no reason that the same procedure cannot be pre-loaded, and this would be approved for use.

The procedure design can account for uncompensated baro-vnav, rad-alt or better both, which both is the current standard for MOS charts. (although with baro, the coldest temperature of the location is used, which is why one sees such a difference in MDA between rad-alt and baro)

I am starting to see the point that many of you have made about incidents attributed directly to ARA, especially differences between the regulators and operators. Incidents appear more focused on the operational errors, using FITWO as a catch-all...and given assumptions that there havent been choices, the definitions have not been addressed between approach types in the incident reports.

jonseagull

23rd Aug 2011, 09:12

I am doing a small amount of research into offshore approach's, nothing so high brow as the majority of the discussion you learned gentlemen are having here, I hasten to add, and have come across the following document:-http:[URL="http:////www.caa.co.uk/docs/33/200906.pdf"]

With reference to the discussion about CFIT, I would draw your attention to the Part 2, Annex B CHIRP Events. This does indicate that although, thankfully, there have not been many cases DIRECTLY attributable to the ARA procedure, there is certainly room for improvement. I have been in the fixed wing world now for many years and so much of my rotary experience is now out dated, but, having flown many CAT 3 B auto lands in <200m and flown numerous rig-radar approaches, I know when I felt more comfortable!

I only post this to suggest that just because you can't quote a CFIT accident, it doesn't mean you are immune.