North Sea Weather Considerations

[coatimundi]

We were a bit bewildered today offshore in the Central North Sea when we were told that our crew change helicopters weren't coming because the sea state did not permit launch of the standby vessel's FRC. The conditions were suitable for Dacon Scoop deployment, which until today had been deemed adequate to permit flying.

So, what's the scoop :} on this one chaps? We don't mind if you don't come because the weather is c:mad:p, if you don't want to fly we don't either, but why the sudden (and unannounced) change in parameters?

[hands_on123]

The whole issue of Daycon scoop has been running for years, some pilots dont think its a adequate form of rescue, some do. BALPA thinks it's an unsafe form of rescue.

[MyTarget]

Well it might be worth checking with your company and the contract they have with your aviation provider. I am sure the details will be in the contract!

[HeliComparator]

The pilots in CNS and BALPA have never believed that the Dacon Scoop represents valid rescue equipment. Some trials were done recently to justify it, but they were laughable since not carried out in representative conditions, then results extrapolated by someone with an outcome in mind.

The Dacon scoop is no doubt capable of fishing you out of the sea in rough conditions, only trouble is it will kill you doing so.

You can then argue that the probability of you ending up in the water is pretty low, the probability of that happening when its too rough for FRC is even lower, therefore the overall risk might be acceptable. Or you might think that its not acceptable when the alternative is to carry out the flight tomorrow.

HC

[Leaky Valve]

PFEER AND THE DACON SCOOP (http://www.shipsandoil.com/Features/Dacon%20Scoop.htm)

[squib66]

coatimundi

What type of helicopter normally does your flights?

It will be interesting to see if the Canadian decision (based on a TSB recommendation (http://www.tsb.gc.ca/eng/rapports-reports/aviation/2009/a09a0016/a09a0016.asp#sec4_2_2)) to stop flights when the sea is out of limits for the helicopter's floatation systems is acted on elsewhere. The Canadian equivalent of Oil & Gas UK said they were doing this because 'safety is first'.

[bondu]

To add to 'squib66s' comments.

The EC225 and S92 both have floation system which are certified up to 6m waves. The sea state in parts of the CNS today were as follows:

Goldeneye Sig Wave 7.0m Max Wave 10.2m

Forties A Sig Wave 6.9m Max Wave 11.0m

Unity Sig Wave 6.8m Max Wave 11.9m

Nelson Sig Wave 6.7m Max Wave 9.9m

ETAP Sig Wave 5.8m Max Wave 10.5m

I could go on, but I think you get the picture. The trials on launching FRCs (fast rescue craft) show that 5.5m seas are the limit. Anything over 5.5m means that the only method of recovery is the DACON Scoop. BALPA policy is that commercial flights should not depart if the primary method of recovery is the scoop. I say BALPA policy, but it is really common sense! UK Oil and Gas did release a piece of video showing the trials of the scoop done in 2009, in very gentle sea states. Having watched the video evidence, I don't want to get anywhere near a DACON Scoop!
So, if you were a passenger waiting for a flight today which didn't materialise, then it was probably because the crew were using their common sense! North Sea pilots want to go home at nights just like everyone else - they will not take un-neccessary risks. If it is safe to fly, they will do so. If not, they won't!

bondu

[Droopy]

bondu, is BALPA policy is that commercial flights should be depart if the primary method of recovery is the scoop.

what you really meant to say?

[bondu]

Droopy,

Yes indeed!! Thank you - edit now made!:ugh:

bondu

[squib66]

BALPA Video (http://www.youtube.com/watch?v=PtztU8eXTAs)

[hands_on123]

Re: Video.

Blimey! Good luck with that!

[bondu]

If you watch the video, you will notice that the 'live' person recovered to the deck is wearing an orange survival suit, but the 'live' person (which looks suspiciously like a dummy) being 'captured' by the scoop is wearing a yellow suit! :*

The editing of this film was done by Oil and Gas UK before BALPA got a copy.

Also note the sea state during the trial - not quite the 7 to 11m we had today!

bondu

[helimutt]

coincidentally, I fly North sea now, and my step father worked on the boats for the Dacon scoop trialling. He reckons the dummies had to have strengthened titanium joints to keep them together during the high sea state trials, and he also asked me were i ever to suffer a ditching, never to have to be recovered by dacon scoop if I survived said ditching, because it would be a shame that i was killed during rescue! Anything over about 4m sea state and it's not pretty.

and yes, that video does show a dummy during the recovery.

[herman the crab]

Bears a resemblance to the Jason's Cradle - works on a similar principle but is more rigid. Looking at the video I think the problems and casualty injuries would e very similar.

Never had the pleasure of being in one, but having seen the trials on the local pilot boat we (a government operation) decided against it. The RNLI use them but when it was suggested that we consider it on my current command I politely suggested that it was put somewhere the sun doesn't shine.

HTC

[lowfat]

I find it hard to belive that any one would chose to launch in a situation where the dakon scoop is used as a primary source of rescue.

When the chips are down .
A large Saftey vessel charging at me in large seas after I have just survived a helicopter crash is really the last thing I want.
Okay if it's all gone wrong pick me up... But should I plan for this?

Is that first beer worth the dacon scoop,, I think not...

[coatimundi]

Good responses all, chaps, but perhaps I should have made my point a bit clearer - why have the parameters been changed all of a sudden without this info being communicated to the chaps offshore, and why were other helicopters being operated to installations quite near us yesterday in the weather conditions which bondu has outlined?

We don't mind being stuck offshore, but we do get miffed when another helicopter passes overhead and lands somewhere else which is clearly experiencing the exact same weather conditions - the fact that it's a different operator to the one who's due to fly to our rig may or may not be relevant....:ugh:

The contract we have indicates that flying can take place as long as the Dacon scoop can be deployed, and no, I wouldn't want to be "saved" by this piece of s:mad:t either.

[[email protected]]

I may be being dull but isn't this what Jigsaw was supposed to provide? - SAR cover for rig transfers when the sea state precluded boat rescue? Or at least a mixture of boats and helos to do the job?

[hands_on123]

I dont think Jigsaw covers Central and Southern North Sea?

[coatimundi]

That said, sometimes the standby boat Captains state at once when they are not happy with the weather. Hats off to them!!

Our skipper was quite clear (and pressure is never applied to him to say otherwise) that his FRC could not be deployed yesterday - but he could use the scoop.

[[email protected]]

handson - then I was being dull then;)

[Noiseboy]

Jigsaw is a BP project, it covers some areas based from Sumburgh and the Miler Platform. Cover is provided for more than just BP platforms I thnk by arrangement but not necessarialy by default.

They will launch for any emergency as requested, but may not be providing standby cover for a specific platform. So if it is Bond flights going to nearby BP platforms then that may be a reason they have flights and others don't.

Although the Miller machine will be likely be in Aberdeen with strong winds offshore due to starting limitations, so that area may be without air cover during those times.

[micraman]

Just to add to the subject,if your shut down limits are say 40 knots(I assume to stop damage if the rotors sail)how do you stand if wind speed is 55 knots and you have to shut down due to mechanical failure

[Colibri49]

If the wind was "clean" coming from the front of the helicopter without having got "chopped up" through a drilling derrick or other superstructure and not curling up over the edge of the helideck after "damming" against the side of the platform, then shutting down in very strong winds would probably be possible without damage. Even so, I would still feel like ducking my head when applying the rotor brake.
If the wind was very turbulent, but I was forced to stop the rotors in an emergency and time permitted, I might ask the deck crew to lash the helicopter to the deck with straps. Then I might get everyone including me to evacuate the helicopter and the helideck before the fuel ran out and the rotors stopped by themselves.
If I was forced to stop the rotors immediately in strong winds and turbulence, I would instruct the deck crew and all personnel, including my fellow pilot, to get clear of the helideck while I stopped the engines and applied the rotor brake. Then I would duck my head very low and hope.
It would surprise me if my statements don't trigger a torrent of different opinions from professional pilots and others, but nothing definite can be written for suggested actions in extreme circumstances. Bear in mind that such happenings are extremely rare.

[Hummingfrog]

I have started and stopped a Wessex in a 70kt wind with absolutely no problem - very little blade sail. The wind was, however, completely laminar with very little gust differential. it is the gust differential that will cause the blades to sail. All the N Sea helicopters I have flown have had a 55kt max wind for shutdown (within a reasonable arc of the nose ie +/- 20 degs). In emergency some helicopter flight manuals advise putting the wind off the nose to try and arrange for the downward sailing blade to pass over the tail before it reaches its lowest point. Which side depends on US or French design.

If you have a mechanical failure then you are committed to shutting down though as one pilot I know can testify in a S61 you will have to duck and then find out how to shut down the engines as the HP cocks have disappeared:eek:

HF

[micraman]

What are the limits for the S76,there blades look low all the time.?????

[lsd]

Max windspeed for releasing the rotor brake is steady 40kts, or gusting to 50kts. For normal operation the rotor brake should not be applied until the rotor speed decreases to between 50% and 60% Nr.

[nbl]

Although it is easy to say 'what if'..
If you are flying ABZ to ESB and the destination rig is in 'wave rescue limits' but the majority of the 250 mile transit is out of limits with no 'Scoop' or anything to rescue you ( apart from SAR ) now what is your decision?
The thoughts on this thread seem to apply only to destination weather, where at least there is some capability - FRC , Scoop - (agreed useless ) 95% of the trip you will have nothing.
I intend to agree with Coatimundi - equal misery or happiness for all.
I am glad I retired.

[C.C.C.]

In emergency some helicopter flight manuals advise putting the wind off the nose to try and arrange for the downward sailing blade to pass over the tail before it reaches its lowest point.Not in a Bell 212 otherwise you will get a tailboom strike. In a 212 it was recommended by our Ops Manual that you put the wind about 30 degrees right of the nose (anti-clockwise rotating blades) and applied forward and right cyclic attempting to keep the disk level, thus the blade would actually be flapping upwards as it past over the tailboom, reducing the risk of a tailboom strike.

[212man]

He said "off the nose" not "on the nose," and the stated which side would vary with US/French type. Much as you have described....;)

[Brian Abraham]

What are the limits for the S76,there blades look low all the time.?????If I recall there were no limits laid down in the RFM, but somewhere there was a note (in RFM?) to let Sikorsky know what your operating experience was. Started up one day on a rig, wind on the nose, after having gone U/S with the wind gusting must have been 50kts or so and I swear one blade came to within 18" of the deck at the 1 o'clock position.

[HeliComparator]

The risk of damage on Super Puma family is more to do with head damage or what happens after rotors have stopped - a rotor blade has been known to sail up to nearly 90 degrees in a gust after shutdown, then fall back down onto droop stop (coning stops having previously been trashed!) whilst pilots are still wondering how to secure the blades.

There have been plenty of cases of keeping the thing running on deck by pumping in fuel, pending an abatement of wind to allow shutdown. Lots of coffee and a shift system required by the pilots!

Interestingly a certain oil company would not allow departure with rotor brake inoperative (its allowed in MEL) in case a/c had to shut down offshore, but were quite happy to allow operation beyond the RFM shutdown limits.

On the subject of rescue, current thinking is that the highest probability of ending up in the water occurs in the vicinity of the destination. Perhaps due to engine failure, perhaps due to crew error, but anyway safety margin is probably less during arrival and departure phase. In the history of the N Sea Super Puma, there has never been a survivable ditching due to a failure en-route (TIGK lightning strike was pretty close to the offshore installation IIRC) so this thinking is borne out by experience, even if perhaps it doesn't seem that logical on first inspection.

HC

[C.C.C.]

Much as you have described....
Not quite.arrange for the downward sailing blade to pass over the tail before it reaches its lowest point.Our technique was to ensure the blade had reached its lowest point prior to travelling over the tailboom.

Shutting an AS332L down in gusting 65kts prior to the 105 rotor brake being fitted got your attention. At least the Aux Hyd pump allowed you to fly the blades past the cockpit. And then the rotor brake slips as you are trying to fit the last blade sock on which has been made a bit small width-wise.

Memories!

[bondu]

Getting back to the thread subject...

As HC states, the current thinking is that an accident will occur near an installation. The PFEER regulations only cover the area around an installation up to 500m. Oil installation operators have to follow PFEER regs to provide a 'good chance of recovery' in the case of a ditching, getting all the survivors to a 'place of safety' within two hours.
There is nothing in current regulations covering the transit from onshore to an offshore installation. Perhaps this should be addressed! Reading the TSB of Canada report on the Cougar S92 accident in 2009, I feel the following recommendation to be rather pertinent!

4.2.2 Safe Ditching and Successful Evacuation
Overwater helicopter operations transporting passengers to and from offshore oil and gas installations occur with the knowledge that an emergency situation may arise requiring a forced landing or ditching. In such circumstances the first priority must be preservation of life and safety of the passengers and crew.

Most helicopters in use to support the global offshore oil and gas industry, including the S-92A, have an emergency flotation system (EFS) which provides adequate ditching stability in "reasonably probable water conditions" of at least sea state 4 WMO and is intended to keep the helicopter upright while occupants escape to the life rafts.

However, helicopters frequently operate over water where the conditions exceed sea state 4 WMO. For instance, in the waters off Newfoundland, statistics from Environment Canada indicate that sea state 4 is exceeded approximately 50% of the time over the course of the entire year, and 83% of the time between December and February. Sea state 6 WMO, by comparison, is exceeded much less frequently; 3.3% over the year and 8.9% between December and February.

Twin-engine helicopters typically have a high center of gravity because of the weight of the engines and the main rotor gearbox located on the cabin roof. Consequently, there is a strong likelihood that these helicopters will capsize after ditching unless they are equipped with an EFS which is appropriate for the prevailing sea state.

When EFS systems do not operate successfully, twin-engine helicopters invariably turn upside down, leading to complete flooding of the cabin and immersion of all doors and windows. Escape is very difficult because all escape routes are submerged and occupants who do not escape from the cabin within a matter of seconds will drown.

Although some steps have been taken in Newfoundland to ensure EFS capability for sea states beyond sea state 4, helicopter crews and passengers in Canada remain at risk where helicopters are operated over sea states exceeding the capability of the EFS.

Therefore, the Board recommends that

Transport Canada prohibit commercial operation of Category A transport helicopters over water when the sea state will not permit safe ditching and successful evacuation.
A11-03

As the 'demonstrated' limit of the floation equipment of the EC225 is 6m, should commercial offshore flights even be dispatched when the sea state is 6m or more? Discuss!!

bondu

[HeliComparator]

should commercial offshore flights even be dispatched when the sea state is 6m or more? Discuss!!


First problem - how do you know what the sea state will be throughout the intended route? AFAIK staying upright is seriously impeded by breaking waves, waves breaking is influenced by all sorts of factors including depth of water, tidal flow etc. So its not just about wave height, it about sea conditions and very hard to predict.

Secondly its surely about probabilities not absolutes? Certification rules for critical items are based around 10^-8 so even the official rules don't guarantee absolute safety (how could they, unless we stayed in the hangar). If you have a look at the history of the industry and see how many survivable ditching there were en-route, then factor in that such a ditching has to happen with sea states out of limits to be catastrophic, I think it would be well within certification safety limits to fly on the odd day with >6m waves.

There is no point in being ultra safe in one particular element of the whole thing, when other areas are less safe (unless it can be done with little or no cost/impact on the operation).

HC

[squib66]

I think it would be well within certification safety limits to fly on the odd day with >6m waves.


So the mitigations would be: HUET + Survival Suits + ELTs + External Liferafts + Prompt SAR?

[micraman]

In the simulator do pilots practice ditching in seas above 6m,thick fog etc or do these come under,has not happend will not happen,heading??

[Redhawk 83]

Is 225 or S92 good for Sea State 6 or 6 metre waves? And if it is based on sea state; which scale Beaufort or Douglas? See table below

The World Meteorological Organization (WHO) sea state code largely adopts the 'wind sea' definition of the Douglas Sea Scale.

WMO Sea State Code Wave Height (meters) Characteristics
0 0 Calm (glassy)
1 0 to 0.1 Calm (rippled)
2 0.1 to 0.5 Smooth (wavelets)
3 0.5 to 1.25 Slight
4 1.25 to 2.5 Moderate
5 2.5 to 4 Rough
6* 4 to 6* Very rough
7 6 to 9 High
8 9 to 14 Very high
9 Over 14 Phenomenal

*Beaufort Scale Sea State 6 is only 3-4 metre Wave Heights.

[Seaweed27]

Sorry I’m a bit late on this thread but I’ve only just joined.


The intent of the PFEER, and other Regulations for Offshore Installations, is that you have to minimise the reasonably foreseeable risks to a level that is as low as is reasonably practicable (ALARP).

The identification of reasonably foreseeable risks is the easy part. Its reasonably foreseeable that a helicopter will ditch near a platform – it’s happened, and its reasonably foreseeable that a helicopter will have to shutdown on the deck in marginal weather – again it’s happened, although not as often as the previous scenario.

The difficult part is weighing up the probability and consequence of such events. That’s where, in my experience, you get the discussions and sometimes there are no absolutely correct answers.

One platform operator and its helicopter contractor could take the view that if the weather is such that the fast rescue craft can’t be launched or the wind over the helideck is such that shutting down or subsequently starting up a helicopter runs the risk of damage to the aircraft then no flying will take place.

Another installation operator and helicopter contractor could take the view that, in similar conditions, the probability of a ditching is so low that they continue to be ALARP due to the ability to use the Dacon Scoop.

Thus you will get diametrically opposite modes of operation in similar weather conditions: which is no great comfort if you are stuck offshore watching someone else’s crew change helicopter overfly you on the way to the beach!

[gasax]

The argument is certainly based around PFEER - but it is complicated by the agreement between the CAA and HSE over juristication. Essentially the HSE have agreed 'hands off' regarding helicopter operations - so there is no published 'good practice' from the HSE on matters like these - and these days it is the published good practice which really sets what ALARP is - not a quantified risk assessement (i.e the frequency or liklihood is very low so its OK).

Reg 17 of PFEER states that 'effective arrangements are made, which include such arrangements with suitable persons beyond the installation, for - ....(b) rescue of persons near the installation; ... etc

So once you start thinking that the Dacon is unlikely to do more than recover bodies - sitting on the platform waiting for slightly better weather seems like a really good idea!

[Helinut]

Just to emphasise a point that gasax made implicitly, the requirement for rescue and recovery is not qualified by ALARP. The reg (17) reads as follows:

"Arrangements for recovery and rescue
17. The duty holder shall ensure that effective arrangements are made, which include such arrangements with suitable persons beyond the installation, for—

(a)recovery of persons following their evacuation or escape from the installation; and
(b)rescue of persons near the installation; and
(c)taking such persons to a place of safety,and

for the purposes of this regulation arrangements shall be regarded as being effective if they secure a good prospect of those persons being recovered, rescued, and taken to a place of safety."

The arrangements have to be "effective" and "secure a good prospect" of success. That is very different from ALARP and a lower legal standard.

It is also certainly true that PFEER does not apply to any helicopter flight away from the installations. Of course, when the worst happens, all available resources would be used, but that is different from being committed to a given standard.

The CAA would not be pleased if the HSE tried to impose standards on their patch.

[bondu]

The CAA would not be pleased if the HSE tried to impose standards on their patch.

It would nice if the CAA imposed any standards and for SRG to actually enforce them. :ugh::ugh:

I once asked a Flt Ops Inspector about enforcement - his reply was that his remit was "to observe and report, not to enforce". So much for the 'regulatory authority'! :ugh::ugh:

bondu :\

[Seaweed27]

The HSE are not trying to impose anything on the CAA. You can down load “How Offshore Helicopter Travel Is Regulated” from the HSE website and it states that the HSE and the CAA have a Memorandum of Understanding regarding the regulation of offshore helicopter travel.

As far as ALARP is concerned that’s how the operators of offshore installations try and judge where to spend their safety-related budget. There is no such thing as absolute safety – nor infinite budgets - so we just have to live with the systems and economic realities as they are.


Having said all that, I’m not an apologist for the Dacon Scoop.

My view is that if its too rough to launch the FRC and the wind across the helideck could potentially damage a helicopter that had to shut down, then we should not be flying.

As the old saying goes, “Its better to be late, than the late!”

[Helinut]

The CAA and HSE certainly have a different view of what a regulator/enforcer should do. Mind you, in the current climate the HSE are being criticised more than the CAA.

My point in raising the two regulators was to make the point that PFEER and the HSE only get involved close to the offshore installation. Beyond 500m from the installation the rules are those of the CAA only, backed up by the Coastguard and the marine SAR setup. Others may get involved, but that is with the roll of the dice, not anythng that can be relied upon.

In terms of what you can practically expect away from the installation, any vessel response is likely to be MUCH slower. Mandatory HUET training, PPE and survival equipment have improved the chances of getting out of the helicopter, so long as the ditching is survivable. Getting rescued to that place of safety remains a really risky process once the sea state prevents use of FRCs, with a substantial delay away from an installation to make matters worse.

The practicalities of rescuing people from the sea mean that once the sea state is too bad to launch (and recover) an FRC from/to a well-found SBV, there isn't really a good prospect of rescuing anyone in the water or a raft (other than if an SAR helicopter is available in a reasonable time).

It will be a major step forward when an effective severe sea state rescue system is available for SBVs, but the laws of physics and hydrodynamics make it a real challenge.