Time taken to turn around offshore

[Locktopus]

Hi all,
I was wondering if any of you could help with a piece of information I am looking for. I am doing an analysis of evacuation times in an emergency offshore (north sea).

My questions are, in a developing emergency down manning scenario:
1) How long would it take to turn around a helicopter, i.e. from landing to pick up crew then take off?
2) What is the minimum time gap between one helicopter taking off and the next one landing?

If possible, would be good to base it on Sikorsky S-92 in offshore configuration with 19 crew, pilot and co-pilot.

Would really appreciate your thoughts. I know this is likely to be a bit of an estimate but there doesn't appear to be any hard data on this anywhere and although I have been offshore before I am reluctant to base on my own minimal experience.

Thanks in advance! :)

[GoodGrief]

My questions are, in a developing emergency down manning scenario:
1) How long would it take to turn around a helicopter, i.e. from landing to pick up crew then take off?
2) What is the minimum time gap between one helicopter taking off and the next one landing? I don't know where this goes, but anyway.
In the shuttling scenario with absolutely helicopter-inexperienced people, some have never seen a helicopter in their life before, I have a turnaround time of usually 45 seconds which include disembarking of 5 to 6 pax, unloading their luggage, hot refuelling, embarking and strapping in 5 to 6 new pax and loading their baggage.
When things go very slow I have a minute to a minute and ten.
Now that's in a 407.

Boarding 16 experienced pax in an emergency shouldn't be much more than that. Especially when the machine comes in empty not unloading anybody.

2. I'd say about 20 seconds.

[Bravo73]

I have a turnaround time of usually 45 seconds which include disembarking of 5 to 6 pax, unloading their luggage, hot refuelling, embarking and strapping in 5 to 6 new pax and loading their baggage.


You can do all of that, including refuelling, within 45 seconds? Wow. :sad:


To the OP, the aircraft will have to land on and landing checks completed. Lifejackets would then have to be unloaded by the deck crew then put on by the passengers. These passengers would then have to be loaded and secured before take off. Conservatively, this whole process will take at least 5 minutes, maybe nearer to 10 minutes for a deck crew and passengers who aren't very well practised. (3-5 minutes is an average turnaround time for a smaller, very experienced and practised NUI crew).

Once that helicopter has cleared the deck, the next helicopter can be given 'deck available' by the HLO. So, depending how far out on the approach the next aircraft is, anywhere from 30 seconds to several minutes between t/o and landing. A sensible estimate would be 1 - 2 minutes.

[terminus mos]

We take 20 minutes for a disembark, 800 lit refuel, embark, bags etc. on a crew change for a 92 or 225. It is a bit helideck crew dependent.

We schedule 30 mins between aircraft departures from base so as one lifts offshore the next is 5-10 mins out when we do cyclone evacuations of a MODU.

Gap between landings dependent on wake turbulence but wind in the NS dissipates it within 30 seconds or so. However, in reality, the likelihood of having aircraft queued up one behind the other is low.

[HeliComparator]

Yes a big consumer of time is refuelling and baggage. In a serious emergency the latter is surely dispensed with, the former will depend on the range etc, but it might be possible to refuel at a nearby installation once the pax are off the rig.

Lifejackets? Well if the rig was on fire, I think life jackets can be dispensed with, although no doubt there will be some jobsworth who says "rules is rules" whilst the flesh is charring!

For a normal turnaround, as TM says 20 mins is a good figure, so from that you can subtract elements to whatever the degree of urgency dictates.

[Locktopus]

Hi again

Thanks for your help. I am going to assume the crew will already have their survival suits on as they bring them to muster and soon as word goes up that they are going to evacuate they will all have them on.
All crew will have BOSIET training and probably quite used to helicopter transfers.
I will assume they do not refuel before TO but if they need to they can stop at one of the other helidecks nearby (there should be plenty of options in the North Sea).
So I think the best estimate would be 3-5 minutes to load and then minimum 2 minutes until the next helicopter lands. If we assume 3-4 helicopters are shuttling to other rigs nearby then it should be feasible to downman fairly rapidly although I guess weather will be a big factor (in which case, there are lifeboats).

Any other thoughts or comments do let me know. You've been most helpful!

[212man]

....with 19 crew, pilot and co-pilot.


Doesn't leave much space for the pax :E

[[email protected]]

Is that '45 seconds' special African time, a bit like an engineer's 'it'll be ready in 30 minutes'? ;)

[GoodGrief]

Is that '45 seconds' special African time, a bit like an engineer's 'it'll be ready in 30 minutes'? ;)
How I hate those...

Nope.;)
It's adding 25 to 30 liters to make the trip up the mountain and back down with max. load at 15000+ft DA.
Max fuel = 120lbs on the clock, roundtrip time = 9.5 to 11 minutes.

[Fareastdriver]

Typhoon Evacuations were commonplace in the Far East where up to seventeen installations had to be evacuated over two days by six 332s.
The aircraft would arrive, empty and not requiring fuel. By the main door would be stowed 19 lifejackets for the next lift because the rigs already had a set to fit their inbound.

After landing one pilot would open the main door and the deck crew would send the pax up as the removed the second set of lifejackets. Loading, headcount and baggage bay check would take about a minute and the walkaround, pre-take offs and lifting another minute.

All-in-all about 2.30 to 3.00 minutes.

The other extreme is mentioned by terminus mos, a rig off Barrow in Australia.

Land on. Pilot climbs out and opens the door. Signals to the deck crew they may approach. Passengers led to the exit. Baggage trolley, (by the exit) unsecured from the deck and pulled over to the luggage bay. Luggage loaded and then the trolley is pulled over to the exit and unloaded. The trolley then returned to parking position and secured to the deck.

So far, 10 minutes.

The helicopter now definitely needs to refuel.

Stat up pump and call pilot down to show him a sample drowned in a bucket. When that is approved commence untangling the refuelling hose from the lower deck floor. Lift it up to helideck level and position by refuelling point. Wait until three deck crew have donned fireproof clothing and holding fire extinguishers leaving one to monitor the fuelling process.

After refuel recover hose to the lower deck. When that is complete take two further samples to be checked by the pilot. Then the deck crew disrobe from their silver suits.

Call the passengers to the lower deck. They pass their luggage up to the helideck where the deck crew are releasing the baggage trolley from the deck. Baggage loaded onto trolley and taken to the aircraft. When the baggage is loaded and the trolley secured the passengers are called up to the aircraft. The HLO then checks their names against the manifest as they pass him.

Eventually they are loaded and the aircraft gets airborne just before it needs refuelling again.

You couldn't make it up. H & S gone mad; total time about twenty five minutes.

[albatross]

Arriving with 0 pax aboard and 19 jackets no refuel needed
I think a 10 minute wheels on to wheels off would be a reasonable planning number for a 92 and 15 for a 225 if bags are carried.
10 minutes for both with no bags. In a crisis situation I don't think bags are necessary.
Anything less would be overoptimistic for planning.
Just my 2 cents worth.
I don't think we will be cleared for landing on any burning rigs.

[nowherespecial]

19 pax on and off with experienced crew for L2 (and most likely 225 therefore) has historically been 10 mins and totally agree it depends mostly on baggage and how much refuelling (if any) which will stretch this time by at least 5 mins owing to the 'convenience' of onloading bags.

If you add life threatening danger, i suspect a huge chunk to come off though :)

The ERPs should reflect a de-manning procedure though, it is a very common risk which the operators address. Check in there. Would be interested to hear what they say. I'll check mine now.

[diginagain]

Both ASET and Falck run Management of Major Emergencies courses for rig management, and may be able to provide the OP with information.

[Bravo73]

It's adding 25 to 30 liters to make the trip up the mountain and back down with max. load at 15000+ft DA.

Ah, rightio. Not many mountains offshore...

[Bravo73]

I don't think we will be cleared for landing on any burning rigs.

My thoughts exactly. Why potentially add a couple more bodies and a $20m aircraft to the casualty list?

If the helideck, or the surrounding area, is already on fire, it sounds like any potential evacuees will have to be fished out of the water by a SAR aircraft.

[Self loading bear]

The rig, the rig , the rig is on fire (add your own music)

Luckily rig fire is not the most occurent reason to evacuate.
I recall some collisons between semi-subs and a supplier, making them less stable.

On the Dutch side i remember a freighter with 1 engine inoperable. It was the only engine.
The ship came a drift in a storm and was on collison course with the accommodation rig Seafox 2. (200 POB)
Although they had some hours response time, It was at night and initially only 2 choppers could be made available. As the ship drifted by at 500 meter, we might probably never know if 2 choppers would have been enough if complete evacuation would have been required.
(Somebody out there with more knowledge of this case?)

As long as you have only 2 helis available the turn around time is hardly an issue.
They will alternate between the danger and safe rig.
Other posters have already shown turn around time is probably shorter than the flight time.
So up to 4 helis will not make turn around time critical.
(2 in the air, 1 on danger and 1 on safe deck)
If one of the helis would have to refuel it will be done on the safe rig.
So that could hold up the other aircraft.

So look at
1) number of aircraft that can be made available,
2) distance to nearest safe rig(s) (with re-fueling)

If you have to pull it off by saving 1 minute on deck, I think it is an unsafe operation of the rig operator

SLB

[John Eacott]

148 flown from oil platform after power outage (http://www.scotsman.com/news/scotland/top-stories/148-flown-from-oil-platform-after-power-outage-1-3515932)

That would have taken a bit of flying time: was anyone here involved?

NEARLY 150 oil workers had to be flown off a North Sea platform after a power cut left it in darkness.

A total of 148 non-essential rig personnel were flown off oil giant Shell’s Nelson platform by helicopter on Tuesday.

And one of the helicopters making the transfer to an offshore accommodation unit had to make an unscheduled landing on another oil platform after a cockpit light came on.

A Shell spokeswoman yesterday described the rig incident as a “non-emergency” situation.

She said: “Shell UK Limited can confirm that there was a power outage on the Nelson platform, which is located approximately 124 miles east north-east of Aberdeen.

“Nelson was shut down for maintenance at the time and was not producing oil or gas.

“Work to restore main power on the platform continues with essential staff on board.

“As a precaution a non-emergency operation to remove staff to the nearby Borgholm Dolphin flotel was carried out yesterday.

“Personnel will be transported back to the Nelson platform or to Aberdeen over the next 48 hours as appropriate. There are no reports of any injuries as a result of this outage.

“The relevant authorities have been informed.”

Only 19 of the the 167 staff on board were left on the platform following the downmanning.

The platform was not producing oil or gas at the time of the blackout.

CHC confirmed that one of their helicopters was diverted to an Apache-operated platform in the Forties field before completing the passenger transfer.

It is understood it was not an emergency situation.

A spokeswoman for helicopter firm CHC said: “A helicopter was diverted and landed safely on the Forties Delta platform after a cockpit light was observed by the pilot.”

The power outage took place on the Nelson platform, 124 miles north east of Aberdeen, just before 6am on Tuesday.

The rig was undergoing planned maintenance when there was a loss of power at 5.50am.

RMT regional organiser Jake Molloy said yesterday that Shell had done “the right thing” in the circumstances.

He said: “Shell contacted us and gave us a briefing on this - a pre-cautionary downmanning due to a lack of power.

“This is what should be done in those circumstances.

“If there is no power for the life support services - air conditioning, lighting and such - you have got to put the guys to a place of safety - in this case the Borgholm Dolphin.

“Shell said it was hoping to get the platform up and running again as soon as possible.

“You can’t leave people on installations when you have power outages.”

by ALAN SHIELDS

http://www.scotsman.com/webimage/1.3515931.1408556342!/image/1141282921.jpg_gen/derivatives/articleImgDeriv_628px/1141282921.jpg

[Self loading bear]

Locktopus,
I hope it wasn’t you, doing a bit of testing of your emergency case?:=
http://www.offshoreenergytoday.com/premier-evacuates-workers-from-balmoral/ (http://www.offshoreenergytoday.com/premier-evacuates-workers-from-balmoral/)
http://www.offshoreenergytoday.com/shell-evacuates-north-sea-platform-after-power-supply-problems/ (http://www.offshoreenergytoday.com/shell-evacuates-north-sea-platform-after-power-supply-problems/)
The last one is also covered in another thread North Sea News post 301.
Like John Eacott said in that post: It would be interesting if somebody could shed some light over these evacuations: initial response time, number of heli’s, turnaround time, could they do the same at night? etc.
Cheers SLB

[Locktopus]

Very interesting, nothing to do with me! Like you said, I would love to know how long it took. My estimate (based on this thread) would be about 3 hours.

Thanks!

[Burr Styers]

Hi Lokto,

I'm curious. Which company or organisation do you work for, what is the reason for your interest, and given the wide range of answers that you have received, who is going to credited with whatever data you use, and where and how is this unverifiable information gleaned from a public forum going to be presented. Just curious, that all.

Rgds

BS