Fuel & the North Sea

[bayou06]

How do the oil operators support the aircraft with fuel in the North Sea? Do they have fuel on the drilling rigs/vessels or dedicated fuel stations on certain platforms?

I was under the impression that a good deal of the time that flying in the North Sea was done under IFR conditions. Are you typically carrying round trip fuel or enough fuel for your destination, fuel stop and reserve?

I fly S76s in the GOM and weather dictates our fuel and flight profiles (like everywhere else :)) Flying IFR limits our load due to the additional fuel required. Many of the oil operators will have us wait til VFR weather so that won't have to bump PAX and make more trips. What is the thought process in the North Sea? Thanks.

[HeliComparator]

In the northern part of the North Sea (out of Aberdeen and Shetland Islands) most - nearly all - offshore installations (platforms and rigs) have a fuel installation - fuel is taken out by ship.

For the older types (AS332L etc) refuelling offshore is fairly common as if the customer wants a big load (which they usually do!) we would take enough fuel for destination plus alternate, but perhaps not enough to allow for the time running on deck (maybe 20 minutes these days) nor enough to keep the wife and kids secure. If the weather is mediocre at base, we may be able to use base as the alternate from the offshore destination, but would need another alternate when base is the destination (we have a "coastal aerodromes" thing that means we don't need an alternate for IFR arrival at base if the weather is reasonable.

The new generation aircraft (225 and 92) would normally be able to do the round trip without refuelling unless its a long one up to the Shetland Basin / West of Shetland.

As you say, most flying is IFR so if the client waited for a VFR day they would be waiting a long time. Trips tend to go ahead regardless of the weather/payload, though perhaps that's because with full fuel the payload is still not too bad (and not restricted on the new types). Trips are only held if it looks unlikely that the flight will get in to the rig (fog), its too windy, or if there are no alternates etc

HC

[zalt]

bayou06
So if you don't have onshore diversionary fuel in a GOM 76 , you ditch if you lose an engine right?

[bayou06]

Why would you depart if you didn't have weather or fuel for an alternate in the first place?

[bayou06]

Heli,

Interesting. You folks in the North Sea plan with fuel as primary factor and load as a secondary factor. I understand why with the weather you face there. In the GOM, the weather is VFR enough that the oil operators will wait. They would rather you fly out with two more PAX a few hours later. And, generally this works out. Obviously we have two very different weather patterns. Thanks.

[BaronG]

The Southern UK bases (Humberside, North Denes/Norwich and Blackpool) use S76s and Dauphins.

Those bases have a slightly different problem in that, with IFR fuel on board, the available payload is greatly restricted (possibly half or more of the payload in extreme cases). If we "really need" IFR fuel then often the cost is too high and the client will suspend the flight unless it is urgent/or has a small payload.

The Ops Manual gives the minima for VFR/VMC planning and those are pretty low anyway - it is a rare day that you can't get away with VFR fuel loads (even though the trip is flown IFR and possibly in IMC enroute). On the days you can't plan VFR, for IFR you need an alternate outbound to the Platform (often the base airfield) and on the way back, you need fuel to your base airfield and for an alternate (while not prohibited, departing from base when the actual WX is less than approach mins is of course not recommended, and requires yet more fuel for takeoff alternates thus further limiting available payload).

In certain circumstances this can lead to a slightly odd situation that you need less fuel on lift at your base to start the flight than you do when you lift from the offshore platform inbound. If there's fuel at the offshore destination, this can at least make the flight possible, but generally still unlikely due to the reduced payloads.

Another concern is the possibility of a diversion - with so few airframes available, having one land away, with the associated time and cost implications of having it unusable, paying for hotels/additional ground transport and getting it back isn't usually an option.

BG.

[Gomer Pylot]

With the A++ and C+, as well as the 412, there is no need to ditch if OEI, you can land on a platform. In the GOM, the alternate can be either a designated platform or an airport on land, depending on the situation. When you're going 150NM+ one way outbound, it gets difficult to use onshore alternates with any reasonable payload. The S92s use an onshore alternate all the time, due to customer requirements.

[bayou06]

You situation in the Southern UK bases track very similarly with what we face in the GOM. I fly for Air Log and currently our main medium lift is the S76s, so we face nearly the same planning factors. The company is forecasting S92s and EC332Ls in the future. The exception is with our B214STs. Those beasts generally have ample fuel for most deep IFR trips. They're not real fast, but they can carry a bunch of folks with lots of fuel.

[Hippolite]

Gomer

Are you guys still flying one way fuel on S76A++s, C+s and 412s?

[Gomer Pylot]

Of course.

[Hippolite]

Gomer

I thought that most of the oil companies had stopped one way fuel operations but obviously commercial expediency still rules in the GOM.

I don't know about others pilots but a Max weight take off from a shore base in an A++ followed by a 150 mile sector with a 700lb fuel burn off and a landing weight of around 10100 lbs single engine on a helideck would not be my ideal way to spend a day. The alternative of a ditching wouldn't be much more appealing.

Maybe I am just a chicken....the Safety Case would make good reading...

[malabo]

A Safety Case could have interesting results. There are enough operations in the GOM to generate reliable statistics. Like how many times in one-way fuel situations has a multi-engine aircraft landed single-engine on a rig. Maybe as many times as a North Sea helicopter has ditched with both engines still running (sorry, couldn't help it).

Let's see, first of all you are only concerned about the trip out, not the trip back, so that cuts your exposure time in half. Then at least to halfway out you'd still have enough fuel to get back. Add in the reserve (45 min?), and in no wind conditions you could get even closer to the rig, lose an engine and still make it back to shore. The exposure time gets smaller and smaller. The farther out you go the more fuel burned and the lighter the aircraft, making the landing on the rig easier.

You'd have to compare apples to apples on engine failures, and not count voluntary shutdowns that are probably more common in the North Sea than in the GOM.

If the only way to service a deep-water rig was one-way, we'd probably select helicopter with better performance (C++, S92, 332L2, 225, 139) or perform some statistical CL2e black magic and go anyway. There are other parts of the offshore world with one-way fuel (Australia?).

Malabo

[Brian Abraham]

The Esso operation in Bass Strait (Australia, VFR operation) had an ops manual requirement and a regulators supplement to the flight manual which required an on shore field to be available for all off shore operations to cater for the engine out case. No one paid any attention to the requirement though and the company reasoning was that the chance of being put into a situation which might require such an out was infinitely small. (Risk management matrix that they were so fond of I guess). This resulted in frequently having to shut down on rigs because of weather closing in. I should add that we didn't bother with weather reports either, so no pre planning as to what might be expected. Worlds best practice we were told.

[RedWhite&Blue]

BaronG
You say that in the SNS... "The Ops Manual gives the minima for VFR/VMC planning and those are pretty low anyway - it is a rare day that you can't get away with VFR fuel loads (even though the trip is flown IFR and possibly in IMC enroute). On the days you can't plan VFR, for IFR you need an alternate outbound to the Platform (often the base airfield) and on the way back, you need fuel to your base airfield and for an alternate..."
I thought that even for a VFR fuel plan you need to specify an alternate to an offshore destination, and to carry the requisite fuel. What do you do if you haven't, and you can't get 'three greens' for example when you arrrive offshore?
Also is it not the case that if you operate to a 'coastal aerodrome' you can waive the requirement, under certain weather circumstances to carry detination alternate fuel, ie.better than 600ft cloud base and 4000m viz eta +/-1 hour by day and 1200ft/5000m by night at the destination, even when flying under an IFR flight plan?
It seems we carry IFR fuel more often than rarely in our neck of the SNS.
Red

[212man]

Bayou6, to summarise (for N. Sea):

1. All offshore destinations require an alternate

2. Depending on the range and the weather, the alternate may be the departure aerodrome. Typically, the further the 'rig' the more likely it is the alternate is going to be another aerodrome, and frequently will be in another country (Norway, Denmark, Holland for UK departures)

3. JAR Ops (and ICAO annex 6) does not allow offshore alternates for payload enhancement i.e. where a land alternate could have been used with more fuel. This means even if the land aerodrome is below minima and therefore stopping the flight. There are no N. Sea destinations with no land alternates available.

4. The alternate criteria are RVR+400m and cloud ceiling +200 ft for the approach in use (so typically 900m and 400 ft)

5. The destination minima for coastal aerodromes are relaxed from the normal VFR minimums to 600 ft/ 4km by day, 1200 ft/ 5km at night i.e. no alternate required if at or in excess of those minimums. If below, then an alternate required, see item 4.

6. If fuel available on the 'rig' then fuel carried for destination plus alternate. If return leg requires an alternate too, and no fuel on rig, then fuel carried is destantion plus alternate plus alternate for return destination (plus MLF, contingency, approach etc)

7. There is the apparent anomaly that your departure aerodrome could satisfy the requirements of an alternate, and therefore round trip fuel be sufficient, but that having landed offshore, you will need more fuel because what was your alternate is now your destination, and it is less than 6/4, 12/5 and so requires an alternate.

8. There is no approach ban for a rig radar approach, so technically you could depart for a 'rig' you are unlikely to see. However, the client is likely to hold the flight, especially if the alternate is in a foreign country and the crew will land with insufficient duty time to come home!

9. Departure aerodromes require an alternate within 60 minutes AOE cruise. Typically this will be the departure itself, but departure minimums (150 m RVR) are generally below landing minimums (500m RVR), so a real alternate may be required. This causes fun and games when the East coast of Scotland is fogged in, and much crew room discussion about the whys and wherefores of minimums!

10. In Brunei it is hot and sunny and we fly 40 nm to rigs (with no fuel) in a 140 kt aircraft with a 5000 lb fuel tank: problem solved!

[BaronG]

RW&B

I thought that even for a VFR fuel plan you need to specify an alternate to an offshore destination, and to carry the requisite fuel. What do you do if you haven't, and you can't get 'three greens' for example when you arrrive offshore?

That's right, I didn't make that very clear in my post.

As for the Coastal Aerodrome stuff, that's in the Ops Manual but the "criteria" for Coastal Aerodrome designation isn't entirely obvious :)

BG

[helimutt]

So go on then, specify 'coastal aerodromes', as used by CHC. Bet you can't think of many.!! :hmm:

[Hummingfrog]

CHC- Scotia coastal airfields - Aberdeen and - oh there aren't any more even though Blackpool and N Denes are nearer the sea than Aberdeen. It is all down to cost due to extra weather resources needed for a coastal airfield.

HF

[zebedee]

Hummingfrog
You are right that it is cost, but the "extra weather resources" boil down to just the airport in question publishing a TREND report. If it does, then "coastal airport" rules apply, if not, nix.
Zeb