Anne Hope leapt at the opportunity of accompanying a crew on a rotation to one of the many production platforms keeping the wheels of industry lubricated. Here is an account of the process by Mo Jones.
As the price of oil inexorably rises and we feel the effects at the pumps, an unseen result is the level of activity on the North Sea. After many years in the doldrums, offshore oil service industries are once more buoyant. The helicopters transferring personnel to and from the rigs and platforms are working near to capacity. Unless you live around the rim of the North Sea you may never see us but we are out there nevertheless.
From an operational point of view, the waters are divided by the median line, halfway between the coastlines. British operators service the installations west of the line; various Scandinavian outfits the east, ranging from 70 to 290 miles offshore. For many years the Aerospatiale AS 332L "Super Puma" has been the best represented heavy helicopter in the United Kingdom. Although certified by the manufacturer for 24 passengers it is configured on the North Sea for 18 pax. This number reflects avoiding the need for cabin crew, required if more than 19 are carried, but more significantly the bulky survival suits that the passengers wear and the difficulty of evacuating the cabin in an emergency. Average planning weight for male offshore workers is 216 lbs, reflecting their stature. The seats in the helicopter can be folded or removed, allowing the client maximum flexibility on the type of payload. Onshore this is done by the engineers, but away from base the task falls to the pilot. It is one guaranteed to fray fingernails and tempers.
Bristow Helicopters is the longest established of the three major operators offshore in the British sector. As part of the worldwide Bristow Group it operates 33 Super Pumas. Most of them on the North Sea. Many of the adaptations that the aircraft has today have been developed by Bristow since its introduction in the 70's. It has gone from being the flagship to workhorse to classic as the Mike and more recently the Aerospatiale 225 have been commissioned. Things move slowly in the helicopter world as they do with our fixed wing cousins. A multi-million pound machine is decades in the designing.
Aberdeen Airport opens the floodgates at 0630 hrs. The good citizens will not be woken at unreasonable hours by noisy things curdling the porridge. It is a blessing for we helicopter crews who report a minimum of one hour before take off to plan our flights on the basis of weather and client requirements. A machine sat idle earns nothing for the shareholders so helicopters set off on the first wave early in the morning. There is just enough stagger to stream the passengers through the briefing lounges. Upstairs, we study weather on and offshore. Fuel will be carried for the destination and an onshore alternate (in case of a technical fault or a deck problem) and then for the return with an alternate if the weather is less than perfect. We fly in all weathers but limits on wind (above 60 knots rescue at sea becomes hazardous); visibility (it is no longer acceptable to skim the surface to the destination and then scrabble up the legs to the helideck) and thunderstorm activity (composite airframe) can delay or cancel our flights. The client wants a full payload, the pilot wants full fuel. Somewhere between the two will be a compromise. The former never balks when safety is an issue. The power of an aircraft commander over his machine and its contents is ratified by parliament, enshrined by the Air Navigation Order. We come to an accord and when the paperwork is in order, we man the aircraft, aiming to be airborne at the appointed hour.
The Super Puma has an automatic start cycle for each of its two Makila turboshaft jet engines. With the engine speed select in the start gate, the press of a button gets us burning and turning. On high wind days the first engine may be started against the rotor brake but below 30kts there is no need. Engine starts are attentively monitored by both crew and when all checks are completed we can ground taxi to the "hot spot" to pick up the passengers. All stages of the flight are a series of checks, double checks and checking again. Duties are apportioned between the two crew members and critical actions are formally done from a checklist by challenge and response. This system is adopted by airlines worldwide.
While we plan and ready the aircraft, the passengers are checked in and fitted with GoreTex survival suits and insulated liners. Baggage is searched, security is even tighter than regular airline flying, and they will also see a video brief appropriate to their aircraft of the day. We meet when they are brought out to the helicopter, rotors running on the hot-spot. Once the doors are closed they enjoy the bing-bong "Good morning ladies and gentlemen, welcome on board ....". We do make sure they can hear us; someone expecting to go to the Shearwater will often pipe up if he is told he is being taken to the Cormorant. We hope. Briefing done, we call on ramp and the air traffic ground frequencies for taxy. The Bristow apron is a three minute taxy from the holding point, during which time we perform instrument checks which require us to be moving. At peak times, such as early morning, we can wait in a queue for 20 minutes for take off. This can be critical on fuel so holding time is planned in at the captain's discretion.
Aberdeen's runway 16/34 is the only one licensed for fixed wing operations, but helicopters can use the two shorter cross runways. We are often asked why we need a runway at all when we are a helicopter. It all boils down to performance. The customer on any flight reasonably expects the safest possible carriage and we operate to performance Class One. This guarantees that in the unlikely event of failure of a critical power unit (an engine) the aircraft can either reject back onto the runway without damage or continue flight. Thus we fly formal "profiles". Our routine "Procedure 2" profile is a near level acceleration to take off safety speed (Vtoss) followed by a climb out at Vy, best rate of climb. At a point in the first segment we will reach Critical Decision Time - CDT. This is worked out before flight and depends on the weight, wind, temperature and pressure of the day. Before that point, we may not be flying fast enough to fly away and avoid obstacles if an engine fails, so we will reject, ie return onto the runway. After CDT we can safely fly away. When there is insufficient runway left ahead to reject, then we are committed. Of course if the runway is short these two points are coincident. This formality ensures that the non handling pilot is in no doubt as to what will happen if there is a problem.
Safely away from the ground we make after take off checks and climb up to 3000 feet. Our outbound track to the destination is dependent on the track structure, a series of radials 3 degrees apart based on the ADN VOR. This is a radio beacon seven miles north of the field. With so much traffic in the area it is organised into the Helicopter Main Route structure above 1500'. Outbound radials are six degrees apart, 065, 071 degrees etc, flown at 3000' and inbound ones between them, 068, 074 etc flown at 2000'. This gives traffic a vertical and horizontal separation in theory. At some stage you need to leave the HMR to go direct to your deck and there will be machines transiting between decks, climbing and descending or making radar approaches, so it takes good spatial awareness to keep track of who else is likely to be a possible conflict. Radar coverage is provided by Aberdeen out to 80 miles and flight information beyond but there are areas of poor coverage and black holes in the rebroadcast system here and there.
After the initial cruise check is completed we cannot rest on our laurels. The fuel on board must be rechecked. We will perform routine performance checks on the engines. As soon as we are in radio range of the destination we will contact them to check their weather. Atmospheric conditions are the biggest influence on how we conduct our flight. Whether or not we can see out of the window, we usually fly Instrument Flight Rules -IFR. The other option is VFR or Visual Flight Rules. These would apply to flights where we take all responsibility for seeing and avoiding and the destination and surface are continuously visible. This we can rarely guarantee and IFR affords us a degree of protection from other IFR traffic. This service is provided by Air Traffic Control. If we cannot see all about us, the conditions are IMC. Instrument Meteorological Conditions. A bright clear day would be VMC, Visual Meteorological Conditions, but we would still opt for IFR for control and procedural services. Simple really. The perception of many is that The North Sea is in a state of tempest all the time and that our lives hang by a thread and aren't we terribly brave. The reality is that weather patterns are not that different to onshore. It is just a little windier. And maybe foggy a bit more often. OK, yes we are terribly brave.
Helicopters perform best with a bit of wind as it takes a lot of power to hover in none. If there is some wind over the disc when we are stationary, effectively we are in forward flight so have more power in hand. Wind affects how fast we fly relative to the ground and thus where we might choose as an onshore alternate. For instance, strong westerlies will give us best diversions in Norway. Physically we can fly in any wind you like but in practice when the offshore winds exceed 60 kts, rescue in a ditching situation is extremely hazardous for all concerned so flying is suspended. To put this in perspective, storm force 10 on the Beaufort Scale is winds between 48 and 55 kts and is seldom experienced inland; trees are uprooted and considerable damage occurs. At sea the scale quotes "Very high waves with long overhanging crests. The resulting foam, in great patches, is blown along the direction of the wind. On the whole the surface of the sea takes a white appearance." Passengers disembarking a helicopter in these winds would be at serious risk of being blown over the edge of the helideck. Conditions that are best avoided. When it comes to visibility we fly to the same standards as our fixed wing colleagues onshore and we are limited by the published minima for that airport for our class of machine, ie slow. Offshore it is a different matter.
|
