Clearly Swamp76 is not coming over the parapet so I will take this further.
Just a brief word on the CAT A landing procedures; there appears to be little distinction made between onshore and offshore procedures. The guidance in AC 29-2C still makes the statement that “a safe landing should be possible in case of an engine failure at any point before or after LDP”. Although an offset approach and drop down are now permitted, the inference (of this statement) that there is always a flat-top landing surface to which a non-turning landing approach can always be made, does not reflect restricted approach directions often present at offshore drilling rigs and larger platforms.
Hence, there will be occasions when an OEI transit and landing will not be possible (within crosswind limits). There is little benefit for manufacturers in providing a late and offset LDP because, if the whole of the procedure has to be able to be flown OEI, it will (for aircraft other than the likes of the AW139) reduce the landing masses in the Flight Manual. Worse than that, and bearing in mind the subject of this thread, provision of LDPs set at speeds which ensure that it has to be placed well back from the helideck and at low approach angles requiring a long and continuous OEI transit, give the message that straight-in approaches are not only inevitable but safe.
It is imperative to understand what conditions our consideration of the approach and landing manoeuvre. In my opinion, the main hazards (along with escalation and barriers are):
Hazard:
Collision with obstacles on and around the helideck.
Escalating factors:
Size of helideck and proximity of obstacles.
Barriers (to prevent release of hazard):
Accurate markings provided by the Touch Down and Positioning Marker (TDPM = bum-line);
Absence of the need to manoeuvre when on the helideck;
Approach paths which permit the Best Field of View (FOV) of the TDPM;
Understanding by pilots of the predominant hazards.
Hazard:
Inability to maintain safe flight path on approach and landing.
Escalating factors:
Loss of view of TDPM resulting from poor FOV;
Engine failure on approach;
Turbulence that prevents constant attitude approaches.
Barriers:
An approach path that permits the TDPM to be kept in field of view;
An approach path which retains go-around option until the committal point (CP) has been achieved;
The provision of a CP at the point where a OEI landing manoeuvre to the TDPM can always be achieved;
(Where possible) a landing mass which permits drop-down clear of sea until CP is achieved (at the moment this is achieved: when there is wind – the mean wind in the Northern North Sea is 20kts, the mean temperature is 10ºC and it rarely goes above 20º; or at low landing masses).
There are more but that will suffice for the time being.
There are compensatory conditioning factors which apply to operations in Europe (and in a number of other operating areas):
Two pilots are usually carried (so the obstacles can always be placed on the best side);
Two-way fuel is carried because offshore operations require an onshore alternate;
There is no stigma attached to a go-around and return to base.
From this brief analysis, we can see that any profile that is used must be optimised for the normal – i.e. the thousands of approaches that are conducted every day with AEO. As the main hazard (and the one which is seen in incidents and accidents most often) is striking an obstacle on or around the helideck, the profile should be one where the pilot-flying can keep all obstacles in view, with the TDPM as a clear aiming point – i.e. a sidestep manoeuvre keeping the helicopter into wind with the TDPM in the oblique or side window.
Further, because there is a risk (albeit a small one) of an engine failure with potentially catastrophic consequences, the exposed period - from the point where a go-around is no longer possible and the CP - should be minimised (and reduced to zero if possible). In addition, to avoid a complex manoeuvre, the approach path should be offset from the helideck such that a straight ahead go-around manoeuvre is possible without an avoiding turn.
As was stated in the analysis above, under the conditions where return fuel is carried, no OEI landing on the deck has to be made unless the CP has been reached; all approaches will therefore be made in the knowledge that an OEI recovery to a land base will be possible.
Jim