Interpreting the orientation of the H letter to land on helidecks
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Interpreting the orientation of the H letter to land on helidecks
Although landing with the pilot seat on top of the inner edge of the aiming circle ensures that a helicopter with maximum dimension D is clear from obstacles while on deck, not all conceivable landing paths to get there are safe. Without bringing the relative wind into the equation, safe landing paths would be those where the helicopter moves towards the aiming circle from positions where it is entirely within the boundaries of the obstacle-free sector (OFS).
Although the chevron provides a visual cues about the OFS, the chevron is not a reference for the flight crew, but for the HLO. What, then, could be a source of OFS-related visual cues for the flight crew? That would be orientation of the H, of which the cross bar is in line with the bisector of the chevron. Although the H won't provide precise visual cues about the boundaries of the OFS, at least it helps to know what is the helideck (half) sector where any landing path can be performed wiht the helicopter entirely within the the OFS.
Therefore, it seems to me that properly interpreting the orientation and relative position of the H is safety-critical skill for offshore helicopter pilots.
I would much appreciate to know your thoughts about that.
Although the chevron provides a visual cues about the OFS, the chevron is not a reference for the flight crew, but for the HLO. What, then, could be a source of OFS-related visual cues for the flight crew? That would be orientation of the H, of which the cross bar is in line with the bisector of the chevron. Although the H won't provide precise visual cues about the boundaries of the OFS, at least it helps to know what is the helideck (half) sector where any landing path can be performed wiht the helicopter entirely within the the OFS.
Therefore, it seems to me that properly interpreting the orientation and relative position of the H is safety-critical skill for offshore helicopter pilots.
I would much appreciate to know your thoughts about that.
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Helideck H
The crossbar of the H bisects the OFS, which means the parallel bars of the H point away from any obsticle on the Helideck. All information can be found online in CAP437.
There is a website Thought Process Ltd Global Aviation Industry Tailored Training Videos where you can sign up for an online course on CAP437 I learnt lots I thought I knew! Worth it in my opinion.
You learn something new every day! Who knew that the cross bar of the H is in line with the bisector of the OFS chevron?
Although I must confess that, having only completed 10+ years flying offshore with however many ‘000s of landings that equates to without ever having known that, I am struggling with the concept that this piece of information is “safety critical“.
I just make sure there’s nothing sticking up between me and where I want to land.
Although I must confess that, having only completed 10+ years flying offshore with however many ‘000s of landings that equates to without ever having known that, I am struggling with the concept that this piece of information is “safety critical“.
I just make sure there’s nothing sticking up between me and where I want to land.
Not sure if it relevant or not, but the latest version of CAP437 has the centre of the H back in the middle of the deck. For years it was offset by 0.1 D. Thik it might be associated with the illuminated H and Aiming Circle.
There is not much that could be added to 'fermrib's' description although this statement merits a comment:
Clearly the whole helideck area (TLOF, FATO and OFS) are clear of obstacles; the OFS should be 210 degrees and not, as stated, 'half'.
As has often been shown on PPRune, not all offshore pilots know, or understand, the logic of the helideck markings. One of our most experienced members has just demonstrated that.
To answer 'fermrib's' question, the orientation and markings of the helideck should be known to the pilot before the sortie starts. Those of us who have the experience of many offshore landings will know that the cues to the approach direction and the final path to the helideck will not be the on-deck markings but general cues. With this in mind, pilot must be aware that the critical marking is the Touchdown/Positioning Marking (TD/PM) which will ensure that the helicopter is free of obstacles when the helicopter is placed correctly (as you have stated).
The modern trend, even for PC1 heliports (helipads), is for the landing surface (TLOF) to be less than the overall dimensions of the helicopter (the 'D'). Because of this, it is critical that designers ensure that the FATO is completely free of obstacles as required by Annex 14 and CAP 437 (which will soon become the basis for the ICAO helideck guidance) and pilots understand the relevance of, and correctly position in accordance with, the TD/PM.
Jim
Although the H won't provide precise visual cues about the boundaries of the OFS, at least it helps to know what is the helideck (half) sector where any landing path can be performed with the helicopter entirely within the the OFS.
As has often been shown on PPRune, not all offshore pilots know, or understand, the logic of the helideck markings. One of our most experienced members has just demonstrated that.
To answer 'fermrib's' question, the orientation and markings of the helideck should be known to the pilot before the sortie starts. Those of us who have the experience of many offshore landings will know that the cues to the approach direction and the final path to the helideck will not be the on-deck markings but general cues. With this in mind, pilot must be aware that the critical marking is the Touchdown/Positioning Marking (TD/PM) which will ensure that the helicopter is free of obstacles when the helicopter is placed correctly (as you have stated).
The modern trend, even for PC1 heliports (helipads), is for the landing surface (TLOF) to be less than the overall dimensions of the helicopter (the 'D'). Because of this, it is critical that designers ensure that the FATO is completely free of obstacles as required by Annex 14 and CAP 437 (which will soon become the basis for the ICAO helideck guidance) and pilots understand the relevance of, and correctly position in accordance with, the TD/PM.
Jim
ICAO Annex 14 5.2.2.5 A heliport identification marking shall be oriented with the cross arm of the H at right angles to the preferred final
approach direction. For a helideck the cross arm shall be on or parallel to the bisector of the obstacle-free sector.
approach direction. For a helideck the cross arm shall be on or parallel to the bisector of the obstacle-free sector.
Shore side I wouldn't bet on it so much as some of the markings could have been installed by the "who knew" brigade as posted here.
Making sure that there are no bits sticking up between you and the pad has served well so far!
That’s pretty scary - 1000s of helideck landings and you’re not aware of what information the deck markings can give you........
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I thought you would appreciate that
. Also I think topical to the OP's interest and location.
. Also I think topical to the OP's interest and location.
Last edited by Concentric; 17th Nov 2018 at 16:27. Reason: Wee Doric smiley thing added PMSL.
In other words, the approach and departure should be parallel to the long bits of the H.
Shore side I wouldn't bet on it so much as some of the markings could have been installed by the "who knew" brigade as posted here.
Making sure that there are no bits sticking up between you and the pad has served well so far!
I would be careful with slavishly following that one as there are plenty of old decks around that are not marked correctly!
Shore side I wouldn't bet on it so much as some of the markings could have been installed by the "who knew" brigade as posted here.
Making sure that there are no bits sticking up between you and the pad has served well so far!
I would be careful with slavishly following that one as there are plenty of old decks around that are not marked correctly!
or was it just put down as ‘one of those things’ and the next guy or company which ‘wins’ the contract can sort it out?
Was only on the North Sea for 3-years and very surprised at the non-compliances that had been allowed to persist in a sector/industry which likes to think it sets the standards.
2-years spent off West Africa were ‘safer’ as you didn’t trust anyone to carry out their role properly so doubted everything from ATC to fuel checks and everything in between.
I’m assuming that all decks used by G-reg machines are marked correctly as we have a Helideck Certification Agency.
have to agree with you though - always check, never assume!
I’m assuming that all decks used by G-reg machines are marked correctly as we have a Helideck Certification Agency
Re HCA
I know, you just couldn’t make this stuff up.
when ‘new’ rigs were being commissioned and used in UZk waters and yet still had dated helitech design and lighting - and were still permitted to be used for CAT???
Lets be honest here folks - it took repeated accidents and public pressure to embarrass the CAA and other authorities into action. The stories of the CAA asking the operators which stone they were allowed to ‘look under’ are legendary and will cost someone a lot of money one day.
just as in the Financial Sector, the Light Touch tactics used by authorities had avoidable consequences.
I know, you just couldn’t make this stuff up.
when ‘new’ rigs were being commissioned and used in UZk waters and yet still had dated helitech design and lighting - and were still permitted to be used for CAT???
Lets be honest here folks - it took repeated accidents and public pressure to embarrass the CAA and other authorities into action. The stories of the CAA asking the operators which stone they were allowed to ‘look under’ are legendary and will cost someone a lot of money one day.
just as in the Financial Sector, the Light Touch tactics used by authorities had avoidable consequences.
If there was a bull’s eye target painted there - instead of the H (quite a good idea now I come to think of it) there would then, inevitably, be opinions on colour, size, positioning, and no doubt (someone would find a way) orientation. My first line trainer told me the H stood for “Hope” …. but I think he was joking.
Some people cannot read. I was in an area where we would winch personnel onto tankers. The winching area was marked with a big 'W'. One steely eyed pilot with another operator saw that the area around it was clear so he landed on to save time, all six tonnes of it.
The deck wasn't stressed for that so the ship had to go into the dockyard for a structural check.
Our company were flying that contract a few weeks later.
The deck wasn't stressed for that so the ship had to go into the dockyard for a structural check.
Our company were flying that contract a few weeks later.
Last edited by Fareastdriver; 19th Nov 2018 at 15:39.
