What is the circle on a helideck for?
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Originally Posted by Teefor Gage
Never heard such a lot of b*lls in my life. OK, so I have heard worse, but not on a "Professional Pilots" site!!
With a reply that that, I do not understand why The British won the war.
But I do understand why the Vikings conquered England in a few hours.
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Come on you guys, try to keep somewhere close to the original thread and don't take comments as personal insults. My comments are mere expressions of my own thoughts, be they good or bad, with the intent of encouraging further discussion on the subject.
I have many years of offshore experience under my belt, both on wheeled and skid fitted helicopters and know only too well how each on reacts on different surfaces, with or without nets, moving or stable.
OK, so a net might help to keep a little foam on the helideck but it is certainly not its primary purpose and I find it hard to believe it would make a substantial difference in the event of a real fuel fire. Maybe one of you less sensitive chaps out there can point me to the source of info on this??
As for lots of helidecks not having the correct tension due to the use of different methods of attachment and tightening, this doesn't surprise me but does demonstrate the ability of both helideck managers and pilots to accept "second best"!! If a net is fitted it should be secured and tensioned properly at all times.
OK, so who have I upset this time?
PS: Don't mention the war!!
I have many years of offshore experience under my belt, both on wheeled and skid fitted helicopters and know only too well how each on reacts on different surfaces, with or without nets, moving or stable.
OK, so a net might help to keep a little foam on the helideck but it is certainly not its primary purpose and I find it hard to believe it would make a substantial difference in the event of a real fuel fire. Maybe one of you less sensitive chaps out there can point me to the source of info on this??
As for lots of helidecks not having the correct tension due to the use of different methods of attachment and tightening, this doesn't surprise me but does demonstrate the ability of both helideck managers and pilots to accept "second best"!! If a net is fitted it should be secured and tensioned properly at all times.
OK, so who have I upset this time?
PS: Don't mention the war!!
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Nets
Originally Posted by 13snoopy
I HAVE A QUESTION!:
What is the netting I see in a lot of photos that is stretched across the decking area where a heli lands for? It would seem like this sort of thing would be dangerous to land on re the chances of a skid getting hung underneath, etc.
Thank you for any reply.
What is the netting I see in a lot of photos that is stretched across the decking area where a heli lands for? It would seem like this sort of thing would be dangerous to land on re the chances of a skid getting hung underneath, etc.
Thank you for any reply.
In the world of military air capable ships (helicopters, not jets) the nets are to make sure that if people get blown over by the downwash they don't go in the drink.
With regard to the original question, the circle on warship decks is designed such that if you put your main wheels anywhere in the circle (assuming, of course that the tail is pointing aft) the main rotor blades won't go 'boink' against anything.
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G'day LNT,
Much as I enjoyed my tuna time, this has to be classed as an improvement, if only for the standard of the tucker. I also appreciate the 2nd engine ocassionally, although I do miss the old "sun's gone, time for a quiet ale (or soju)" times. This flying in the dark caper has hairs on it I reckon.
OK, back to topic. On geared bulk carriers (landing between the crane and the bridge front), if you pick the middle of the circle, you avoid very expensive type noises.
That is of course if the circle is the correct diameter, but that's another story entirely.
Cheers,
MPT
Much as I enjoyed my tuna time, this has to be classed as an improvement, if only for the standard of the tucker. I also appreciate the 2nd engine ocassionally, although I do miss the old "sun's gone, time for a quiet ale (or soju)" times. This flying in the dark caper has hairs on it I reckon.
OK, back to topic. On geared bulk carriers (landing between the crane and the bridge front), if you pick the middle of the circle, you avoid very expensive type noises.
That is of course if the circle is the correct diameter, but that's another story entirely. Cheers,
MPT
Gatvol
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Circle is the same as a Bullseye in Darts. You hit it, you win.....
If there is a number inside....its the amount of times the usual piolt takes to hit it correctly.
As been said its the aiming point for a safe landing for certain size Helicopters, make sure you know that before you take your MI-26 in a small one.
Number inside usually refers to class or size that the pad will support
If there is a number inside....its the amount of times the usual piolt takes to hit it correctly.
As been said its the aiming point for a safe landing for certain size Helicopters, make sure you know that before you take your MI-26 in a small one.
Number inside usually refers to class or size that the pad will support
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I think it is a bit of an old wives tale that the aiming circle is just that and you can judge your approach angle from the ovoid or otherwise shape of the circle. At night you can't see it, you look for the blackest hole and the odds are you will find the deck there, when you get there you find the circle is partially obscured with bird poop, by this time you have almost hit the thing so as an approach aid it is next to useless.
In practicle terms the circle is sized to 50% of the deck size i.e. 16 metre deck, D value of 16. The inner measurement of the circle is 8m. If you land with the nose of the helicopter on the circle (bum line for the S61 drivers, because that's where you put it) you can be sure that the stickyout bits at the back and front will always be clear of obstruction. This only works if you land your helicopter that has a D value of 16 or less, stick your Puma/Tiger or S61 there you have more than one problem. This should't happen because we all know our particular helicopters' D value and the meaning of all the other deck markings.
Helidecks that meet all the requirements are very few indeed and teefor gage is right when he says pilots are to blame. Too many go for the easy life and don't make reports, it is so easy to put restrictions on helidecks that are poor so that sooner or later they bite and repairs/cleaning is carried out.
I can see I'm boring you so I will wind my neck in, until the next time that is.
In practicle terms the circle is sized to 50% of the deck size i.e. 16 metre deck, D value of 16. The inner measurement of the circle is 8m. If you land with the nose of the helicopter on the circle (bum line for the S61 drivers, because that's where you put it) you can be sure that the stickyout bits at the back and front will always be clear of obstruction. This only works if you land your helicopter that has a D value of 16 or less, stick your Puma/Tiger or S61 there you have more than one problem. This should't happen because we all know our particular helicopters' D value and the meaning of all the other deck markings.
Helidecks that meet all the requirements are very few indeed and teefor gage is right when he says pilots are to blame. Too many go for the easy life and don't make reports, it is so easy to put restrictions on helidecks that are poor so that sooner or later they bite and repairs/cleaning is carried out.
I can see I'm boring you so I will wind my neck in, until the next time that is.
An interesting thread and a wide spread of ideas: all credit to ‘roundwego’ for the quote from CAP 437; and to ‘Silberfuchs’ for a pointer to the Canadian Regulations and CAP 437 (not yet the JAA Spec.). Interestingly in the Canadian regulations in Fig. 4 Helicopter Decks, the ‘aiming circle’ appeared to be about 0.25D which - if in accordance with the requirement for it to be 6m - would have made the size of the deck about 24m. This appears to be in conflict with the un-amended ICAO Standard which calls for the inner dimensions of the circle to be “half the D value of the helideck or 6m whichever is the greater” (the amended version will specify only an ‘Aiming/Positioning Marking” with the inner dimensions half the D value of the helideck).
Leaving aside the discussion on the net - which was not the subject of the thread but which has been well covered; and an interesting side discussion about the ovality of the deck lights in assessing the glide slope at night (not really sure what the relevance of that was to pinnacle landings); on the original question there appear to be three different schools of thought:
1. Those who thought that the aiming circle was an S61 anachronism, the pilots landing in the centre of the deck; this could work and is an interesting method but does rely upon the (exceptional) judgement of the pilot knowing (a) where the centre of the deck is and (b) more importantly, where the centre of the helicopter is - and matching one to the other.
2. One view that “if you put your main wheels anywhere in the circle…the main rotor blades won’t go ‘boink’ against anything”; once again it would work but it does rather rely upon the main wheels being in the centre of the helicopter (see the discussion later) and in any case, unless it is a small circle in the centre of the deck, there is too much leeway (the size of the deck would then have to reflect that). The circle could be tailored to the particular helicopter and be made smaller to reduce the leeway but why have a circle in which to ‘put the wheels’ when what is required is a ‘visual cue’ for the pilot that can be used without having to see where the wheels are. If, as implied, the tail always has to point aft then no more than a shoulder line would be necessary. (Note that skidded helicopters were not considered.)
3. Those who considered that the circle is a ‘bum line’ on which the pilot positions himself/herself. ‘Check’ - in a well argued post - almost agreed with this but stated that it was the ‘nose’ of the helicopter that had to be on the aiming circle (which with an S76, EC155 or AW139 on a 1D deck, would put the tail two metres into the obstacle environment).
As ‘check’ says, the aiming circle should have an inner circle 0.5 times the declared size of the deck (declared in the markings at the edge of the FATO - not in the aiming circle) with a 1m yellow boundary; it is situated in the middle of the deck unless using the permitted offset of 0.1D (ICAO and CAP 437).
Positioning on the helideck by using the wheels/skids is not accurate enough; the S76, EC155, AW139 have all of their wheels ahead of the centre line; the AS332, EC225 and S92 have their main wheels aft of the centre line and their nose wheels forward; the S61 and S70 have the main wheels forward of the centre line and the tail wheel aft (in the S70 by a considerable distance). The length of undercarriages ranges extensively - suffice to say that if you want to have an area in which the wheels/skids are always contained it will require a circle of 0.83D (centred on FATO).
In spite of variations in size of helicopters and configuration of wheels and skids; for all single rotor helicopters recently examined it was observed that, for a 1D deck, when the pilots seat is positioned on a circle of 0.5D, all of the parts of most helicopters will be within the boundaries of the deck and where there are exceptions, the extent of the overlap of the boundary is measured in centimetres. (Remember that on a 1D deck the main rotor is already at the front edge and the tail rotor (fenestron) at the back edge).
Regardless of the type of helicopter; when landing on a deck (which is of a size of 1D or greater), positioning with the pilot’s seat on the 0.5D (of the size of the helideck) aiming circle will always provide the pilot with the safest option. When using any other method, or when using a circle of any other size, there is a possibility of an unsafe outcome.
Jim
Leaving aside the discussion on the net - which was not the subject of the thread but which has been well covered; and an interesting side discussion about the ovality of the deck lights in assessing the glide slope at night (not really sure what the relevance of that was to pinnacle landings); on the original question there appear to be three different schools of thought:
1. Those who thought that the aiming circle was an S61 anachronism, the pilots landing in the centre of the deck; this could work and is an interesting method but does rely upon the (exceptional) judgement of the pilot knowing (a) where the centre of the deck is and (b) more importantly, where the centre of the helicopter is - and matching one to the other.
2. One view that “if you put your main wheels anywhere in the circle…the main rotor blades won’t go ‘boink’ against anything”; once again it would work but it does rather rely upon the main wheels being in the centre of the helicopter (see the discussion later) and in any case, unless it is a small circle in the centre of the deck, there is too much leeway (the size of the deck would then have to reflect that). The circle could be tailored to the particular helicopter and be made smaller to reduce the leeway but why have a circle in which to ‘put the wheels’ when what is required is a ‘visual cue’ for the pilot that can be used without having to see where the wheels are. If, as implied, the tail always has to point aft then no more than a shoulder line would be necessary. (Note that skidded helicopters were not considered.)
3. Those who considered that the circle is a ‘bum line’ on which the pilot positions himself/herself. ‘Check’ - in a well argued post - almost agreed with this but stated that it was the ‘nose’ of the helicopter that had to be on the aiming circle (which with an S76, EC155 or AW139 on a 1D deck, would put the tail two metres into the obstacle environment).
As ‘check’ says, the aiming circle should have an inner circle 0.5 times the declared size of the deck (declared in the markings at the edge of the FATO - not in the aiming circle) with a 1m yellow boundary; it is situated in the middle of the deck unless using the permitted offset of 0.1D (ICAO and CAP 437).
Positioning on the helideck by using the wheels/skids is not accurate enough; the S76, EC155, AW139 have all of their wheels ahead of the centre line; the AS332, EC225 and S92 have their main wheels aft of the centre line and their nose wheels forward; the S61 and S70 have the main wheels forward of the centre line and the tail wheel aft (in the S70 by a considerable distance). The length of undercarriages ranges extensively - suffice to say that if you want to have an area in which the wheels/skids are always contained it will require a circle of 0.83D (centred on FATO).
In spite of variations in size of helicopters and configuration of wheels and skids; for all single rotor helicopters recently examined it was observed that, for a 1D deck, when the pilots seat is positioned on a circle of 0.5D, all of the parts of most helicopters will be within the boundaries of the deck and where there are exceptions, the extent of the overlap of the boundary is measured in centimetres. (Remember that on a 1D deck the main rotor is already at the front edge and the tail rotor (fenestron) at the back edge).
Regardless of the type of helicopter; when landing on a deck (which is of a size of 1D or greater), positioning with the pilot’s seat on the 0.5D (of the size of the helideck) aiming circle will always provide the pilot with the safest option. When using any other method, or when using a circle of any other size, there is a possibility of an unsafe outcome.
Jim
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Yeh, we all know that the circle is something to aim for, but, especially on geared ships( ships with cranes and other structures), it all comes down to how smart the cheap arse, slave laboured, non english speaking deck worker, was in reading the measuring tape, with the brush in his hand.
JimL,
Can you put that into plain old tea room English?
It gets back to my questions....what is a standard circle? What is a standard helicopter?
If one flys for Mobil in Nigeria there is no such thing as a standard circle. Those that have flown there can easily describe the railroad track decks (the old wooden decks platforms that had all of the wood removed from the two I-beam supports that required one to land parallel to the I-beams.
Or....perhaps the survey boats that have the fold down helidecks that are marked for small aircraft and not the mediums being used.
The comment about landing on a pinnacle comparison defeats most RN pilots I know. They prefer to arrive at a hover and transition across to the deck as if there is a marshaller waving wands at them clearing them to the 3 Spot.
The elevated helideck is simply a pinnacle landing without the mountains. The deck markings are useful if they have any pertinance to the aircraft you happen to be flying at the time. Angle of descent and rate of closure are discernable by the rig/platform apparant movement and deck alone with the markings being just something else to use to ad detail to the deck surface. Nets work a treat for that purpose as well.
Does this not get back to basics....standard entry height above the water, standard speed, find the angle....maintain the angle and rate of closure till you pick up all those cues as you approach the deck surface. (Remember the old Chinagraph (grease pencil) mark on the windscreen? I will bet you that a survey of decks will show a decided favor of landing towards the uncluttered edge vice bum on circle in the exact center of the deck.
One simply has to know where to place the wheels/skids on each deck to ensure avoiding the 'boinking noises"....and that depends more on the geometry of the landing gear compared to the bits that are flopping about looking for something to beat themselves to death upon than the "D's and .5D's" crap.
Can you put that into plain old tea room English?
It gets back to my questions....what is a standard circle? What is a standard helicopter?
If one flys for Mobil in Nigeria there is no such thing as a standard circle. Those that have flown there can easily describe the railroad track decks (the old wooden decks platforms that had all of the wood removed from the two I-beam supports that required one to land parallel to the I-beams.
Or....perhaps the survey boats that have the fold down helidecks that are marked for small aircraft and not the mediums being used.
The comment about landing on a pinnacle comparison defeats most RN pilots I know. They prefer to arrive at a hover and transition across to the deck as if there is a marshaller waving wands at them clearing them to the 3 Spot.
The elevated helideck is simply a pinnacle landing without the mountains. The deck markings are useful if they have any pertinance to the aircraft you happen to be flying at the time. Angle of descent and rate of closure are discernable by the rig/platform apparant movement and deck alone with the markings being just something else to use to ad detail to the deck surface. Nets work a treat for that purpose as well.
Does this not get back to basics....standard entry height above the water, standard speed, find the angle....maintain the angle and rate of closure till you pick up all those cues as you approach the deck surface. (Remember the old Chinagraph (grease pencil) mark on the windscreen? I will bet you that a survey of decks will show a decided favor of landing towards the uncluttered edge vice bum on circle in the exact center of the deck.
One simply has to know where to place the wheels/skids on each deck to ensure avoiding the 'boinking noises"....and that depends more on the geometry of the landing gear compared to the bits that are flopping about looking for something to beat themselves to death upon than the "D's and .5D's" crap.
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G'day All,
LNT,
, I don't actually recall "aiming circles" on the boats, all I know is that I had a leeway of around 3 inches in any direction or the belly hook tie down wasn't in the right position. It certainly taught me to look AT what I'm about to put my skids on rather than out the front!!
SASL, We've seen the "hover over the water" problem with ex navy guys coming into the MPT stuff. It's very scary when they try and hover OGE off the side of a perfectly good IGE deck (especially at night). Quite often, on the ungeared vessels, we completely ignore the circle (non slip paint is the exception rather than the rule on >90% of the ships we see) and land on a clear spot on the marked hatch cover in order to hang the T/R over the edge and out of the way of suicidal crew members
Cheers,
MPT
LNT,
, I don't actually recall "aiming circles" on the boats, all I know is that I had a leeway of around 3 inches in any direction or the belly hook tie down wasn't in the right position. It certainly taught me to look AT what I'm about to put my skids on rather than out the front!!SASL, We've seen the "hover over the water" problem with ex navy guys coming into the MPT stuff. It's very scary when they try and hover OGE off the side of a perfectly good IGE deck (especially at night). Quite often, on the ungeared vessels, we completely ignore the circle (non slip paint is the exception rather than the rule on >90% of the ships we see) and land on a clear spot on the marked hatch cover in order to hang the T/R over the edge and out of the way of suicidal crew members
Cheers,
MPT
SASless,
Let me attempt to answer two of the questions you have asked - or more correctly put my previous answer into context.
A standard ‘touchdown marking’ (soon to be called the ‘touchdown/positioning marking’) is a circle with the inner diameter of half the ‘D’ value of the helideck; the line width should be 1m. That these circles are not 0.5D in Nigeria does not alter the fact that it is the de jure Standard, only that the Standard is not being applied - the same is true for survey boats.
I totally agree with ‘check’ that a non-standard marking should be reported (confidentially if necessary). Once it has been reported that the ‘touchdown marking’ is incorrectly marked/positioned, any accident/incident that results from the incorrect marking will then be the joint responsibility of the ‘duty holder’ and the ‘operator’; an extremely powerful way of achieving rectification.
The second question - what is a ‘standard helicopter’ was addressed in my first post; to expand further, the 0.5D appears to be a ‘magic circle’ - go to the Flight Manual of your offshore helicopter and measure from the end of the tail rotor to the pilot’s seat, it usually comes out extremely close to 0.75D. There is no such thing as a standard helicopter but, as a generic marking to assist the pilot with the positioning of any helicopter on a helideck, it is as good as it gets (without individual tailoring). The geometry of the undercarriage appears to have no relevance to this equation.
The geometry of the undercarriage does have relevance to the size of the required TLOF - required in the sense that it will work for any helicopter within the D limits of the helideck - which has to be as large as 0.83D.
I would not disagree with your contention “one simply has to know where to place the wheels/skids on each deck to ensure avoiding the ‘boinking noises’” - but it results in an individual exercise for each deck and for each specific helicopter; for that reason I fail to see why you regard the use of ‘D’ and the ‘0.5D’ touchdown marking as crap.
As an initiator of many a call for safer practices, surely you see the logic of the use of an existing, and safe, Standard.
Jim
Let me attempt to answer two of the questions you have asked - or more correctly put my previous answer into context.
A standard ‘touchdown marking’ (soon to be called the ‘touchdown/positioning marking’) is a circle with the inner diameter of half the ‘D’ value of the helideck; the line width should be 1m. That these circles are not 0.5D in Nigeria does not alter the fact that it is the de jure Standard, only that the Standard is not being applied - the same is true for survey boats.
I totally agree with ‘check’ that a non-standard marking should be reported (confidentially if necessary). Once it has been reported that the ‘touchdown marking’ is incorrectly marked/positioned, any accident/incident that results from the incorrect marking will then be the joint responsibility of the ‘duty holder’ and the ‘operator’; an extremely powerful way of achieving rectification.
The second question - what is a ‘standard helicopter’ was addressed in my first post; to expand further, the 0.5D appears to be a ‘magic circle’ - go to the Flight Manual of your offshore helicopter and measure from the end of the tail rotor to the pilot’s seat, it usually comes out extremely close to 0.75D. There is no such thing as a standard helicopter but, as a generic marking to assist the pilot with the positioning of any helicopter on a helideck, it is as good as it gets (without individual tailoring). The geometry of the undercarriage appears to have no relevance to this equation.
The geometry of the undercarriage does have relevance to the size of the required TLOF - required in the sense that it will work for any helicopter within the D limits of the helideck - which has to be as large as 0.83D.
I would not disagree with your contention “one simply has to know where to place the wheels/skids on each deck to ensure avoiding the ‘boinking noises’” - but it results in an individual exercise for each deck and for each specific helicopter; for that reason I fail to see why you regard the use of ‘D’ and the ‘0.5D’ touchdown marking as crap.
As an initiator of many a call for safer practices, surely you see the logic of the use of an existing, and safe, Standard.
Jim
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saw a program on discovery wings last night showing a wasp turning into wind on a ship Lz using the wheels and keeping them in the circle
ITS A MINI ROUNDABOUT LOL
ITS A MINI ROUNDABOUT LOL
Originally Posted by md 600 driver
saw a program on discovery wings last night showing a wasp turning into wind on a ship Lz using the wheels and keeping them in the circle
ITS A MINI ROUNDABOUT LOL
ITS A MINI ROUNDABOUT LOL
Oh, wait, sorry...I didn't mention that we had a circle on the deck...I think all three of their wheels were in it most of the time...there...managed to stay with the thread after all.
Jim,
All that being said and nicely translated....I found the practice, of an operator we both worked for in the past, of doing an inspection of all decks and markings upon start of an operation or when new decks were put into operation worked to prevent any such problems.
As others have mentioned, monitoring the condition of the decks and reporting as a standard procedure by the Safety Officer, Training Captain, Captains, and Chief Pilot works towards discovering problems. A good Safety Program will also have a system that follows up on reported problems and ensures hazardous issues are resolved, shutting down decks if necessary until corrective action is taken.
All that being said and nicely translated....I found the practice, of an operator we both worked for in the past, of doing an inspection of all decks and markings upon start of an operation or when new decks were put into operation worked to prevent any such problems.
As others have mentioned, monitoring the condition of the decks and reporting as a standard procedure by the Safety Officer, Training Captain, Captains, and Chief Pilot works towards discovering problems. A good Safety Program will also have a system that follows up on reported problems and ensures hazardous issues are resolved, shutting down decks if necessary until corrective action is taken.
After considering the responses to this thread, it was clear that, although most were aware of the presence of the circle on the helideck (soon to be also used on heliports), these markings were not in use throughout the world - even though they are essential elements of safety for offshore operations.
The continuing work on Annex 14 Part II (heliports) has resulted in amended Standards and Recommended Practices for helideck/heliports, one of which is the acceptance of helidecks of less than 1D for helicopters below 3,175kg (7,000lbs). There has also been acceptance that even with 1D (or larger) decks, accurate positioning is critical to safe operations (an incident in Norway where a pilot performed a spot turn, without maintaining positioning on the Touchdown and Positioning Markings (TD/PM) - i.e. the bum line, indicated that there was room for further reinforcement of the reasons for markings and accurate positioning.)
In view of that we took a commitment to produce a paper to explain the principles behind the markings, and explain why their use is important. That paper has now been produced and the Helideck Certification Agency (HCA) has kindly agreed to host the paper on their site. It can be found at:
http://www.helidecks.org/download%20...r%20V1%209.pdf
We welcome any comments on this paper and will amend it in accordance with those comments.
NB the revised Standard for helidecks of less than 1D can be found at Appendix C to this paper.
Jim
The continuing work on Annex 14 Part II (heliports) has resulted in amended Standards and Recommended Practices for helideck/heliports, one of which is the acceptance of helidecks of less than 1D for helicopters below 3,175kg (7,000lbs). There has also been acceptance that even with 1D (or larger) decks, accurate positioning is critical to safe operations (an incident in Norway where a pilot performed a spot turn, without maintaining positioning on the Touchdown and Positioning Markings (TD/PM) - i.e. the bum line, indicated that there was room for further reinforcement of the reasons for markings and accurate positioning.)
In view of that we took a commitment to produce a paper to explain the principles behind the markings, and explain why their use is important. That paper has now been produced and the Helideck Certification Agency (HCA) has kindly agreed to host the paper on their site. It can be found at:
http://www.helidecks.org/download%20...r%20V1%209.pdf
We welcome any comments on this paper and will amend it in accordance with those comments.
NB the revised Standard for helidecks of less than 1D can be found at Appendix C to this paper.
Jim
Last edited by JimL; 16th May 2011 at 13:33. Reason: Changed reference for the 1.9 version of the paper
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& I always thought on warships the circle was there as all You Jolly Jack Tars like a chopper in Your ring 
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