Offshore Helideck Ops
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Approach Angle to Helideck
There has been much debate on the "correct " angle of approach on to an offshore platform. What would be an ideal angle of approach in a nil wind situation that will allow a safe single engine landing to the deck?
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You may get a lot of answers to this, but my method in an S76 is to put the pitot tube on the far edge of the helideck and keep it there. In a 412, I do close to the same, but I generally try to just be able to see the far side over the glareshield. I tend to sit higher than many other pilots, though, so this may not work for everyone. I suspect, from the seat adjustments I have to make when I follow other pilots into the aircraft, that many of them couldn't see the pitot tube at all.
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This has been done a few times, but I can't find the threads.
GLSNightPilot was correct, there are a heap of attitudes on this subject, all with some element of truth to it.
I must correct/clarify one part of your post.....My philosophy is never to land on an offshore platform OEI, and to do everything possible to avoid that occurring.
And why??
1.. Apart from a small handful of heavy twins, SA332L1 & 2, B214ST, not sure about the S61, no other twin has the certification to hold OEI onto Offshore Platforms, in other words other helicopters which include the two mentioned by GLS can not undertake OEI platform landings and survive intact every time. There is normally heaps of discussion on my last statement, including SIM justification that it’s possible. From my experience an Instructor can always have you crashing a high % of the time when trying to undertake this in practice....don't give yourself false expectations.
2.. An Oil Platform is a hard dangerous place to go at the best of times, yet alone OEI. Avoid them like the plague in an OEI in a medium twin.
3.. The owner of the Offshore Platform would normally not appreciate you landing OEI on his/her platform when you could quite easily take the passengers home with you. A platform worth a few hundred million dollars and 100+ POB verses an old medium helicopter worth one or two million and a handful of POB says it all.
[Now if your working where onshore alt fuel is not carried, then perhaps you should take swimming lessons]
Gnow....To your question.....
At all stages of your approach, have the mindset that you are not going to land on that platform until that point in space when it becomes impossible to avoid the platform....and that point is called "Committed".
Any OEI prior to "Committed" then pull 2.5 mins OEI power and VTOSS and get out of Dodge.
After "Committed" its always possible to arrive onto the platform OEI, because you have planned the approach.
The aiming point should be the side of the helideck closest to your side of the approach, which means you can leave the "Committed" call to a later point in space than if you aimed at the centre of the circle.
Whilst this approach resembles CAT A profiles...it is not CAT A [but that is another topic]....
Whilst GLS utilises a fixed aiming point of his aircraft, this style of approach is not sound in all conditions.
In Nil Wind and a hot humid day, you will have your work really cut out for you in an OEI configuration....if you are low and slow, then you will fall short for sure and not have the power to continue to the deck edge, your ITT, N1 will be accelerating up to their limits with the Nr decreasing, and you pulling more power to make the edge......don't go there, plan your "Committed" position with AEO and fly to it.
If you are on a High Approach, then you now have the same problem caused by different elements, but the result will be the same on a hot windless day with an OEI , large power demands to arrest a descending helicopter causing ITT and N1 increases and a reducing Nr. Bet you can't do that in practice without wrecking something....at least most of the time.
So don't get yourself in those positions in the first place......I suggest getting into the final approach at 80 knts and 500 feet Rad Alt and then aiming to be at your "Committed" position AEO at around 15 knts and 15 - 20 feet above but to the edge of your platform.
Then you should survive and your aircraft not damaged. [Fingers crossed]
I must correct/clarify one part of your post.....My philosophy is never to land on an offshore platform OEI, and to do everything possible to avoid that occurring.
And why??
1.. Apart from a small handful of heavy twins, SA332L1 & 2, B214ST, not sure about the S61, no other twin has the certification to hold OEI onto Offshore Platforms, in other words other helicopters which include the two mentioned by GLS can not undertake OEI platform landings and survive intact every time. There is normally heaps of discussion on my last statement, including SIM justification that it’s possible. From my experience an Instructor can always have you crashing a high % of the time when trying to undertake this in practice....don't give yourself false expectations.
2.. An Oil Platform is a hard dangerous place to go at the best of times, yet alone OEI. Avoid them like the plague in an OEI in a medium twin.
3.. The owner of the Offshore Platform would normally not appreciate you landing OEI on his/her platform when you could quite easily take the passengers home with you. A platform worth a few hundred million dollars and 100+ POB verses an old medium helicopter worth one or two million and a handful of POB says it all.
[Now if your working where onshore alt fuel is not carried, then perhaps you should take swimming lessons]
Gnow....To your question.....
At all stages of your approach, have the mindset that you are not going to land on that platform until that point in space when it becomes impossible to avoid the platform....and that point is called "Committed".
Any OEI prior to "Committed" then pull 2.5 mins OEI power and VTOSS and get out of Dodge.
After "Committed" its always possible to arrive onto the platform OEI, because you have planned the approach.
The aiming point should be the side of the helideck closest to your side of the approach, which means you can leave the "Committed" call to a later point in space than if you aimed at the centre of the circle.
Whilst this approach resembles CAT A profiles...it is not CAT A [but that is another topic]....
Whilst GLS utilises a fixed aiming point of his aircraft, this style of approach is not sound in all conditions.
In Nil Wind and a hot humid day, you will have your work really cut out for you in an OEI configuration....if you are low and slow, then you will fall short for sure and not have the power to continue to the deck edge, your ITT, N1 will be accelerating up to their limits with the Nr decreasing, and you pulling more power to make the edge......don't go there, plan your "Committed" position with AEO and fly to it.
If you are on a High Approach, then you now have the same problem caused by different elements, but the result will be the same on a hot windless day with an OEI , large power demands to arrest a descending helicopter causing ITT and N1 increases and a reducing Nr. Bet you can't do that in practice without wrecking something....at least most of the time.
So don't get yourself in those positions in the first place......I suggest getting into the final approach at 80 knts and 500 feet Rad Alt and then aiming to be at your "Committed" position AEO at around 15 knts and 15 - 20 feet above but to the edge of your platform.
Then you should survive and your aircraft not damaged. [Fingers crossed]
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The luxury of flying offshore at night in rainy conditions.
It is great to be a helicopter pilot, especially when we dont fly in a controlled-runway environment with approach aids and lighting such as an ILS, VASIs, etc.
The way I view approach angles offshore will be based on a combination of variables, such as the type of helicopter you fly, layout of the offshore installation and the prevailing weather conditions.
I have seen the different approach angles in flying a Super Puma and S76, especially when looking at the performance during OEI operations (simulated of course). So what I am saying is that with a Super Puma's performance one can commit at a much later stage of the approach and be assured a controlled landing at the bottom (Good OEI performance at most weights).
In the case of the S76, the opposite holds the truth. I prefer a higher approach angle to give me the extra margin for safety and to increase my flyaway chances and once committed, it will at least get me on the deck without undershooting and clipping the edge of the deck (Poor OEI performance at all weights).
Since I use to be a rugby player, this picture works quite well for me. Regardless of your height and distance from the platform, once the helideck lighting opens up in the shape of a rugby ball or almond, that is the approach angle I fly down towards the deck. It sounds basic, but it works for me.
Best wishes and safe flying for 2004.
Cheers,
Chopper Jog
It is great to be a helicopter pilot, especially when we dont fly in a controlled-runway environment with approach aids and lighting such as an ILS, VASIs, etc.
The way I view approach angles offshore will be based on a combination of variables, such as the type of helicopter you fly, layout of the offshore installation and the prevailing weather conditions.
I have seen the different approach angles in flying a Super Puma and S76, especially when looking at the performance during OEI operations (simulated of course). So what I am saying is that with a Super Puma's performance one can commit at a much later stage of the approach and be assured a controlled landing at the bottom (Good OEI performance at most weights).
In the case of the S76, the opposite holds the truth. I prefer a higher approach angle to give me the extra margin for safety and to increase my flyaway chances and once committed, it will at least get me on the deck without undershooting and clipping the edge of the deck (Poor OEI performance at all weights).
Since I use to be a rugby player, this picture works quite well for me. Regardless of your height and distance from the platform, once the helideck lighting opens up in the shape of a rugby ball or almond, that is the approach angle I fly down towards the deck. It sounds basic, but it works for me.
Best wishes and safe flying for 2004.
Cheers,
Chopper Jog
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A friend of mine went for his simulator check on the S61N and was told that normally the approach angle is about 30 degrees. So for a 22m deck when we cross the deck edge we should be theoritically 40 ft above the deck edge (using sine,cosine formulas). I tried this but it looks rather low.However, I find a lot of pilots in trying to do steep approach ending up in a high hover over the deck.
I'm with GLS on this one.
Steep is good, shallow is bad.
You really need to have your rate of decent and airspeed under control for the nil wind, hot approach. Otherwise it is not the engine failure but the crane at the end of the deck that smokes you.
Post your committed point you want to guarantee to land on the deck and not the kitchen.
I also sit high and use the pitot's as a lead on the 76. Its worked perfectly for the last 4000 odd offshore and onshore landings.
Plan to arrive alive
Steep is good, shallow is bad.
You really need to have your rate of decent and airspeed under control for the nil wind, hot approach. Otherwise it is not the engine failure but the crane at the end of the deck that smokes you.
Post your committed point you want to guarantee to land on the deck and not the kitchen.
I also sit high and use the pitot's as a lead on the 76. Its worked perfectly for the last 4000 odd offshore and onshore landings.
Plan to arrive alive
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Approach Angle:
CHC Intl uses 500ft/0.75nm
Landing on a deck of 100ft above sea level, this will give you a 5-5.5 deg approach angle. I think the 30 deg angle is close to an autorotation if you compare it to a normal ILS of 3 degrees. I also believe that the Norwegians have a Copter ILS that is calibrated at a 7-degree approach angle.
At least the 30-degree approach angle will give you sufficient height if you decide to use that. Safe flying!!
CJ
I have used the TAN Formula whereby the distance over the ground is 0.75nm = 4500ft (a) and the height above the deck is 400ft (0), this give the approach angle (Q) of about 5 degrees
Correct me if I am wrong.
CHC Intl uses 500ft/0.75nm
Landing on a deck of 100ft above sea level, this will give you a 5-5.5 deg approach angle. I think the 30 deg angle is close to an autorotation if you compare it to a normal ILS of 3 degrees. I also believe that the Norwegians have a Copter ILS that is calibrated at a 7-degree approach angle.
At least the 30-degree approach angle will give you sufficient height if you decide to use that. Safe flying!!
CJ
I have used the TAN Formula whereby the distance over the ground is 0.75nm = 4500ft (a) and the height above the deck is 400ft (0), this give the approach angle (Q) of about 5 degrees
Correct me if I am wrong.
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Irritating Amateur Question
In an earlier thread about helideck landings, it appeared that there is a 'reference position' in the S-76 (and for all I know other types) which guarantees the eye height of the pilot - one gets in and fiddles with seat adjustment until the standard sighting cues are met.
It sounds as though the pitot is invisible from the reference position.
Can anyone explain where I'm going wrong?
It sounds as though the pitot is invisible from the reference position.
Can anyone explain where I'm going wrong?
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Nervy, Rotorheads is aimed at pros (it's in the forum description). Therefore they don't have to speak English; they can talk shop.
I'm not a pro myself (in fact I'm barely even an amateur), but I read all the threads and try to work out as many things for myself as I can. It helps that I subscribe to JAR-OPS3 (the manual that covers AOC Helicopter operations); and you can bet the pros (certainly in Europe) have very easy access to that.
In this case, OEI is 'One Engine Inoperative'. By contrast, AEO is 'All Engines Operating'.
I'm not a pro myself (in fact I'm barely even an amateur), but I read all the threads and try to work out as many things for myself as I can. It helps that I subscribe to JAR-OPS3 (the manual that covers AOC Helicopter operations); and you can bet the pros (certainly in Europe) have very easy access to that.
In this case, OEI is 'One Engine Inoperative'. By contrast, AEO is 'All Engines Operating'.
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VTOSS
Mr. Shelfish is correct, and a full definition.
"Is that speed at your 2.5 minute OEI power setting that will ensure a ROC [Rate of Climb] of 100 feet per min" in ambient conditions.....look in you RFM. [Rotorcraft Flight Manual]...it should be stated.
"Is that speed at your 2.5 minute OEI power setting that will ensure a ROC [Rate of Climb] of 100 feet per min" in ambient conditions.....look in you RFM. [Rotorcraft Flight Manual]...it should be stated.
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Approach angle
I agree with all post concerning the steeper approach angle is desirable. In the the event of an engine failure after your "Committed" or "LDP" flying the B412 or 212 with PT6-3B twin pack I like to have my rotor disc cross the deck at 55% Xsms torque or less. This will leave in reserve up to 18% ENG TQ available for cushioning with your operating engine on a IAS day. But, with the 3B's your limiting factors will be ITT or N1. (Not sure if I care at that point) Just as long as my feet are dry.
This technique is difficult and uncomfortable on a no wind day so I tend to be a bit slower with no wind. Placing more trust in Pratt and Whitney.
As far as sight picture a high seat position makes it easier to fly the steeper angles by keeping the deck in view.
Somebody mentioned settling with power which should not a factor as long as your not in a downwind condition and leaving your vortices behind you. Remember, you need all three factors to settle with power. ROD 300 fpm or greater, 20% to 100% power applied and zero near zero airspeed. By the time you have near zero airspeed you'll be IGE.
This was an interesting post and and I appreciate the exchange of ideas and techniques. There is a lot of ambiguity and many ways to skin a cat!
Cheers.............
This technique is difficult and uncomfortable on a no wind day so I tend to be a bit slower with no wind. Placing more trust in Pratt and Whitney.
As far as sight picture a high seat position makes it easier to fly the steeper angles by keeping the deck in view.
Somebody mentioned settling with power which should not a factor as long as your not in a downwind condition and leaving your vortices behind you. Remember, you need all three factors to settle with power. ROD 300 fpm or greater, 20% to 100% power applied and zero near zero airspeed. By the time you have near zero airspeed you'll be IGE.
This was an interesting post and and I appreciate the exchange of ideas and techniques. There is a lot of ambiguity and many ways to skin a cat!
Cheers.............
so, how many have done it?
how many of all the posers (sorry, posters) on this thread have done it. OEI that is; I haven't.
And a happy new year to all of us and let's hope we do not have to do it.
Happy Landings OEI or AEO from the Northsea.
And a happy new year to all of us and let's hope we do not have to do it.
Happy Landings OEI or AEO from the Northsea.
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In a previous life, I was operating out of Juhu Airport, Mumbai, India with 6 x B412's on Offshore Operations.
I guess the feeling amongst the majority of the national flightcrew was that there was far to much emphasis placed on OEI and other emergency aspects of flying.
That belief soon changed, after an OEI developed when a Senior [Now retired ] Captain and a Senior F/O were approaching a Jackup Platform.
From the transcript of the CVR [including the engine noise from the cockpit microphone], its was obvious that their OEI approach commenced simultaneously with the First Officers [Flying Pilot] "Committed" call.
The end result was that the heavy B412, skidded about one [1] metre on the deck, and came to rest about half way between the deck edge and the circle, just where the Flying Pilot was aiming for.
The remaining engine suffered no transient excursions, which was verified by the electronic monitoring equipment installed.
"Thecopper"...that is one that I have witnessed close up, and there have been others in Australia over the years.
Happy New Year to you all.
I guess the feeling amongst the majority of the national flightcrew was that there was far to much emphasis placed on OEI and other emergency aspects of flying.
That belief soon changed, after an OEI developed when a Senior [Now retired ] Captain and a Senior F/O were approaching a Jackup Platform.
From the transcript of the CVR [including the engine noise from the cockpit microphone], its was obvious that their OEI approach commenced simultaneously with the First Officers [Flying Pilot] "Committed" call.
The end result was that the heavy B412, skidded about one [1] metre on the deck, and came to rest about half way between the deck edge and the circle, just where the Flying Pilot was aiming for.
The remaining engine suffered no transient excursions, which was verified by the electronic monitoring equipment installed.
"Thecopper"...that is one that I have witnessed close up, and there have been others in Australia over the years.
Happy New Year to you all.
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While I've done it countless times simulated (both in the aircraft and simulator) I've never had an actual engine failure. I keep expecting my first one on every flight, but it hasn't happened.
If I have any advantage, it's that I'm flying an S76A++ with plenty of power, and usually relatively lightly loaded, so I can often hover OEI. That partially makes up for doing it in the dark. My method works in training, but I've never had to try it for real.
If I have any advantage, it's that I'm flying an S76A++ with plenty of power, and usually relatively lightly loaded, so I can often hover OEI. That partially makes up for doing it in the dark. My method works in training, but I've never had to try it for real.
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There has been one OEI recovery to a platfrom following an engne fire indication in Bass Strait. Ross M completed a safe OEI landing onto a platform after shutting down one of the engines in a S-76C.
Cheers
Cheers
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Q: Use of compass DG mode - Offshore?
Need some good user input...
Looking for folks who operate off oil platforms or in the Canadian North.
Question is whether you still actively use "DG" (unslaved mode) for your compass system. Given GPS would you miss it if it were not there? (i.e. mag slaved mode only)
I've been told that folks flying to oil platforms switch to DG mode when they get close to the platform (because all that iron affects the compass). Is that true? How close do you switch?
I've also been to told guys in the Canadian north use DG mode (because of proximity of the pole makes mag slaving unworkable), and instead set the DG based on ground reference or GPS track.
The issue is that there is new technology coming into vogue that is destined to replace the old gyro systems, This technology has allowed fixed-wing aircraft to now be offered with really cheap glass cockpits. A key ingredient of the cheap system is an attitude and heading sensor that uses MEMS technology (micro electro-mechanical sensors), but the problem is that these "gyros" don't remain stable very long when they lose their slaving. As a result, most of the fixed-wing systems using this technology no longer provide a "DG" mode. Question is whether losing the DG mode is acceptable for helicopters.
I've been told that people have worked around this by flying GPS track, and that the new magnetometers are less affected by declination angle and so you don't get the attitude based compass errror in the far north like you got with the old systems.
Other people have told me that it's only the old farts who still use DG mode.
The guys flying CAPSTONE stuff in Alaska may have some opinion on this as well. Since the technology was developed for the CAPSTONE program, but is now being used in stuff like Garmin G-1000, Honeywell APEX-2000, Chelton Flight sytems, and the system on the new Eclipse (Avidyne). Given the cost and reliability of the MEMS, it will eventually displace traditional compass systems.
---- so the change is coming... is it going to be a problem???
Thanks in advance
Avnx EO
Looking for folks who operate off oil platforms or in the Canadian North.
Question is whether you still actively use "DG" (unslaved mode) for your compass system. Given GPS would you miss it if it were not there? (i.e. mag slaved mode only)
I've been told that folks flying to oil platforms switch to DG mode when they get close to the platform (because all that iron affects the compass). Is that true? How close do you switch?
I've also been to told guys in the Canadian north use DG mode (because of proximity of the pole makes mag slaving unworkable), and instead set the DG based on ground reference or GPS track.
The issue is that there is new technology coming into vogue that is destined to replace the old gyro systems, This technology has allowed fixed-wing aircraft to now be offered with really cheap glass cockpits. A key ingredient of the cheap system is an attitude and heading sensor that uses MEMS technology (micro electro-mechanical sensors), but the problem is that these "gyros" don't remain stable very long when they lose their slaving. As a result, most of the fixed-wing systems using this technology no longer provide a "DG" mode. Question is whether losing the DG mode is acceptable for helicopters.
I've been told that people have worked around this by flying GPS track, and that the new magnetometers are less affected by declination angle and so you don't get the attitude based compass errror in the far north like you got with the old systems.
Other people have told me that it's only the old farts who still use DG mode.
The guys flying CAPSTONE stuff in Alaska may have some opinion on this as well. Since the technology was developed for the CAPSTONE program, but is now being used in stuff like Garmin G-1000, Honeywell APEX-2000, Chelton Flight sytems, and the system on the new Eclipse (Avidyne). Given the cost and reliability of the MEMS, it will eventually displace traditional compass systems.
---- so the change is coming... is it going to be a problem???
Thanks in advance
Avnx EO
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Although all ships, platforms & rigs are of Metal/iron, not all influence the compasses the same way.
We had a FSO that would upset all compasses by more than 90º. Switching to DG before landing would allow a quicker reset after take-off. Some instalations would not upset the compasses at all.
If you forget to check your gyro after T/O, youd could be embarrassed when finding your self several degrees off course
We had a FSO that would upset all compasses by more than 90º. Switching to DG before landing would allow a quicker reset after take-off. Some instalations would not upset the compasses at all.
If you forget to check your gyro after T/O, youd could be embarrassed when finding your self several degrees off course
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Some pilots offshore switch to DG mode after landing, and then switch back after takeoff. Depending on the platform and how long you're there, your heading indicator can be pulled off, sometimes by much more than 45 degrees. It's a tradeoff - switch to DG and not have it pulled off, and then forget to switch it back and have it drift off over time, or leave it in slaved mode, and reslave it after takeoff. I tend to just leave it slaved, because it's hard to know how much it will be affected, and assume it will be off after takeoff. The PNF just calls out track from the GPS, and reslaves the compass once we get stabilized on a course. It's a PITA to have no idea which way you're going, especially in the dark, other than reading the track from the GPS, but we deal with it the best way we can.
That's Life!!
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On the North Sea, the compasses are set to DG as part of the 'finals' check, and reslaved as part of the 'after-take off/go-around checks'. Sitting on a heli-deck, you would sometimes notice a discrepancy between the E2 and the HSI, this could be up to 40 to 50 degrees.