Helicopter missing after Chelsea v Liverpool match
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It very much depends on how far you are below MSA; a few feet, or even a few hundred wouldn't cause a problem, although it's surely better to stop your descent at MSA unless you are visual and are likely to remain so.
In the case in question, the helicopter was descended - perhaps visually - to 20'AGL. How do you then propose to climb safely to MSA in IMC? Entering IMC on departure from an un-surveyed site is fraught with danger (electricity pylons, telegraph poles, trees, etc). To maintain stability in the climb you need sufficient airspeed. This is why we have IMC envelopes. Even a climb at Vy at the highest ROC achievable is going to require a fair amount of distance.
I've checked my logbook, and this is an aircraft that I haven't flown, so I don't know what equipment it had, but a nightsun would have been nice. The landing lights on all the twin-squirrels that I've flown have been woefully inadequate for night departures from unfamiliar sites.
In the case in question, the helicopter was descended - perhaps visually - to 20'AGL. How do you then propose to climb safely to MSA in IMC? Entering IMC on departure from an un-surveyed site is fraught with danger (electricity pylons, telegraph poles, trees, etc). To maintain stability in the climb you need sufficient airspeed. This is why we have IMC envelopes. Even a climb at Vy at the highest ROC achievable is going to require a fair amount of distance.
I've checked my logbook, and this is an aircraft that I haven't flown, so I don't know what equipment it had, but a nightsun would have been nice. The landing lights on all the twin-squirrels that I've flown have been woefully inadequate for night departures from unfamiliar sites.
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Beater, I disagree. I fly a SPIFR aircraft in an almost identical role to that of this pilot and it seems to me a timely, properly controlled IMC climb would almost certainly have saved this aircraft. A nightsun most probably wouldn't, after all the aircraft would already have had a landing light plus a movable searchlight.
[I have used nightsun quite extensively and taught its use (RAF SH (Puma), SAR and special ops (S-76 and Blackhawk) and UK police (AS355). As Jellycopter says, it's of limited use, counterproductive even, in very poor visibility caused by low cloud and fog due to glare and backscatter. Because night vision is instantly reduced, suddenly you can see nothing outside of the beam, at least until your eyes adjust. To attempt to get it fired up and pointing in the desired direction would have increased the pilot's workload further, at least for a short time].
As far as an IMC climb to MSA goes, minimum IMC speed and full power, wings level, ball in the middle. Increase speed to Vy once at a safe altitude. Or alternatively, a Class 1 helipad departure profile. Not sure why you asked that; it's fairly basic stuff, as per any night takeoff into IMC from a remote site.
[I have used nightsun quite extensively and taught its use (RAF SH (Puma), SAR and special ops (S-76 and Blackhawk) and UK police (AS355). As Jellycopter says, it's of limited use, counterproductive even, in very poor visibility caused by low cloud and fog due to glare and backscatter. Because night vision is instantly reduced, suddenly you can see nothing outside of the beam, at least until your eyes adjust. To attempt to get it fired up and pointing in the desired direction would have increased the pilot's workload further, at least for a short time].
As far as an IMC climb to MSA goes, minimum IMC speed and full power, wings level, ball in the middle. Increase speed to Vy once at a safe altitude. Or alternatively, a Class 1 helipad departure profile. Not sure why you asked that; it's fairly basic stuff, as per any night takeoff into IMC from a remote site.
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Beater
It really is nonsense to think you need to be VMC up to MSA on a departure before going IFR I'm afraid. Of course you need to be sure of obstacles and know your surroundings before going IMC and a pilot must be aware of local obstructions and terrain before doing so. This area was about as flat as you can get, with nothing above 200ft I shouldn't think. Now if the location was somewhere hilly/moutainous be a different deal.
And also agree ShyTorque on the nightsun - it was almost certainly bumbling into patchy mist/fog at low level that caused the disorientation and LOC and with the amount of moisture in the air the glare would have just made things a lot worse. Scant ground lighting is a nightmare - a few bits can mislead into thinking vis is better than it is, then when there's none you're effectively IMC. It was probably recognition of the well lit truck yard that sucked Steve into thinking (a) he was nearly there, and (b) the vis was going to be better than it was over the last mile or two. Once that had gone.... Tragic lesson for us all.
Sadly this was not unlike a B206 accident near Goodwood many years ago. Someone will remember the details - although in that case it was trying to sneak over the South Downs that was the final problem.
It really is nonsense to think you need to be VMC up to MSA on a departure before going IFR I'm afraid. Of course you need to be sure of obstacles and know your surroundings before going IMC and a pilot must be aware of local obstructions and terrain before doing so. This area was about as flat as you can get, with nothing above 200ft I shouldn't think. Now if the location was somewhere hilly/moutainous be a different deal.
And also agree ShyTorque on the nightsun - it was almost certainly bumbling into patchy mist/fog at low level that caused the disorientation and LOC and with the amount of moisture in the air the glare would have just made things a lot worse. Scant ground lighting is a nightmare - a few bits can mislead into thinking vis is better than it is, then when there's none you're effectively IMC. It was probably recognition of the well lit truck yard that sucked Steve into thinking (a) he was nearly there, and (b) the vis was going to be better than it was over the last mile or two. Once that had gone.... Tragic lesson for us all.
Sadly this was not unlike a B206 accident near Goodwood many years ago. Someone will remember the details - although in that case it was trying to sneak over the South Downs that was the final problem.
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We will probably have to agree to disagree about this.
I too have used nightsun in some of the roles mentioned by ST, but let's not turn this into a 'my dad's bigger than your dad' type argument. In fact we probably would do well to disregard the nightsun arguments (yes, I know that I first mentioned it). But just to clarify things, my point was that I would prefer to have sufficient illumination to be able to see and avoid any obstacles on my departure path. I don't find that night vision is of much use. How many of us prepare for a night flight by sitting open-eyed in a dark room? Personally, I walk from a well lit briefing room to a well lit heli-pad and then depart from there using the landing light. I have even been known to use the storm light to complete paperwork. For a VMC departure I would like as much light outside as possible; in the event that I was blinded by the landing light/nightsun reflecting off fog, then that makes the go/no go decision easy. Once IMC I'm not interested in having night vision, as however good it is you can't see anything anyway. I now require adequately lit instruments.
Mention is made of a departure using min IMC speed and max power.
Why would you comply with the min IMC speed and yet still put yourself outside the IMC envelope by using an excessive ROC? This would still lead to reduced stability and an increased risk of loss of control. Could this ring any bells? And could you see pylons, let alone wires using only your night vision and/or a landing light. You are still going to be moving forwards into the unknown.
OK, it's time to make a confession...
I'm not an expert on night-time departures from unsurveyed sites/helipads. In fact I've never done one yet. I've spent a lot of hours low level using nightsun but I've never landed or taken off from an off-arifield site at night that I was not familiar with. I'm surprised that this is apparently considered normal in the corporate night-flying world. Having said that, I recently spoke to a friend flying corporate that informed me that they routinely let down in IMC to 300' AGL to private landing sites.
No thanks!
Respect to you guys. If I'd managed to get into the situation described I wouldn't have had the bottle to do anything other than to use my degraded night vision to gropingly tie down and call it a night.
I too have used nightsun in some of the roles mentioned by ST, but let's not turn this into a 'my dad's bigger than your dad' type argument. In fact we probably would do well to disregard the nightsun arguments (yes, I know that I first mentioned it). But just to clarify things, my point was that I would prefer to have sufficient illumination to be able to see and avoid any obstacles on my departure path. I don't find that night vision is of much use. How many of us prepare for a night flight by sitting open-eyed in a dark room? Personally, I walk from a well lit briefing room to a well lit heli-pad and then depart from there using the landing light. I have even been known to use the storm light to complete paperwork. For a VMC departure I would like as much light outside as possible; in the event that I was blinded by the landing light/nightsun reflecting off fog, then that makes the go/no go decision easy. Once IMC I'm not interested in having night vision, as however good it is you can't see anything anyway. I now require adequately lit instruments.
Mention is made of a departure using min IMC speed and max power.
Why would you comply with the min IMC speed and yet still put yourself outside the IMC envelope by using an excessive ROC? This would still lead to reduced stability and an increased risk of loss of control. Could this ring any bells? And could you see pylons, let alone wires using only your night vision and/or a landing light. You are still going to be moving forwards into the unknown.
OK, it's time to make a confession...
I'm not an expert on night-time departures from unsurveyed sites/helipads. In fact I've never done one yet. I've spent a lot of hours low level using nightsun but I've never landed or taken off from an off-arifield site at night that I was not familiar with. I'm surprised that this is apparently considered normal in the corporate night-flying world. Having said that, I recently spoke to a friend flying corporate that informed me that they routinely let down in IMC to 300' AGL to private landing sites.
No thanks!
Respect to you guys. If I'd managed to get into the situation described I wouldn't have had the bottle to do anything other than to use my degraded night vision to gropingly tie down and call it a night.
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Rotorspeed.
Our posts crossed, but you mention that it is nonsense to remain VMC up to MSA provided you are aware of obstacles and the surrounding area. This is exactly what I'm getting at! Do you know of every obstruction including power-lines within 2 miles of your house? You say that the area is flat with nothing above 200' you shouldn't think. Shouldn't think! I would like more certainty than a 'shouldn't think'. Besides which, it is possible that you could hit something lower than 200'. Trees, perhaps?
You mention that his recognising the yard would lead him to think that he was nearly there. If he recognised the yard he would have known that he was nearly there. I mentioned the problem that this causes on my first post on this thread.
'Tragic lesson for us all'.
Only if we learn something from it.
Our posts crossed, but you mention that it is nonsense to remain VMC up to MSA provided you are aware of obstacles and the surrounding area. This is exactly what I'm getting at! Do you know of every obstruction including power-lines within 2 miles of your house? You say that the area is flat with nothing above 200' you shouldn't think. Shouldn't think! I would like more certainty than a 'shouldn't think'. Besides which, it is possible that you could hit something lower than 200'. Trees, perhaps?
You mention that his recognising the yard would lead him to think that he was nearly there. If he recognised the yard he would have known that he was nearly there. I mentioned the problem that this causes on my first post on this thread.
'Tragic lesson for us all'.
Only if we learn something from it.
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Oh for goodness sake beater this is getting tedious. If I was actually making the flight in question of course I would have checked on obstructions for sure - I only said "shouldn't think" because I'd not looked at a bloody chart before posting and was commenting as a third party!
And yes I do know of every obstruction within 2 miles of my house. It's not difficult.
And yes I do know of every obstruction within 2 miles of my house. It's not difficult.
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Why would you comply with the min IMC speed and yet still put yourself outside the IMC envelope by using an excessive ROC? This would still lead to reduced stability and an increased risk of loss of control.
Presumably he was somewhat familar with the area around the proposed LS (because he had been there before by day) so he should have had some idea of the major obstructions. If the aircraft had been climbed asap after realising that the perceived lights were incorrect, the outcome would not have been the same. There have been nights when I too have had to go around from low level because the weather wasn't as good as predicted or low level fog was created by the presence of the aircraft's rotorwash. Sometimes a published IMC max. rate of climb is not a priority. Yes, I've had to go around from 300 feet radalt by night, but only on a known letdown path, on a stabilised approach. What I didn't do was attempt to go "grobbling around" in the dark at low level in marginal weather from position uncertain.
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Some times it's a pleasure to fly at night and the view to the east was great. The moon was shining on this low carpet of cloud as far as the eye could see, I thought that night, "glad I'm not going that way".
or low level fog was created by the presence of the aircraft's rotorwash
Just a quick query having followed the thread from day one, and being a Qualified Met observer, how would the above occur? Is it the low cloud in effect being blown down to the surface, or more technical than that? Interesting to me as I've never heard of the phenomena, though I am aware of the problems of heli's disturbing snow when landing.
Ta in advance ...
Just a quick query having followed the thread from day one, and being a Qualified Met observer, how would the above occur? Is it the low cloud in effect being blown down to the surface, or more technical than that? Interesting to me as I've never heard of the phenomena, though I am aware of the problems of heli's disturbing snow when landing.
Ta in advance ...
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It's a very localised, almost personal fog that sometimes comes off the vortices caused by the rotor wash, in conditions of very high relative humidity. It disperses almost immediately once the aircraft has passed but as far as the pilot is concerned, the visibility drops to about the same as the rotor blade length.
Once had an HS125 envelop the whole of the runway and short finals in front of me into fog. I was following about 3 miles behind in a Puma. Conditions were clear starry night, 100% RH but no wind so therefore no mixing = no fog. The HS 125 provided the mixing and instantly the fog began to form and although I had the required visual referneces at decision height, when we got down to the runway we could only see one runway light ahead of us. I had to use the GPS to locate the turn off!
Also started up a Wessex at Valley early one morning in very similar conditions. The effect of the rotor disturbing the crisp, clear air was to fog out the whole of the dispersal area so that we could no longer see where to taxi. It took several hours to clear.
Beater, to quote VeeAny - you don't know what you don't know.
JJ
Also started up a Wessex at Valley early one morning in very similar conditions. The effect of the rotor disturbing the crisp, clear air was to fog out the whole of the dispersal area so that we could no longer see where to taxi. It took several hours to clear.
Beater, to quote VeeAny - you don't know what you don't know.
JJ
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It also has a distinctive odour. I can smell it now.
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I couldn't agree more. In fact, I would go as far as to say that there are known knowns. There are things we know we know. We also know there are known unknowns. That is to say we know there are some things we do not know. But there are also unknown unknowns, the ones we don't know we don't know. And you can quote me on that.
Are Jellycopter and Shy Torque in anyway related? I'm only asking because they both seem to have experienced phenomena that seems uncommon.
Has anyone else experienced anything like this?
There must be a photo out there somewhere.
Anyway, back to the matter in hand. Fog.
Radiation
Advection
Hill
Coastal
Steam
Freezing
And of course, the spooky one that I've yet to see. Shall I call it 'rotor induced fog' or does it go by another name? And is the one that lasts for hours caused by a subtle difference in rotor wash to the one that disperses almost immediately?
Can anyone else add to the list?
Serious answers only, please.
Are Jellycopter and Shy Torque in anyway related? I'm only asking because they both seem to have experienced phenomena that seems uncommon.
Has anyone else experienced anything like this?
There must be a photo out there somewhere.
Anyway, back to the matter in hand. Fog.
Radiation
Advection
Hill
Coastal
Steam
Freezing
And of course, the spooky one that I've yet to see. Shall I call it 'rotor induced fog' or does it go by another name? And is the one that lasts for hours caused by a subtle difference in rotor wash to the one that disperses almost immediately?
Can anyone else add to the list?
Serious answers only, please.
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Posts crossed again. But good one ST. I think that must have been it.
Breakfast of Cherryade, sprouts (well done), spinach and overripe camembert. Hope I don't experience it today!
Breakfast of Cherryade, sprouts (well done), spinach and overripe camembert. Hope I don't experience it today!
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Beater;
Rotor induced fog is quite well known. I once put Aberdeen into low viz procedures doing a ground run before the first departure of the day. The Puma enveloped itself in a small fog bank which then spread as others started up. Took ten minutes to cover the entire airfield. Landing last week in clear, humid conditions the viz was appalling for five minutes after I landed.
Watch your tip vortices in the right conditions and you will see the phenomina.
VH
Rotor induced fog is quite well known. I once put Aberdeen into low viz procedures doing a ground run before the first departure of the day. The Puma enveloped itself in a small fog bank which then spread as others started up. Took ten minutes to cover the entire airfield. Landing last week in clear, humid conditions the viz was appalling for five minutes after I landed.
Watch your tip vortices in the right conditions and you will see the phenomina.
VH
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Fair enough. Just haven't experienced it myself.
We live and learn.
We live and learn.
Last edited by the beater; 18th Nov 2008 at 09:30. Reason: Just to add that I've just googled rotor induced fog and the only result I found was my own post!
Beater
I'm no met man but it's basically Radiation Fog. As I understand it, it is that in order for water vapour to condense into a water droplet there needs to be a condensation nucleus. This can be anything from the aircraft itself down to microscopic pollution particles. In the case of 'rotor induced fog' the air has to be very still. The air cools overnight through radiation but because there is no movement in the air there is no mixing and therefore there are no 'collisions' with condensation nuclei and fog does not form despite 100 per cent Relative Humidity. What will be experienced however, is a very heavy dew. Now along comes ****ehawk with his helicopter and not only does he stir up the air but he's also producing quite a lot of exhaust efflux (condensation nuclei) and hey presto - Radiation Fog!
JJ
I'm no met man but it's basically Radiation Fog. As I understand it, it is that in order for water vapour to condense into a water droplet there needs to be a condensation nucleus. This can be anything from the aircraft itself down to microscopic pollution particles. In the case of 'rotor induced fog' the air has to be very still. The air cools overnight through radiation but because there is no movement in the air there is no mixing and therefore there are no 'collisions' with condensation nuclei and fog does not form despite 100 per cent Relative Humidity. What will be experienced however, is a very heavy dew. Now along comes ****ehawk with his helicopter and not only does he stir up the air but he's also producing quite a lot of exhaust efflux (condensation nuclei) and hey presto - Radiation Fog!
JJ
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Now along comes ****ehawk with his helicopter and not only does he stir up the air but he's also producing quite a lot of exhaust efflux
Are Jellycopter and Shy Torque in anyway related? I'm only asking because they both seem to have experienced phenomena that seems uncommon.
No, I'm not related to Jellycopter, but he and I flew together at one time. Albeit not since mid August 1987 when I claimed to have taught him something in a Puma. My old logbook gives no useful clue what it was but it took two hours, possibly something about low-level nav.
Ever noticed the condensed water vapour from wing tip vortices as a jet aircraft pulls hard in a display during very humid conditions? This rotor induced fog is the same thing as far as I can see. The vortices at the rotor tips cause the formation of a foggy "curtain". It's not common but I've seen it a number of times at the bottom of an IMC approach to field locations. Worst time though was at Kai Tak airport during a period of extremely heavy showers. I was asked to hover taxy across the runway and hold but shortly after crossing we began to go IMC in the hover. I had to carry out a very expeditious zero speed landing using the only ground reference available on the airfield, which was the edge of some tarmac, off to my right. After landing on, ATC asked me to confirm my location and I couldn't give it for a few minutes because we were IMC on the ground. When it suddenly cleared, we were just outside the Fire section.
Last edited by ShyTorque; 18th Nov 2008 at 14:07.