Flying in snow
Never picked up any ice in snow. Let me define icing in a helicopter as picking up enough ice on the blades to register an increase in torque. Snow will build up everywhere else that it can, like the wiper blades, windshield, crosstubes, etc, but won't affect the operation of the helicopter. There are some restrictions on snow operations that require baffles or other deflectors to keep the snow away from the engine intakes but that is not an "icing" problem.
Rule of thumb is if you can see the next tree or the next powerpole you keep going, otherwise you sit and wait in a hover at said tree until you can see the next one. Heavy snowfall tends to come in showers, so if you can wait out the worst for 20-30 minutes you can carry on. If I had a concern about snow it is the variable visibility - a few feet one minute, 10 miles the next.
malabo
Rule of thumb is if you can see the next tree or the next powerpole you keep going, otherwise you sit and wait in a hover at said tree until you can see the next one. Heavy snowfall tends to come in showers, so if you can wait out the worst for 20-30 minutes you can carry on. If I had a concern about snow it is the variable visibility - a few feet one minute, 10 miles the next.
malabo
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"Rule of thumb is if you can see the next tree or the next powerpole you keep going, otherwise you sit and wait in a hover"
Increase that to about 6 poles you might be nearer the mark. And I would be on the ground, not hovering.
Scotto, if you're not in precipitation, you won't get icing, and the time to start looking out is when you have to turn the anti-icing on, which is 4 degrees or so in the 206. I seem to remember something about the 206 (in UK anyway) not being able to fly in snow anyway, but I may be wrong.
As malabo says, you may need baffles or deflectors, or even snow kits to protect the engine, depending on the machine, but dry powdery snow is otherwise not a problem for the airframe, until it starts to restrict your vis.
Wet, clingy snow won't get off the windcscreen and won't blow off in flight (downwash in the hover is best) so don't even try. Get yer backside on the ground with a coffee in your hand at the nearest hostelry first!
Phil
Increase that to about 6 poles you might be nearer the mark. And I would be on the ground, not hovering.
Scotto, if you're not in precipitation, you won't get icing, and the time to start looking out is when you have to turn the anti-icing on, which is 4 degrees or so in the 206. I seem to remember something about the 206 (in UK anyway) not being able to fly in snow anyway, but I may be wrong.
As malabo says, you may need baffles or deflectors, or even snow kits to protect the engine, depending on the machine, but dry powdery snow is otherwise not a problem for the airframe, until it starts to restrict your vis.
Wet, clingy snow won't get off the windcscreen and won't blow off in flight (downwash in the hover is best) so don't even try. Get yer backside on the ground with a coffee in your hand at the nearest hostelry first!
Phil
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Scotto,
Anytime you're flying in wet snow around freezing, as Paco says, you either want to be keeping a close eye on things, or having said coffee. That said, we do a LOT of work in these conditions on the West Coast, you just have to monitor them closely, and bear in mind an Astar will be different to a 500 or 206 etc etc. Know your flight manual and you'll be fine a far as an type specific issues/limitations.
Flying in colder, falling snow, is actually preferable to rain for me in many instances. A) It doesn't stick to the window or distort your vision as rain does, and B) you usually don't have fogging issues on the inside of the wind screen. However, and this is a really big however, in very low vis operations as Malabo is talking about, you have to be very careful about flying over open, or completely snow covered areas. This can lead to "whiteout" situations, that in a VFR ship, can and will lead to a nasty accident.
There are a few "rules of thumb" I use, but mainly when operating below the treeline, don't attempt to transit an area you cannot see across such as a frozen lake, or even open fields when the vis is right down in the one power pole example. This is a sure way to get disoriented, and leads to a number of accidents every year. Fly the edge of lakes or fields along the tree-line.
The other thing, is to be very aware of the "snowball" on approach and departure in fresh snow. This is the cause of a number of rollovers every season, and there are a few things you can do to mitigate the effects of blowing on liftoff or dept. First, ALWAYS land next to something dark in colour, a rock or bush will work, and be close, even if you land ON the bush. This is often your only point of reference. Same goes for dept, choose a dark ref point close to the machine, and maintian contact with it until you are either able to rise above the snowball, or transition forward from it. Your choice of dept will be governed by an number of things that I really can't type out at this speed....lol
I wouldn't worry about above the tree-line work right now, that's a bit further down the road for you judging by your question, But, if you do find youreself going there, make sure you've got very good weather until you get some training and more experience in those areas.
Good luck, and remember this is by no means a complete lesson on snow flying, get some training with an experienced pilot if at all possible.
RH
Anytime you're flying in wet snow around freezing, as Paco says, you either want to be keeping a close eye on things, or having said coffee. That said, we do a LOT of work in these conditions on the West Coast, you just have to monitor them closely, and bear in mind an Astar will be different to a 500 or 206 etc etc. Know your flight manual and you'll be fine a far as an type specific issues/limitations.
Flying in colder, falling snow, is actually preferable to rain for me in many instances. A) It doesn't stick to the window or distort your vision as rain does, and B) you usually don't have fogging issues on the inside of the wind screen. However, and this is a really big however, in very low vis operations as Malabo is talking about, you have to be very careful about flying over open, or completely snow covered areas. This can lead to "whiteout" situations, that in a VFR ship, can and will lead to a nasty accident.
There are a few "rules of thumb" I use, but mainly when operating below the treeline, don't attempt to transit an area you cannot see across such as a frozen lake, or even open fields when the vis is right down in the one power pole example. This is a sure way to get disoriented, and leads to a number of accidents every year. Fly the edge of lakes or fields along the tree-line.
The other thing, is to be very aware of the "snowball" on approach and departure in fresh snow. This is the cause of a number of rollovers every season, and there are a few things you can do to mitigate the effects of blowing on liftoff or dept. First, ALWAYS land next to something dark in colour, a rock or bush will work, and be close, even if you land ON the bush. This is often your only point of reference. Same goes for dept, choose a dark ref point close to the machine, and maintian contact with it until you are either able to rise above the snowball, or transition forward from it. Your choice of dept will be governed by an number of things that I really can't type out at this speed....lol
I wouldn't worry about above the tree-line work right now, that's a bit further down the road for you judging by your question, But, if you do find youreself going there, make sure you've got very good weather until you get some training and more experience in those areas.
Good luck, and remember this is by no means a complete lesson on snow flying, get some training with an experienced pilot if at all possible.
RH
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Scotto...
There's some useful info here?
http://www.caa.govt.nz/fulltext/Safe...g_Handbook.pdf
Be careful out there
...170'
There's some useful info here?
http://www.caa.govt.nz/fulltext/Safe...g_Handbook.pdf
Be careful out there
...170'
Last edited by 170'; 20th Oct 2006 at 11:23.
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"Rule of thumb is if you can see the next tree or the next powerpole you keep going, otherwise you sit and wait in a hover"
Increase that to about 6 poles you might be nearer the mark. And I would be on the ground, not hovering.
Scotto, if you're not in precipitation, you won't get icing, and the time to start looking out is when you have to turn the anti-icing on, which is 4 degrees or so in the 206. I seem to remember something about the 206 (in UK anyway) not being able to fly in snow anyway, but I may be wrong.
As malabo says, you may need baffles or deflectors, or even snow kits to protect the engine, depending on the machine, but dry powdery snow is otherwise not a problem for the airframe, until it starts to restrict your vis.
Wet, clingy snow won't get off the windcscreen and won't blow off in flight (downwash in the hover is best) so don't even try. Get yer backside on the ground with a coffee in your hand at the nearest hostelry first!
Phil
Increase that to about 6 poles you might be nearer the mark. And I would be on the ground, not hovering.
Scotto, if you're not in precipitation, you won't get icing, and the time to start looking out is when you have to turn the anti-icing on, which is 4 degrees or so in the 206. I seem to remember something about the 206 (in UK anyway) not being able to fly in snow anyway, but I may be wrong.
As malabo says, you may need baffles or deflectors, or even snow kits to protect the engine, depending on the machine, but dry powdery snow is otherwise not a problem for the airframe, until it starts to restrict your vis.
Wet, clingy snow won't get off the windcscreen and won't blow off in flight (downwash in the hover is best) so don't even try. Get yer backside on the ground with a coffee in your hand at the nearest hostelry first!
Phil
/perfrej
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I have not done a lot of flying in snow but one thing I have noticed is that thicker snow started to stick and remain on the screen at about +2°C where as rain or thin powdery snow needs a temperature of 0°C or less to stick.
Before I saw this I always thought you would have to have a tempreture of 0°C or less for snow to stick.
Before I saw this I always thought you would have to have a tempreture of 0°C or less for snow to stick.
You can fly below 4.4C (40 deg F) without the deflectors and separators (but not falling or blowing snow) but the engine anti-ice has to be on in visible moisture. Has to be off if OAT is over 4.4C. Take your pick of 4 or 5 if you've got a fancy digital thermometer in C.
For flight in falling or blowing snow you need FMS10 and 12 (particle separator and snow deflectors) installed, and then there are some limits on how long you can hover, idle, etc.
Good idea to have the Engine Automatic Re-Ignition (FMS18) installed too. It will also make a "tvarich" or true believer out of you when you're hovering over somewhere inhospitable on a dark dreary day and the little orange light tells you that it's done you a favor and relit the engine.
malabo
For flight in falling or blowing snow you need FMS10 and 12 (particle separator and snow deflectors) installed, and then there are some limits on how long you can hover, idle, etc.
Good idea to have the Engine Automatic Re-Ignition (FMS18) installed too. It will also make a "tvarich" or true believer out of you when you're hovering over somewhere inhospitable on a dark dreary day and the little orange light tells you that it's done you a favor and relit the engine.
malabo
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Thanks for your input. The BH407 I fly has the intake baffles that will be installed soon. I have flown UH-1's in Germany for three years, but I didn't fly that much in actual snowing conditions. Done plenty of whiteout training and so on. I was just wonding if snow sticking on the acft during flight would accumulate into ice. Any experience with snow melting on the acft (after you push it out of the hangar) and refreezing on it in flight.
Thanks for you input again.
S
Thanks for you input again.
S
Any experience with snow melting on the acft (after you push it out of the hangar) and refreezing on it in flight.
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False Horizon
As a result of an accident that occurred down this end of the planet over 30 years ago, a theory was developed that in whiteout conditions, the human brain will generate a false horizon when faced with a wall of white with dark objects either side.
Does this actually occur? The video below is of a standard whiteout situation in Antartica. The camera does not capture any dark objects to the left or right, but I can't see how that could make any difference re the pilot's perception of the horizon. If it isn't there, it isn't there, one would think.
Does this actually occur? The video below is of a standard whiteout situation in Antartica. The camera does not capture any dark objects to the left or right, but I can't see how that could make any difference re the pilot's perception of the horizon. If it isn't there, it isn't there, one would think.
Errr - he's flying on instruments! He has an AI to tell him where the horizon is.
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Exactly. He's on instruments, until he's almost on the runway. The pilot on the accident flight was VMC, and faced that wall of white for a whole two minutes before deciding to climb out. The excuse put forward for his not doing so immediately is the false horizon theory.
Ah I see where you are coming from now ampan.
However reviewing a video won't help you understand because you have none of the physiological factors present.
The propreoceptive feedback (seat of the pants feelings) from muscles and nerves allied with the semi-circular canals in the ears provide powerful orientation signals - the brain will interpret these (possibly erroneously) and calculate what it thinks is the local vertical and therefore where the horizon is.
However reviewing a video won't help you understand because you have none of the physiological factors present.
The propreoceptive feedback (seat of the pants feelings) from muscles and nerves allied with the semi-circular canals in the ears provide powerful orientation signals - the brain will interpret these (possibly erroneously) and calculate what it thinks is the local vertical and therefore where the horizon is.
In the accident you refer to the illusion was optical, not created within the brain. See here for some more http://www.erebus.co.nz/Portals/4/Do...Phenomenon.pdf
No, the visual perception and interpretation of what is actually there is the problem and that lies fairly and squarely within the brain. By definition any optical illusion is the brain incorrectly interpreting the visual cues.
This type of whiteout, where texture cannot be defined, is observable when skiing in flat light - you don't see the bumps until you ski into them.
'Hidden' rideglines are also a problem on NVG (it is lack of depth perception and texture information again) - I encountered it last year in the Falklands (very dark) and was saved by the rad-alt.
This type of whiteout, where texture cannot be defined, is observable when skiing in flat light - you don't see the bumps until you ski into them.
'Hidden' rideglines are also a problem on NVG (it is lack of depth perception and texture information again) - I encountered it last year in the Falklands (very dark) and was saved by the rad-alt.
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During my time as a Army Pilot as soon as the snow arrived we were rebriefed about snow landings and take-offs etc,also we had to fly with a QHI and demonsrate we could carry out this type of flying,what happens as a civilian or do you learn the hard way.