Downwind Approaches
 

Can I lean on all your experiences and ask what is the correct technique for approaching confined areas downwind if there is no way of approaching into wind.

I guess this comes down to the advanced techniques. What are your experiences.

Thanks

Watch out for vortex ring; it's easy to have a high rate of descent at low airspeed if you fly the apparent closure rates you're used to for in-to-wind ops.
Make sure you've got OGE hover capability because there will be a bigger gap between loss of translational lift and any assistance from ground effect.
Slow down fairly early ground-speed wise so you don't get sucked in to racing into a confined area at a million knots.
That's about it off the top of my head.

I think the previous post covers it well. Going in slowly (groundspeed) is important as you won't want to end up trying to lose a lot of speed very quickly, but watch vortex ring / settling with power.

Also think careful about the speed of the wind, as you could easily end up deep in the wrong area of the avoid curve. It makes it naturally more risky, and so you need to balance that up with the need for going in there. If the space is tight and the wind is strong, then going in downwind may not be approprate and a different spot may a better choice.

R

If you must, but be prepared to throw it away a lot earlier

phil

I concur with all the above.

Just like to add the following:

To avoid the excess ROD with low IAS, make it a shallow approach. This unfortunately means you will be hanging on the power earlier so have an escape route if possible.

Is a curving approach possible?

If possible, get the aircraft into wind for the final descent into the confined area and obviously for the departure if you can do it, although the wind might not be the over-riding factor. Think about the best / shortest way out to get translational lift, before you go in!

Be prepared to throw away the landing all together and come back on a day with more favourable wind or all up weight (or you may not come back at all). :)

Chitchat,
There is a fallacy about helicopters being able to do everything. We're certainly more flexible than the fix-wing guys and I guess thats why it's rewarding.
An aeroplane pilot has charts and graphs to accept or decline a tailwind component on his runway, and many a time they'll say no due to performance limitatations.
You lucky b....... has quite often have to make that decision by arriving in the middle of nowhere, with one way in and one way out (that's why they asked for a helicopter).
On jobs I've been on before, the guys who have damaged themselves or the equipment or been very scared taking off or landing, have 99% of the time been heavy. I think most of them knew the machines pretty well and all it came down to was a lack of judgement , probably on a routine job.
The previous replies have all said how it should be done, and that is the way to do it. However, always make sure you're comfortable, or take someone else along who's done it and bail out when he starts twittering.:cool:

Downwind
 

What everyone has said is good advice. Obviously you are going in downwind due lack of choice. You cant look up any performance figures for downwind approaches but check on the helicopter's downwind and cross wind limits, also make sure you are not nose heavy. I once had problems at 4000 feet in a nose heavy downwind approach in a 206; couldn't stop the forward movement, most embarasing! Also try a practise approach in an unrestricted area at various weights.

Thanks to everyone.

I guess the upshot is:

Adequate power margin
Plan escape route
Shadow descent
Low rate of descent once you are committed to going in.

The one added benefit if the wind doesn't change is that when you take-off you will be going into wind :)

Downwind approaches
 

Here's a question for you more experienced rotary types, whether private or commercial...

I write as a PPL(H) with about 120 hours on the R22. In my perambulations around SE England, I have been given a few weird and wonderful approach and departure directions to/from various airfields. One of my first ever post-PPL solo trips presented me with a completely downwind approach into a grass field that left me wishing I'd been more authoritative and refused it. These days, a couple of years down the line, if I am given an approach that puts me in what I consider to be an unsafe situation, I decline and ask to join the circuit instead (or request it at the briefing stage over the phone, which I've found often works). I'm not sure whether this is done to keep helis away from the fixed wing circuits, due to differences in speed and climb/descent angles, or to allow helicopters quicker approaches or departures from the field.

Just recently I have watched helicopters at a number of airports carrying out downwind departures and arrivals. So, the question is, am I over reacting and should I accept out-of-wind ops, or am I right to request a change? And have any more of you inexperienced types found the same thing?

What are your opinions folks?

DBChopper
:confused:

Factors to bear in mind on a downwind approach below.
In practice I think downwind approaches are ok as long as you can run on a long way if no room to turn, but mostly I just turn it into wind at the end and try to keep 30 kts or so in the turn.

I think as long as you know you are downwind and have a plan as to what you will do, then dont be unduly concerned about them

Factors :-
500’ slower approach maybe 50 kts or so
Shallow Approach / Extended Approach
Gentle Inputs
High Groundspeed / Low Airspeed
Early Loss Of Translational Lift
Establish Low Hover (Run on if Necessary)

Go Around if:
High Power Settings on Approach
Directional Instabilty Excessive
High Rate of Descent

Last year Transport Canada's helicopter safety magazine published a few tips. Landing downwind was one of them. With the editor's permission (you'll grant me that won't you CTD ??;) )I'll quote it here.

Cheers

With a low time pilot, downwind approaches should in my opinion NOT be attempted if the wind is over 10 Knts, and then be done so carefully as to remind you not to do it again, your problem is one of stick authority, you will run out of it if you are not very careful,

then what do you do!!


Untill that machine fits you like a glove and vice versa you will be better alway having the wind in you face,:ok:

Thanks Randy-g
 

Thanks for posting that. That little tid-bit may prevent me from balling one up in the future. Good stuff!

As with most everything associated with helicopter flying, there is no simple answer to the question: Are downwind landings safe? There are just too many variables to make blanket statements.

But what are we really asking? Are we merely looking for reasons to justify landing downwind rather than exploring options that might take more technique?

Remember a couple of things:
1) A downwind approach could very easily mean a downwind autorotation if the engine picks that time to quit. Is that a big risk? Me, I haven't practiced any "for real" touchdown autos from inside the H-V curve. Your mileage may vary.

2) A downwind approach will certainly require more power to stop at the bottom, and there will be the real possibility that there won't be enough power, which will then require a run-on landing. The amount of risk here is dependant on how heavy you are, how high the wind speed is, and how big, flat and level the LZ is. Is there room to run it on? Can you run it on without rolling it over?

Let's look first at off-airport site landings. If I arrive at a site landing and find that all into-the-wind or crosswind approaches are blocked by a ring of orphanages, churches hearing Mass, chicken coops with irate, hat-wielding farmers and thatched-roof circumcision clinics, leaving my ONLY selection as a directly-downwind approach, I might decide that I don't really need to be landing there that day. If there was some urgency the compelled me to land, I'd consider the above risks very carefully. Then I'd follow the procedures outlined in that Transport Canada article, which is very good.

But philosophically, I'd weigh the risk of landing downwind with the risk of a very steep into-the-wind (or crosswind) approach, if one was indeed possible at all. Few site landings are so bad that you absolutely, positively cannot get in from some other azimuth than straight downwind. And of course helicopters have infinitely variable approach speeds, paths and angles. I'd use me noggin' and try to come up with an alternative. There is usually more than one single way to make an approach. I'd explore all possibilities before settling on "directly downwind."

The good news is that if you have a site that only allows a downwind landing, that'll usually mean that your take-off will be into the wind. That's good.

Finally, recognize that when you're making a downwind landing to an off-airport site, there'll come a time when a go-around is impossible. And that time might be pretty high up the approach. Once you fall back below ETL you are HOGE at high power. Sure, you might have enough excess power to initiate a go-around, but you'll surely lose altitude as you try to regain forward ETL, and your downwind angle of climb will not be impressive. How tall are those obstacles around your LZ?

So much for off-airport. What happens if you arrive at an airport and the Tower guy directs you to land downwind? Well, controllers do forget or sometimes neglect that we helicopters need to land into the wind just like the planks. Remember, our radios are transceivers. We can talk back to them, too. A gentle reminder might do the trick. "Umm, say there old bean, doing it that way will put me directly downwind. Might we come up with something else?" In my experience, this will elicit a response of "Do whatever you need to do, just remain clear of..." whatever.

No controller will force you to land downwind (unless the winds are really, really light). Even so, landing downwind to a taxiway is usually no big deal (let's just not make a habit of it). Oh, and don't expect me to always be able to do that to a small, congested non-movement area.

This of course presumes that prior to entering the traffic pattern you have visualised the airport layout, the buildings, the wind and where the Tower will likely have you land. If you have not done this, then you have not done your flight-planning properly. Remember, it's NOT GOOD ENOUGH to show up at the field boundary and be told to do something unwise, and then do it simply because you "didn't have time" to come up with another plan.

Helicopter pilots must be masters of improvisation. We make it up as we go along. Plan all you want, but there's always something that comes along to mess with you. So you have to be ready.

Any other simple questions?

DBChopper,

ATCOs tend to think that helicopters can do anything, not realising that low hours helicopter pilots can't do everything. Why land downwind at an airfield, unless you want the practice? It's harder and more dangerous, for all the reasons given. But ATC probably don't know that. I tend to phone up first, and ask if they have special procedures for helicopters. If not, I ask for what I want to do. I prefer not to join the f/w circuit, since R22s are slower than most f/w aircraft, and we slow down before we land. But if you explain in advance, you'll often get what you want, or at least know what's expected.

I learned this the hard way too. Heading for a fly-in to a busy airfield, I could hear that the circuit was crowded, and see where I wanted to land, straight into wind. I asked, and an obviously stressed FISO asked me to join the circuit like everyone else, as they were busy. I finally managed to explain that I was a helicopter, I didn't need a runway, and what I'd asked for would keep me well out of the way. He agreed. So bmuch so, that when I came to leave, he wanted me to depart the same way, now with a 25kt tailwind. :eek: I refused, and explained why. But you see, someone with more experience than I had then might have agreed, so how was he to know?

Many thanks for some very informative posts so far folks.

Whirly, with the little more experience I now have I take your approach, phone first, explain and, if necessary, re-negotiate over the radio.

Camp Freddie, Randy G and Pprune Fan #1, I shall be printing your posts off to inwardly digest!

:ok:

RDRickster No worries. :)

Obviously we should try to approach into wind, it is the safest, and easiest way to approach. If you are flying into airports all of the time, then there usually are no reasons to approach downwind. However, as pilots we need to evaluate all of our options, and decide on the safest way to conclude each flight.

For instance; if the choice is between a very steep/nearly vertical descent from +150', or a shallow downwind approach, I may decide that a downwind (or cross-wind) approach is safer. Assuming that I have the power margin, and that the wind is below the a/c's demonstrated limits. The safest route in, may not be straight into wind.

In the job that I do, terrain sometimes leaves me with few choices in the direction of approach or landing. Prior to your flights, you should check the performance charts prior to firing up, to determine weight and alt that you can HOGEwith the expected temps. This is essential when flying power limited a/c (like R22, B206, 204, etc). Once you lift off, see what power is required to HOGE, and see if it matches what the manual predicted. You did calculate your weight I hope, so you'll be able to make a meaningful comparison ??

The rule of thumb I use is; if the a/c can hover OGE with less than MCP, then I should have enough power for any hover OGE, downwind hover (in case we have to perfom hover-exits), or a landing downwind, assuming we're not power limited due to temp/alt, and I'm operating at a similar or lower altitude.

Cheers

Downwind Approaches
 

That's a tricky question actually. In common practice, all other risks being equal, take the approach into the wind. Your job as a pilot is mostly about risk management. A traffic pattern at an airport should never place you downwind just for the controllers convenience. You are accepting additional risk with no benefit.

The reason the question is tricky, though, is this. I advocate becoming skilled at downwind approaches. I actually think it should be part of the curriculum. Learn to recognize the signs of a downwind condition, (faster than normal closure rate, further aft cyclic position, changing power demands, etc.) and how to safely execute the approach or perform a go around. At some point, whether you're prepared or not, you'll find yourself in a downwind condition, even if you've read the wind perfectly just moments before. It's best to practice downwind approaches under controlled conditions and become proficient. If you don't feel comfortable doing this on your own, book some tiime with an instructor and practice approaches with the wind at various points around the azimuth. You'll make yourself a far more proficient pilot. Good luck

Inthegreen

Are downwind approaches not in the FAA syllabus for the PPL(H) ?

They are covered in the JAA license, but I find that they are rarely taught well or given the right emphasis - the student is usually given a demo and then told to avoid them, which really doesn't help them in their future operations.

If downwind approaches are not part of the FAA syllabus, how do the students acquire the skills and knowledge required to perate safely if circumstances require a downwind approach ?

:)

Head Bolt asked:Well...circumstances should never "require" a downwind approach. And students (i.e. candidates for a Private certificate) shouldn't be taught those "skills." That should be obvious.

Downwind approaches are an advanced technique. They are not "as safe" as an into-the-wind approach. Nor are they even "safe" on their own. Just the opposite; they are extremely risky. And we should not minimize that risk by the casual admission that downwind approaches are "just sometimes necessary." Not all of us feel that way. I will do everything in my power to avoid a downwind approach. (Of course, the aircraft I fly has a strong weathervaning tendency which complicates the termination of a downwind landing, especially if a run-on is required.)

For the FAA to include and recommend them, it would be tantamount to endorsing downwind approaches as an acceptable procedure. And there is no way they're going to do that - just as there is no way that they'd approve teaching "no-flare" autos. Sure, such an auto can be done, but is it safe? And would you want to teach a low-time student to do a no-flare auto? I don't think so. As with downwind landings, there are just too many variables. The FAA's attitude has always been that the safest aircraft is one that does not fly. If it's not safe, then just don't do it. To the FAA, it really is as simple as that.

The trouble is, helicopters don't fly within the confines of a book. They fly out there in the real world, where the helicopter pilot is sometimes faced with conditions that are not ideal. The amount of challenge each pilot accepts will vary, depending on his own perceived skill level, knowlege and guts. Even at my advanced hour level, there have been situations in which something was asked of me and I've said, "Not today, guys. At least, not with me at the controls." The task may not have been all that difficult, and another pilot might have attempted it willingly.

But looking back over the years, I've heard about many, many accidents. And of those that did not involve the aircraft simply coming apart, my first question was almost always, "Where was the wind?" The direction of the wind is critical to safe helicopter flying. Operating with it on your tail is something that must be done very cautiously, and by pilots who are well acquainted with the hazards and risks. In other words, not students.

DBChopper, I am surprised that your training school didn't expose you to downwind operations during the course of your training. It is good to see you are trying to learn more and erring on the side of safety with regard to them. I would recommend that you book in with an experienced instructor and do some.

Considerations with downwind approaches:

Only do them when you have to.

Make sure you are not out of your depth for your level of experience.

You must have HOGE power available.

Prioritise your potential hazards. Of course you should have a planned course of action should the engine fail as PPRUNE FAN #1 mentioned. However, the chances of the engine failing are extremely remote compared to you putting it into a vortex ring state or overpitching it due to insufficient power available. It is not much good finding yourself in VRS because you have flown a downwind profile to suit the remote possibility of an engine failure.

The R22 flight manual stipulates hover controllability has been demonstrated up to 17KTS from any direction. (This may have legal/insurance implications should something go wrong above 17KT)


The technique I used to teach was this:

Is it the only way?

Do a power check to ensure you have sufficient power available.

Make your approach angle on the shallower side of normal to ensure your ROD during the approach is manageable, and definitely no more than what you would have during a normal approach.

Keep the GROUNDSPEED during the approach comfortable and slightly slower than what you would have during a normal approach.

Regularly assess your airspeed versus your groundspeed during the approach, to determine if the downwind component is excessive AND to anticipate the loss of translational lift. Be aware that as you come out of translational lift the aircraft will want to sink out, and that sink if you let it happen may be all that it takes to bring about the onset of VRS. Anticipate the sink and don't let it happen.

If at any stage it feels too fast or doesn't feel right, initiate maximum power and go around.


I don't think downwind approaches are "extremely risky" or always unsafe as PPRUNE FAN#1 describes. Provided you are:

Not operating the aircraft beyond its limits,
Not beyond your own personal limits and level of experience,
Aware of the potential risks and how to avoid them.

You should be able to safely do one if you need to.

The Coyote,

I thought about it before posting originally, but I don't remember doing any downwind operations during my PPL(H) training. It was done at a large airfield with marked helistrips, so some was done with a slight crosswind but that was it. That's propbably why it took me by surprise, as a new boy, on those initial post-PPL cross-countries when I was given out of wind approaches. I take your point about practice and I will book some time with an instructor to have a proper play. Thanks for the post.

A sure sign of senility is the belief that everything is really just a repeat. That being said, this whole thread is remarkably like:

http://www.pprune.org/forums/showthr...light=downwind

As I posted in the past, downwind is not a horrible, deathly, stupid thing to do, in fact, under some cirumstances it is the only thing to do, and modern helicopters are designed to do it well. Attack helicopters, rescue helicopters and others need excellent power margins and powerful yaw control because they regularly fly, approach and hover downwind.
Here is a simple poster that says it all:

http://safety.army.mil/pages/media/pubs/ff/windsock.pdf

This does not mean that a PPH should run right out and start the habit, just that he/she should appreciate that many things called gospel in early years (don't play with electricity, don't cross the street, don't kiss girls) are artifacts of the restricted world of the newly initiated.

Anything downwind is not a part of the FAA CPL curriculum, which is ridiculous. Some schools teach them anyway but I actually left one that didn't. It's like not doing autos because "it's not a part of the normal procedure".

What are the recommendations in regards to downwind take-offs?

I did them for my PPL(H). I was told it was an advanced exercise to learn control of the helicopter, and to understand what was happening, NOT something that I should do. I think this is essential.

Maybe you should consider the following story. As a fairly low hours PPL(H), I flew into a friends large-ish field. There was very little wind, but what there was, was a bit gusty and changing direction a lot. He had a windsock in the field, and I approached what appeared to be into wind. He was talking to me on a handheld radio, and as I reached about 200 ft, he said; "Be careful; you've got a tailwind". Well the wind was all of about 6 or 7 knots, so I made sure I had a low rate of descent, and lots of room since my groundspeed would be higher than my airspeed, and it was no problem. Hardly a really difficult situation, I'm sure you'll all agree, even for a low hours pilot. For a TRAINED low hours pilot, that is! But for one with NO training at all as to what the situation meant, and what could happen....

PPRUNE Fan#1

I asked a genuine question re : the FAA syllabus because I did not know whether downwind approaches were included in the training regime. I gather that they are not from the various posts from DBChopper etc., and so I was surprised by your 'it should be obvious' quote.

I cannot agree with you that downwind approaches should never be required because of circumstances - and from the posts others don't agree with you either.

It is a fact of helicopter flying that downwind approaches may be required, and indeed are sometimes the only option possible.

To quote you, 'that should be obvious ......'

Fly safely all

Loose Head Bolt:Downwind approaches..."required," eh? So that is a FACT, eh? Hmm. Let's see, 10,000+ hours as a commercial helicopter pilot, and I can count on one hand the number of times a downwind approach has been "required" of me. I'm thinking back now...you know, it's hard to keep track of every single landing when you've logged more than 60,000 of them. But I'm really trying to recall a time when I was forced to land downwind without being able to find a suitable and safer alternative.

Nope, can't do it.

I must've lead a very sheltered life as a pilot, eh what! Or...maybe I'm just creative enough to figure out how to keep myself from doing something really, really stupid. And Head Bolt, when they're PAYING you to fly, you have to take it seriously and be more responsible than saying dumb things like "it is a fact that downwind approaches are sometimes required." Such a premise seems awfully immature.

I have had some rather extreme and weird and exciting crosswinds (you know, times when I've circled overhead whilst trying to decide whether it would be better to take the left or right crosswind on the way in, depending on what would happen at the bottom). But when you're downwind, your margins are extremely thin, perhaps nonexistent.

But me...see, I would take a nearly-vertical, between-the-pedals-steep approach into the wind rather than land directly downwind. Especially if I was heavy and most especially if the wind was strong. I don't like downwind; I don't mind steep. I think the risks of a very steep into-the-wind approach are far less than doing it downwind. Steep and into the wind, I can control the ship better. Downwind, you never know when the shudder you're feeling is simply the rotor going in and out of ETL or the onset of VRS. Again, your mileage may vary.

Methinks that Head Bolt and others ought to rethink their "approach" to safety. It's basically pretty simple. There is no reason to think that a downwind landing should in FACT ever be "required"...unless you're doing something where people are shooting at you.

That should be obvious.

Now watch, tomorrow I'll go out and have to land someplace downwind and end up eating all of these delicious words. But I kind of doubt it ;)

I see no real problem with landing downwind as such - it's a tool at our disposal that is low on the list, that's all. Nobody's forcing anyone to land into wind, either, but you can still get the job done as long as you realise what you're doing, as someone mentioned before. Having said that, it should not be attempted without being taught properly - it was standard on my Army course.

Faced with a vertical climb over trees to stay into wind, or clear access (especially for emergency vehicles) and a downwind takoff, I have often chosen the latter. Sometimes you have no choice on a log pad hanging off the side of a mountain - just make sure you ain't heavy and you have an escape route

phil

Shortly after getting my PPL I flew into a small airfield down south. The R/T gave the wind direction as from the south and the runway in use 32.

I thought this was a bit odd, decided I'd rather go with the wind direction and stated I'd be making my approach from the north. To which the guy said "no problem" and the approach and landing went safely, into wind, on 14.

Once on the ground it was obvious that 32 had a very noticeable upslope. With a light tailwind I guess this was still the best choice for fixed wings - but as we all know, helicopters fly differently than aeroplanes.

In this case, the guy was happy for me to choose the approach I wanted - so don't be afraid to ask for the approach you want rather than the one you are given.

Pprune No#1

C'mon now, surely you're not that inflexible?
Everyone who flies helos for a profession, knows that a downwind landing is always available, should the need arise. Provided one takes charge of the situation, they are not procedures one should shy away from.

I have done a fair number of downwind approaches to land whilst tasked on EMS; why? because there is no-where else to land - plain and simple. Do I cancel the landing because there is no other alternative, of course not.

One of the benefits of a helo is that it is versatile in this instance. If a pilot knows their limits and operates cautiously then there is absolutely no reason NOT to employ a downwind landing...WHEN THERE IS NO ALTERNATIVE (there's the rub).

Try it some time...you'll be amazed...

kissmysquirrel,

One technique I use for a downwind departure, if you have a wee bit of room. Hover into wind, as you lower the nose to accelerate and begin to move (into wind), progressively begin to turn downwind and continue to lower the nose and accelerate throughout the turn downwind. You will be through translational lift prior to being downwind and away you go. Of course your groundspeed is fast as you accelerate and turn downwind. In a light helicopter you maybe only need 20m in front of you and about 50-75m out to the side you are turning.

A direct downwind departure, just be prepared for it to sink out as you accelerate, catch up with the wind and come out of translational lift. Be ready on the power and dont let it sink. You will have a pretty quick groundspeed (maybe 10-15KT + the tailwind) before you regain translational lift as you 'come out the other side'.

Don't forget the climb gradient is not as good and you need more distance for obstacle clearance, as Nick Lappos previously pointed out.

PPF#1

Wow, 10,000 hours eh - you'd be a low-time pilot on my operation, (average hours 12,000+) where we have to carry out downwind approaches on a regular basis. I guess that's why the UK CAA include them on the syllabus for the CPL(H), though I agree that it's probably unwise for inexperienced or non-current PPLs to go out and attempt them in anything other than a light wind with plenty of room to spare.
I guess you've led a very sheltered life;)

Before MM and PPF#1 get their handbags out let us return to the topic; which I believe is should a low time pilot make a downwind approach.

I like PPF#1 have flown many hours (not going to tell in case MM says he has more than me:rolleyes: ) in many roles, ranging from basic Stage 1 drills with the Army to SAR display pilot and now bus driving in the N Sea. Also like PPF#1 I have made very few downwind approaches as I have always strived to make the final approach into wind.

I know of many cases where a downwind approach appeared the favoured choice but on reflection it would have ended in, at the best an over torque and worst a bent a/c. Examples of this are an approach into a bowl with the wind blowing into the bowl. The approach to one of the radar sites in the Falklands (Alice? memory going!!) where the HLS was below the ridge line and the curl over turned the 45kt headwind at +500ft into a 30kt tailwind on short finals.

The morale of this is that if possible make your final approach into wind. There will be time when this is not possible but if you are a low time pilot who is not practised and very comfortable with downwind approaches then land somewhere else.:D

HF

Catch 'em early and train them well...this is a helo they are flying, not a flaming 747. Use the a/c for what it was designed, but with common sense and within its individual capabilities.

This industry isn't quite a nanny state :ouch:

Quite.




The system said I couldn't use just one word so I have to fill out the message with this stuff

Phil

PPF#!

As I said before, it would appear that despite your enormously impressive CV, your peers just do not agree with you.

I think TC has said all that needs to be said about the downwind approach.

tail wind approaches on helicopter
 

dear all
I have a genuine query. please advise if there's anything wrong in carrying out a downwind approach on RW at sea level free from all around obstructions; tail wind component of not more than 05-10 knots; ROD not exceeding 300-400 fpm on a seaking, culminating in a running landing.
Keeping in mind principles of LTE and ETL, my personal experience has been to compensate 5-10 knots of tail wind with reduction of IAS while keeping the ground speed constant. This obviates the requirement of excessive nose up attitude prior to touch down in order limit the landing speed(undercarriage considerations).
comments pse
navy pilot

tail wind approaches on helicopter
 

Where is the question?
What you describe can be found in every second AOP. So what should be wrong with it?

Just be a bit cautious with vortex ring, I think.

If you're flying a similar approach angle and closure rates as you would into wind, there will come a point where you drop through zero airspeed but still have a fair rate of descent on, possibly setting you up for vortex ring state.

Having said that, I suppose if you're using a max of 10 knots tailwind and you do a 10 knot run-on, it would be similar to doing a zero-zero approach on a calm day so it might not be a drama.

If the area is free of all obstructions-why would you want to land downwind?

There is a simple rule regarding helicopter operations:
You can do (almost) ANYTHING-as long as you fully UNDERSTAND what you´re doing there...

Your question cannot be answered, as many factors are missing...
Weather conditions, PA, Weight of the aircraft (fuel on board, pax,cargo), dimensions and structure of the landing area and the surroundings and much more...