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Downwind approaches

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Downwind approaches

Old 8th May 2002, 10:24
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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
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Old 8th May 2002, 10:39
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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.
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Old 8th May 2002, 11:36
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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
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Old 8th May 2002, 16:06
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If you must, but be prepared to throw it away a lot earlier

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Old 8th May 2002, 16:38
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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).
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Old 8th May 2002, 23:43
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Cool

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.
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Old 9th May 2002, 03:27
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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.
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Old 9th May 2002, 07:49
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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
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Old 26th Sep 2003, 01:58
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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
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Old 26th Sep 2003, 02:48
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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 :-
500í 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
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Old 26th Sep 2003, 04:00
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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.

When Downwind is the Only Way


From our first flights in a helicopter, it is drilled into our heads that we should approach helipads into wind. So what do you do, when the only way into a pad is downwind? Anyone who has a little experience knows there are times when approaching and even landing downwind is the only safe option. A very experienced pilot demonstrated the following when I was still very new to Bell medium helicopters, and Iíve used it ever since.

Start off with a fairly normal approach, following the safest path in. Itís important to keep your airspeed and your rate of descent under control while doing this approach. As you get closer to the ground, and to your spot, slow your rate of descent and airspeed. At approximately 50-100 ft back, and 20-30 ft above ground level (AGL) as you slow the helicopter below translation, ensure that you have stopped all downward movement of the aircraft. This will help prevent you from entering vortex ring state. You should now be at a walking pace and less than a rotor diameter from your spot. Watch the ground, as you want to see when your downwash passes you. Once the downwash has passed, you can then resume your descent and land at your spot.

Just remember, that when landing downwind, that there are many points to remember and things to watch for:

You must be certain that you have Hover Out of Ground Effect (HOGE) power.

Make sure you minimize your rate of descent as your airspeed decreases.

You may run out of aft cyclic with a forward center of gravity (CG) and as you reach the helicopterís cross/tailwind limits

Pay careful attention to aircraft limitations.

The tail will be lower to the ground, so be careful of any stumps, bushes, etc.

Be aware that the aircraft will want to weathercock, and will not be as stable in yaw

As a result pilot workload will be higher when performing a downwind landing.

Landing downwind can be safely done, as long as you have planned it out in advance.
Cheers
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Old 26th Sep 2003, 04:39
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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,
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Old 26th Sep 2003, 05:02
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Thumbs up Thanks Randy-g

Thanks for posting that. That little tid-bit may prevent me from balling one up in the future. Good stuff!
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Old 26th Sep 2003, 06:19
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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?
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Old 26th Sep 2003, 06:35
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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. 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?
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Old 26th Sep 2003, 23:59
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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!

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Old 27th Sep 2003, 00:49
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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

Last edited by Randy_g; 27th Sep 2003 at 01:00.
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Old 27th Sep 2003, 05:00
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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
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Old 27th Sep 2003, 19:15
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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 ?

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Old 27th Sep 2003, 21:50
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Head Bolt asked:
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 ?
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.
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