Cross wind approach [Archive]

jellycopter

1st Jan 2005, 13:16

Raven2

There's no problem with what you describe for private operations. You just need to be aware that you'll be putting yourself in the avoid area of the Heigh/Velocity chart. Furthermore, with a 90 x-wind, as you descend on the aproach, you'll notice that your IAS will show less than your real airspeed due to the apparent wind being off to the side.

This means two things;
1) if you tend to fly your approaches on the ASI you'll need to fly it faster to maintain the same 'indicated' airspeed which is not clever.
2) if you fly your approach visually using the apparent groundspeed (and I'd suggest an apparent gentle walking pace for such an approach), as you check your IAS on the approach you'll notice it reads zero very early on the approach which can shock the inexperienced/unwary into unnecessary overshoot action.

Therefore, my recommendation would be to set up your approach accurately from quite a long way out from known parameters; say 500ft agl and 50kts ( or 300ft agl and 30 kts). As you reach your descent point, forget the IAS but concentrate on maintaining the apparent groundspeed. Scan the VSI at regular intervals and be ready to overshoot if it starts to look like needing to exceed 500fpm to get in. Remember however, a helicopter which has ETL (Effective Translational Lift) cannot get into Vortex Ring so this 500fpm 'rule' isn't entirely necessary until later on the approach.

As regards the vertical descent; no problem. (You should have done this during your PPL(H) training). To judge the correct height, shoot your initial approach to just above the tree tops (10ft) on the near side of the Confined Area. As you reach this point, look ahead to the horizon and high-hover taxi forward until the centre of the CA (or until your tail is clear). From here, establish a high hover and gentle vertical descent to the ground. You can scan markers directly ahead of and to the side of the aircraft to ensure a vertical descent. (You could also yaw into wind before you start your descent to make handling easier).

Before you intend to try such an approach (and departure), get your head into the Flight Manual performance graphs and make sure you've got Hover Out of Ground Effect performance + 5%.

However, having said all of this, if you didn't complete this type of excercise during your training (and from your question, it sounds like you didn't), I'd recommend getting a refresher lesson from a suitably experienced FI before you try it on your own. It'll cost you a bit extra, but it'll be a whole lot cheaper than a main or tail rotor strike!

J

muffin

1st Jan 2005, 13:53

Jellycopter

That was a useful refresher. However, I was under the impression that the HV avoid curve data only applied to take off?

I often go into the back of the carpark of a local pub. This has only one way in and out, as there are buildings on two sides and trees on the third. The only approach and exit path is over open ground which drops away very sharply from the back of the site - in fact the kids were sledging down it when I went in on Xmas Eve (no, I did get them moved first before anybody comments). I only normally go in there in no wind conditions, as you are often faced with either a downwind approach or a downwind departure. Being cautious, I don't really want either as it is a tight little site. However I have often mused about trying it if the wind is across the approach/exit path and the preceding comments are therefore very relevant.

Maybe I will get an experienced LH seat person to ride in with me sometime when the wind is across.

Thomas coupling

1st Jan 2005, 14:15

The "dead man's curve" involves HEIGHT and AIRSPEED. It doesn't matter what you are doing at the time (the helo doesn't care whether you are approaching to land, cruising or taking off).
IF you are at a height and an airspeed that is defined within your curve, and the engine stops, then ....BINGO :{

Provided your flight is private, you are perfectly entitled to fly cross wind to and from a site. I would suggest, however, that to maintain your mantle as a 'professional pilot', you know what to do when things go wrong 'out of wind'......

pleasant flying.........

tagg

1st Jan 2005, 14:31

There can be some confusion with regards to th HV diagram. In the some helicopter handbooks they show the diagram with a recommended take-off profile and not a landing one.

Therefore pilots can be left thinking it only
applies during take off.

raven2

1st Jan 2005, 14:39

Jellycopter,

Exactly what I was looking for!

Thanks

Raven 2 :cool:

Helinut

1st Jan 2005, 16:12

Someone like Shawn may be able to confirm this, but I believe that there could be a difference between approach or departure. During departure (high power and positive collective pitch) the rate of RRPM decay (post engine failure) will be greater than during arrival (lower power and collective pitch). For this reason, you are likely to be be in (somewhat) better shape during arrival than departure at the same height/airspeed combination. You will also be in better shape if the helicopter is light.

S76Heavy

1st Jan 2005, 19:43

AFAIK the H/V diagram is based on Take off power, to allow for the worst case scenario. Rrpm decay will be highest with an armful of collective. Also, it takes a fixed reaction time into account.
Hence, for descends, the dead man's curve will be smaller, but how much smaller has not been fomally established.

Flingwing207

2nd Jan 2005, 02:09

Take a Schweizer 300CB at 20kt airspeed, climbing through 400' at 500'/min. You are using 26"mp or about 160hp to keep the blades spinning. Now take the same 300CB and descend at 20kt, 500'/min. You'll be using about 20"mp, or well under 100hp to keep RRPM in the green.

Now imagine a power loss in each situation. Obviously the RRPM would drop more dramatically in the climb than in the descent. But it would also take longer for an autorotative state to develop from the 500'/min climb, so RRPM would take longer still to recover. Put another way, you'd be fairly comfortable entering a practice auto at 20kt, 400', 20"mp and descending. You'd certainly think twice about chopping the throttle at 400', 26", 20kt and climbing.

That being said, a hovering descent at 200'/min would require substantial power, not much less than a stationary hover, so you should definitely respect the H/V diagram for this type of operation.

Devil 49

2nd Jan 2005, 04:33

A couple more thoughts:
Approach speeds in this case should be predicated on aircraft performance (factor in A/C weights, too), pilot experience, terrain, entry and exit paths- lots of things that would make me loath to say 40, 50, 60, or any fixed rate of knots. Some aircraft are harder to slow down in a descent. Some require speed to keep emergency maneuver capability. Altitude or airspeed, keep as much of both until you can't anymore, and usually you can carry speed longer. Suggestion- try to keep best glide speed (at least) through the transition, down to 2-300 feet absolute altitude (approach initiation point), when you're on angle, to your high hover point for the vertical. 70 kts or so in a 350, 60 in 206, etc. You'll know you had too much speed if your approach descent requires big power reductions to keep on angle, or slips. Do it again, slower.

Don't restrict yourself to conventional airplane patterns. Circling transitions, at least down to the initiation point (2-300 feet AGL) are a good way of keeping the LZ in sight, being neighborly, keeping forced landing sites in range and controlling speed. If you have good LZ location, you can also zig-zag, dog leg, what ever, the transition. Do it over the best escape terrain, within performance limits and flying neighborly.

If you gotta do it crosswind, put the wind on the strong side, i.e. right side for French products, left for the rest of the world (unless you're in a Bell...). Easier to reject the approach.

As the man said, above ETL, you don't have much to sweat regards vortex ring. If your approach involves extreme descents/speeds, however- abort. Your plan is flawed somewhere.

If you have to zero airspeed and continue a descent, slow is the word and high is good to make the transition- until you have more experience as to the dangers and trades to minimise hazards.

Descending into a hole, limited escape options, is not the time to get impatient or careless. 200 fpm vertical descent, is safe, slow enough that location in the hole is manageable. From a 100 feet, it's only 30 seconds at that rate. Don't rush it.

This is all a process trading helo flexibility against risk. Survival first!

[email protected]

2nd Jan 2005, 06:28

Raven- you don't say what height you need to maintain to clear the obstacles but you could try a shallow or level approach to a high hover and then a vertical descent. As your speed reduces in the latter stages of the approach, use a combination of pedal and cyclic to gradually yaw the aircraft onto an into wind heading whilst still maintaining the approach track - ie you end up sliding sideways into the into wind hover above your landing site. We use this technique a lot in the mountains where you must avoid the lee of ridges, pinnacles etc due to turbulence.

paco

2nd Jan 2005, 14:55

I can confirm that the H/V curve is not valid for approaches, although you would be well advised to take note of it.

Phil

The Rotordog

2nd Jan 2005, 21:40

Paco:I can confirm that the H/V curve is not valid for approaches, although you would be well advised to take note of it.This is the kind of bullsh*t thing I hate to see on this board. "I can confirm..." Oh yeah? Who are you, dickweed? Did you write the AFM for every helicopter on the market? You can confirm, can you?

I give pilots a lot of credit...normally. But this kind of crap just frosts my cojones. It's like Shawn saying it. He's an authority, right? I mean, he's Mr. Big-Time Test-Pilot! If enough people say junk like that, some un- or poorly-trained pilot will stick it in the back of his mind. "Well, the H-V chart only applies on take-off. I know that because Paco and Shawn and S76Heavy told me so on PPRuNe!"

Me, I would go by what the manufacturer of my machine tells me. If they do not specify otherwise, I would conclude that the H-V chart applies everywhere, especially for pilots who's skill level falls short of a Shawn Coyle or, evidently, Paco (meaning guys like me). Intellectually I would know that light/low-power/descending is better than heavy/high-power/ascending, but I would not summarily disregard the chart merely because I was "landing" and assumed that I was therefore granted some sort of immunity. If you are deep in the shaded area at very low airspeed with a minimal descent rate and high power, the helicopter won't know if you are landing or not.

So guys, stop talking out of your asses and try being just a little professional (I know it's tough for some of you). In-the-shaded-area is in-the-shaded-area. We fly in it sometimes, yes. But we do not disregard it. Only a true fool would.

Rant: OFF

S76Heavy

2nd Jan 2005, 21:56

A bit touchy, aren´t we? Feel better now?

I suppose that Darwins theory applies to flying, the stupid and downright silly will get themselves killed (as will sometimes the skilled but unlucky), the rest wil learn and live..for now.

No comment on this board, in the crewroom or elsewhere absolves any pilot from reading the manuals and understanding what the limits of his aircraft and as importantly, his personal limits are. Anybody dumb enough to ignore that will get himself into trouble.
That therefore does not mean that we should no longer discuss theories on this forum because it might not be so blatantly obvious to someone that to take anything as gospel might get him killed. But if it does, he has himself to blame. Because this is a forum for professional pilots and it is not meant to cater for the lowest denominator. The day it dumbs down and does, it will be a sad and empty place.

The Rotordog

2nd Jan 2005, 22:59

S76Heavy:No comment on this board, in the crewroom or elsewhere absolves any pilot from reading the manuals and understanding what the limits of his aircraft and as importantly, his personal limits are. Anybody dumb enough to ignore that will get himself into trouble.
That therefore does not mean that we should no longer discuss theories on this forum because it might not be so blatantly obvious to someone that to take anything as gospel might get him killed. But if it does, he has himself to blame. Because this is a forum for professional pilots and it is not meant to cater for the lowest denominator. The day it dumbs down and does, it will be a sad and empty place.I have seen an attitude on this very board in which some people feel that *any* technique that involves a level of skill more advanced than that of a private pilot should not be discussed for fear that some low-time Robbie pilot will go out, try it and kill himself. So I am first in line to say that yes, every aspect of helicopter flying should be discussed here. Advocating such things as steep- or crosswind approaches is one thing. It is quite another to say patently absurd things like "The H-V curve does not apply on landing." There is where I have to call foul. If that makes me "touchy," so be it. It is not how I fly.

And I have been flying a long, long, long time in both rotary- and fixed-wing. I cannot say with certainty that I would have made it to this point if I took the attitude that I could just ignore various performance charts at my discretion- especially charts that offer such scant margin for error in the first place! Maybe some pilots can rely on their superior skill for their entire careers. Me, I'm not that good and I don't even pretend that I am.

I also know that while the H-V chart does not reside in the "Limitations" section (with those rare exceptions), it does not mean that I might as well yank it from the manual and toss it out the window. And I really take offense at those who suggest otherwise. Like I said, if that makes me touchy, I can live with that.

Skeeter Pilot

3rd Jan 2005, 01:27

This post has been an interesting read but a little perplexing to see such differences of opinion on a manuvore that ought to be fairly uniform in technique irrespective of aircraft (rotory-single engine in particular) type.

However, I have a questions drawn from the above posts.

Devil 49 said:
"If you gotta do it crosswind, put the wind on the strong side, i.e. right side for French products, left for the rest of the world (unless you're in a Bell...). Easier to reject the approach".
I fly an old underpowered machine, so wind speed and direction, fuel load, passenger weight, ambiant temperature, etc. are always carefully considered before a departure and approach. My machine is British built so the rotors turn the "French" way, clockwise when viewed from above. Therefore, with regard to the above comment, I would keep the wind on my left side, not right, so if things didn't go as planned and I found the throttle on the stop with the Rrpm decaying, I would turn 90 degrees left into wind and in doing so would off-load the tail providing additional power to the main rotor. Does this make sense, or have I miss understood something crucial?

jellycopter said:
"1) if you tend to fly your approaches on the ASI you'll need to fly it faster to maintain the same 'indicated' airspeed which is not clever.
2) if you fly your approach visually using the apparent groundspeed (and I'd suggest an apparent gentle walking pace for such an approach), as you check your IAS on the approach you'll notice it reads zero very early on the approach which can shock the inexperienced/unwary into unnecessary overshoot action".
I was always taught when carring out downwind/crosswind approaches to maintain a positive airspeed (anything will do but if you can keep 20kts. that's great) until the point that you pedal the helicopter round into wind and a hover, again, if it is possible to pedal it in the direction that off-loads the tail you benifit in power gain additional to the power gain from lowering the lever to prevent climbing as you come round into wind.

jellycopter

3rd Jan 2005, 08:53

Skeeter,

You make some valuable comments and I too employ similar techniques when flying my very under-powered Rotorway Exec.

Regarding the option of maintaining IAS however, it can cause some confusion to inexperienced pilots who do not consider that the ASI under-reads significantly when the wind is not 'blowing' down the pitot from dead ahead. This gives the helicopter a significantly higher groundspeed than desired for such an approach. This inturn gives our inexperienced pilot a harder task at the bottom than it would if the groundspeed was carefully controlled from the top of drop.

Notwithstanding any of this, my original post was aimed at Raven2 whom I beleive to be less experienced due to the nature of his question. Furthermore, based on his 'name', Raven2, I'd assumed he was flying an R44 Raven 2 and therefore tailored my answer to fit the aircraft type he'd be flying.

Cheers,

J

S76Heavy

3rd Jan 2005, 09:08

To Rotordog:

No problems with your opinion, I just think you could have chosen a more moderate way of expressing it, hence the "touchy" comment.
Discussing the H-V diagram means to me having it clear what entry position the manufactor used to determine the diagram. All helicopters I've flown had it stated that the diagram was based on a T/O power setting with a fixed delayed reaction time.
It's merely about getting the definitions right before the discusion.

To Skeeterpilot:

having the wind on the strong side is to ensure full T/R authority, but since you fly an underpowered machine, every technique is a trade off.

[email protected]

3rd Jan 2005, 11:17

Skeeter - the idea behind flying with a right crosswind on your machine is that you are flying with less power pedal (and therefore less power) than if the wind is from the other side.

We know the fuselage wants to weathercock into wind and pedal is required to hold it out of wind - in your aircraft the right pedal required to combat a left crosswind would mean you would reach your power limit sooner than if you were using left pedal to combat a right crosswind.

I think holding 20 kts IAS on a downwind approach until you pedal it round in the hover is going to be very, very exciting. The whole point of a downwind approach is that you end up with a negative airspeed as you reduce groundspeed towards the hover.

oldbeefer

3rd Jan 2005, 14:49

rotordog. You really should check your facts before commiting yourself to a crap comment. HV curves ARE based on max power at max AUM. Which means that if you are in the descent and at less than MAUM your chances are better than the HV curve would indicate. There is still one, of course, but it shrinks as amount of collective applied and mass reduces. So, it is worst case. Why else do we (or some of us) teach approaches which would appear to put us in the avoid curve?

Thomas coupling

3rd Jan 2005, 17:35

I have to agree with rotordogs comments (maybe not his attitude:eek: ).
IF you are inside the H/V curve (iaw your FLM) then you are going to CRASH the helo if your power plant(s) stop working.
This means that the average pilot will bend his/her helo and maybe more. It means just that:

You will NOT have time to recover the situation (to a controlled autorotation) before striking the ground. You might crash more gently if you are into wind or taking off or cruising or doing the samba! but you WILL CRASH:uhoh:
That is the definition of the H/V curve:

"In the event a power plant fails in a single engine helo, the average pilot with average reactions will not have sufficient height to recover the a/c to a safe autorotational profile."

If you start 'pursuading' newbies that there are some sexy little tricks of the trade to avoid any pain and suffering whilst INSIDE the dead man's curve.....they will end up, just that:ouch:

Oldbeefer: I agree: the curve is tested at high AUM. Don't think it's tested at max power though???

http://www.copters.com/pilot/hvcurve.html

muffin

3rd Jan 2005, 20:00

As a relative newbie, I think Jellycopter's comment re the accuracy of the ASI when the wind is off the centre line of the pitot is very relevant. Although we are all taught about compass errors etc, the pitot error is never gone into in any depth. Consequently I for one sort of automatically assume that the ASI is always correct and fly by it, although if I stop to think about it that is obviously not the case. As Jellycopter said, it could lead to some interesting arrivals at the bottom of a crosswind descent.

Skeeter Pilot

3rd Jan 2005, 20:26

jellycopter
Thanks for your reply. My instructor taught me to maintain an indicated airspeed to help lessen the chance of entering vortex ring, which at 1000' is not the end of the world but at the end of an approach could possibly ruin the day. I suppose so long as I am happy with the exciting bit at the end it's ok. I can't ask him for his comments as sadly he is no longer with us and there are no current instructors on type. It's an ex. Army machine so apart from my friend (not ex. mil.) who is the only other person current on type, all the people that flew the type for a living have not been current for about 35 to 40 years.

[email protected]
We know the fuselage wants to weathercock into wind and pedal is required to hold it out of wind - in your aircraft the right pedal required to combat a left crosswind would mean you would reach your power limit sooner than if you were using left pedal to combat a right crosswind.
I see exactly what you mean. I suppose it's a "what's best for what type" thing. My machine has no verticle stabaliser (as a matter of fact it has no horizontal either) so the want to weathercock is less. It also has a large diameter tail rotor (6 feet) for a small machine so when you off load it right at the very end when you need it you get a very comforting surge of power. Possibly these two things combined make it the best idea to keep the wind on the left.

many thanks.

jellycopter

3rd Jan 2005, 22:22

Skeeter,

There's a very good Army QHI at Shawbury (if he's still there....I left a couple of years ago now) who used to display the Skeeter for the Army Air Corps. I'm certain he's the kind of guy who would relish getting his hands on one again and would probably be glad to offer some advice and top-tips in return. If you're interested, I'll try and put you both in touch. If it works out, maybe you'd let me get my hands on it aswell;)

J

GLSNightPilot

3rd Jan 2005, 22:29

Skeeter, with an underpowered machine, I think it's even more important to keep the wind on the correct side. There is some weathervaning tendency with any helicopter, and counteracting that requires power from the tail rotor, which subtracts power from the main rotor. With the wind on your left side, you need more right pedal to keep the nose straight, thus you're using more power, and come closer to reaching torque or engine limits, or even having an exceedance of some sort. It's not always possible to keep the wind on the correct side, but given a choice, I always do it.

Skeeter Pilot

4th Jan 2005, 22:11

GLSNightPilot

Thanks for that. I'll try various approaches in the open and monitor the differences.

jellycopter
I think I may have met him back in about 1996 at Weston Heli Days. It would be nice to make contact, could you let me have his no. via a PM?

Kind Rgds.

the coyote

5th Jan 2005, 08:02

Interesting reading, but a few things come to mind:

1 - It seems everyone seems hugely concerned about the H/V curve, and the shaded 'avoid' area. (where ag, mustering and sling pilots live just about all day long...)

In my opinion, for this type of approach you simply have to accept that you will be inside the H/V curve for a fair period of time. The chances of the engine failing during this period are FAR less than the pilot flying a bad approach and winding up in VRS or running out of power at the bottom and hitting hard. Prioritise your risk: Why fly an approach profile to try and stay out of the H/V curve (and minimise an already minimal risk) while doing so MAY greatly increase the far more significant possibility of VRS or having insufficient power available? Be aware of the H/V curve and don't fly in it if you don't have to, but don't be hung up on it.

2 - Second big school of thought is unloading the tail rotor by having the crosswind on the appropriate side.

While I don't disagree with the concept, you shouldn't be flying this approach under the given conditions if you don't have sufficient power available, regardless of where the crosswind is from. So why be concerned about unloading your tail rotor and in doing so select an approach path that may in fact be less suitable due to obstacles, angle, head wind component or forced landing areas? (As an aside: Say you have the wind from the left to help reduce TR demand (non French). IF the engine does happen to let go, its going to yaw left and into the wind. While this might seem great, you are going to end up completely crossed up to the original approach path, in auto sideways with a new view, close to the ground and trying to work a new plan with no time and little speed. Try it (with an instructor): set up high with very little forward speed, lots of power and a brisk left crosswind and chop the throttle. It will give you an idea of how pear shaped you can get.)

3 - No one has talked about doing an in flight power check to assure you have power available to do this approach at the time.

Yes, check the performance graphs. But what if the ambient conditions are different, or you've got an extra person on board etc? I strongly suggest to do your homework and develop an in flight procedure that will fairly accurately tell you what your HIGE and HOGE power required will be under the conditions. Make sure you've got what you need to do the job.

I personally don't like the idea of an approach to a point and then descend vertically, unless the area is so confined that you have no other choice. Aside from the increased risk of obstacle strikes, it will demand more power than flying a constant, albeit steep, angle all the way to the ground. No problem IF you have HOGE power available.

It takes less power to descend than it does to hold height for a given speed, and if you hold your angle to a ground effect hover you will always fly the approach with less power.

As a general rule with all other factors equal, I would take the best line in that gave me the shallowest angle within the confines of acceptable wind and fly a constant angle approach all the way to the hover.

An approach angle is a combination of ROD (towards the ground) and forward speed (over the ground). So if you have to do it crosswind or downwind, then make sure you hold your angle, keep it slow by reference to ground speed and your ROD won't be a problem.

All this ASI talk, how then do you make an approach if your ASI has failed?

That's gotta be the longest ramble I've done, hope it makes sense!

The Rotordog

5th Jan 2005, 17:04

Coyote- excellent post! You describe exactly how the professional pilot "approaches" such a situation (no pun intended). And you're right, it's all about priorities- don't focus or obsess on one thing to the exclusion (or detriment) of others. And I agree with you totally about the H-V curve. What I disagree with is pilots who convey the attitude that the chart may be disregarded merely because they are landing, or that it does not apply to the landing mode. To me, those are dangerous mindsets.

My experience has shown me that some low-time pilots really don't know how to make a true confined-area approach. Oh, they know the theories, and can do a passable steep approach to an airport. But ask them to go out and actually put the bird into a small site with obstacles around, maybe not great forced-landing areas on the way in *and* a crosswind to boot and...well...sometimes their improvisational skills leave something to be desired. Why? Simple lack of experience. Or maybe they get in a hurry and don't take enough time to think things through. We who do it for a living get ourselves into such situations as a matter of course, and we get proficient at them because we have to.

Like you, I would advise against an "EMS-type" of approach in which the pilot comes to a high hover with a subsequent vertical descent. If the site is *that* tight, I'd think very seriously about whether I need to be going in there (somebody would have to be bleeding). To my thinking, a constant-angle approach (even if the course over the ground varies) is much better and safer...more stable and controllable. Plus, you don't have to mess with the HOGE capabilites of your ship.

Helicopters can make very safe, very steep, very controllable approaches. They do not have to be autorotative if you keep the RoD and airspeed in check. Keep it above ETL in most helicopters and you'll be fine. The beauty of- and the problem with- flying helicopters is that when you operate off-airport there are no hard-and-fast rules. You have to make it up as you go along based on many factors (the aforementioned site size, obstacles, forced-landing areas, noise-sensitive areas, wind, load, OAT, how you're feeling that day...). You use your cumulative amassed knowledge and experience and do the best you can.

Ivor E Tower

5th Jan 2005, 18:37

Rotordog
My experience has shown me that some low-time pilots really don't know how to make a true confined-area approach. Oh, they know the theories, and can do a passable steep approach to an airport. But ask them to go out and actually put the bird into a small site with obstacles around, maybe not great forced-landing areas on the way in *and* a crosswind to boot and...well...sometimes their improvisational skills leave something to be desired.

I couldn`t agree more Rotordog. However in the UK the CAA in their wisdom won`t allow you to conduct any "off airfield" training during your PPL. Students never therefore get to fly proper confined area ops during their course (unless the airfield has one).

Most of the time it has to be simulated by the instructor (ie:imagine a big tree
in front of the landing site). Which to me doesn`t make sense, as when they get their shiny new PPL they can go off and land in their back garden(size and location permitting)

muffin

5th Jan 2005, 19:01

That's very true. So what you have to do post PPL is to teach yourself slowly. The problem is made worse by the fact that many self fly hire operators will reputedly not allow hirers to land off airfields, so they never get the chance to learn and practice. Of course, if you can afford it you just buy a helicopter yourself and do whatever you want. My "confined area" during PPL training was the top surface" of an old WW2 pillbox. Not very confined perhaps, but it didn't half concentrate the mind to have to land on the thing.

Ivor E Tower

5th Jan 2005, 19:06

Muffin, it didn`t take you long to get the hang of the pillbox approach, if I remember correctly.

407 too

5th Jan 2005, 19:32

unless i've mis-read the replys to your post, there is one thing nobody else has mentioned yet. You mention trees as one of the limiting factors, how dense of trees, if they are dense enough to block the wind you will loose any advantge the wind gave you (you are still in effect flying even at zero ground speed) as you descend below the canopy.

you will now need a larger amount of power to compensate for the no-wind descent

this power requirement is immediate if you are to stay out of trouble and maintain your descent rate

too close to the trees can also give you a down-draft

my only advise is have your power fully developed early during the descent (if too much, it's easy to let some off) check what you have left, if you feel you would not be able to stop a no wind descent, fly away, if you have enough power left, and the approach feel stable and good, be ready when you descent below the canopy.

(of course if the canopy or trees are NOT dense enough to block all wind, save all the wind i've used here for a time when there is a wall of trees) :E

the coyote

6th Jan 2005, 04:17

I am absolutely astounded that you can get a licence in the UK that entitles you to land in a confined area, without ever having gone into one in a training environment.

Isn't that one of the big reasons we fly these things, to enable us to go into places where fixed wing can't?

What about if you train for a CPL? Does the CAA allow you to do the "Real McCoy" then?

By the way, when I used to do ab-initio training, you would obviously get the student to first fly the required steep approach and vertical take off profiles at the airport until they had them down pat. Then do exactly the same thing in amongst the trees and they would ALWAYS make a pizza of it in the beginning. I used to tell them that the aircraft didn't know that the obstacles were there, and there was no difference from the aircraft's point of view to what we'd just done at the airport, but it goes to show just how much the nerves and a new environment can interfere with basic handling and decision making.

Ivor E Tower

6th Jan 2005, 09:05

Coyote

What I should have mentioned is the PPL training has to be carried out at a Licensed site. There are a few sites other than airfields in the UK that are licensed for training but not many. Even then they are only usually allowed to do certain excercises at the site.

So basically you are limited to airfields. Doesn`t make sense does it.

organ donor

6th Jan 2005, 14:16

PPL training does not have to be carried out AT a licenced airfield, it has to be carried out FROM a licenced airfield. There is nothing to stop confined area training from taking place off airfield so long as you do not physically touch down, and you are obeying the rule5 etc.
Confined area is in the syllabus and must be taught realistically, not with pretend trees to fly over. You can't let a fresh PPL go off flying into his back garden when he/she has never performed a confined area landing.

[email protected]

6th Jan 2005, 15:29

Coyote - your paragraph about engine failure crosswind was incorrect - in a Gazelle or similar rotation aircraft the nose will yaw right as the engine fails ie in the same direction as the power pedal which is opposing a torque reaction that has just been turned off.

You and rotordog might not like the approach to high hover and vertical descent but it is often the only way to get into a proper confined area ie a small one. One problem with a steep approach to the forward edge of the LS is that of judging tail clearance - at least if you recce for a vertical descent you can pick suitable markers to help you. The other advantage of the 'EMS' if that is what you want to call it approach is that it is much quicker to make a fast, level approach to a hover and then descend vertically than it is to make a slow, steep approach all the way in (and you spend more time in the HV curve).

407 you are quite right about losing wind effect behind the trees which is why you shouldn't do confined area ops with limited power - HOGE plus a 10% thrust margin is recommended by Brit Mil operators for exactly this reason.

Organ donor - do any training establishments in UK have proper confined areas eg clearings in trees that they are allowed to use - in theory to land off airfield you need landowners permission and must notify the police; I suspect that is why much CA training is conducted half heartedly on airfields.

the coyote

6th Jan 2005, 15:45

Crab,

Not incorrect at all. You will notice I was using "non French" in the example, ie counterclockwise when viewed from above.

If left crosswind is required to reduce TR demand, then left yaw will occur upon engine failure.

In a Gazelle etc you will need a right crosswind to reduce TR demand and yes, right yaw upon power failure of course.

Good point about the 'EMS' approach being quicker, and in a dedicated EMS situation you also have the advantage of a crewman keeping an eye out. But it will still require more power in my opinion, which is no problemo if you've got it. And its a pretty small area if you MUST descend vertically.

I get the feeling from the original question that Raven2 is not in a time critical situation where they would benefit from doing such an approach, and I doubt whether they have a couple of thousand horsepower up their sleeve either.

But hey, everyone's opinion is as valid as everyone else's! :ok:

Hughes500

6th Jan 2005, 16:39

Probably my biggest concern is inexperience in confined area. I have often been less than impessed as an examiner when examining PPL's.

After all what is the ppl going to do with his brand new licence yup take it home. Realistically CA is done at my place starting with small fields ending up in clearings in the woods. You only need land owners permission if you touch down. Providing you are 500 ft away from person, structures vessels etc - no problem ! Also I think one may be infringing the law if one landed - definition thing of stsrting and ending from a licenced field !

Instructors out there please teach your PPL's proper confined areas - thats what the damed thing was designed to do !!!!!

Ivor E Tower

6th Jan 2005, 16:48

organ donor

I used to train from Cranfield where we had approval to conduct confined area at a site away from the airfield. (area Alpha if anybody remembers) From what I have heard now the approval had been taken away as it was not licensed. (the caa took the approval away).

I may be wrong and stand to be corrected.

organ donor

6th Jan 2005, 19:41

There's no problem with teaching confined area "landings" off airfield - so long as you don't touch down, and you follow all the relevant rules, you are'nt doing anything wrong.

Crab : There is no requirement to inform the police when landing at a confined site, landowners permission is needed if touching down, but thats not allowed when training.

I would be more concerned about not teaching the student correctly.

jellycopter

6th Jan 2005, 22:50

Crab, you state:
HOGE plus a 10% thrust margin is recommended by Brit Mil operators
From memory, don't the Brit mil use OGE+5% as I quoted in my initial post? I thought we used to use HIGE + 10% as a rule of thumb for calculating whether we had the required performance.

Just the CFS pedant in me working its way back to the surface!:ugh:

J

MightyGem

7th Jan 2005, 00:55

There's no problem with teaching confined area "landings" off airfield - so long as you don't touch down,
Ah, but if you don't touch down, then you are going below 500' with no intention of landing.

Crab, I think the informing the police is just a military thing. I got picked up for mentioning it here a while ago.

muffin

7th Jan 2005, 07:04

Yes, this was what a plank driver was prosecuted for a couple of years ago. It is OK to make a landing at a private site with the owners permission, but you have to actually land. Go arounds and situations where you don't touch down are a breach of rule 5.

I think?

jellycopter

7th Jan 2005, 07:52

There's absolutely nothing wrong with flying below 500ft (yet!) provided you stay at least 500ft (in any direction) from 'persons, vehicles, vessels or structures'. The ground isn't mentioned in this particular sub-para of Rule 5. Where it gets sticky is if you are practicing CAs for example, and you attract an audience within 500ft of the aircraft. Provided you land the heli you're OK. If you have no intention of landing, you're not.

Another interesting point is the Recce of the CA. My personal take on this, is that you must carry out your recce within the restrictions of Rule 5 but when you commence your approach, you can ignore the '500 ft Rule'. So slow approaches are good as they are useful as a low recce.

J

[email protected]

7th Jan 2005, 11:55

Coyote - quite right I should have read your post more diligently.

So if I understand the confined area dilemma correctly for civvy ops - you can break the 500 foot rule providing you land in the CA but you are not allowed to land away from a licenced aerodrome for PPL training purposes, only hover. No wonder no-one does CA trg in UK.

Jelly the HIGE + 10% was from the Gazelle days and it was 10% Tq in hand from your hover figure not a 5% or 10% thrust margin. Normal ops require a 5% TM but our mountain flying and winching needs 10%. IIRC the AAC use 10%TM for CAs.

organ donor

7th Jan 2005, 11:59

I agree with you that you can't break rule5 while dong a recce. The rule says you are absolved from the 500ft rule whilst taking off and landing in accordance with normal aviation practices. The way I understand it is you must be on final approach or climbout to be absolved.

[email protected]

7th Jan 2005, 14:32

OD, this is what I am trying to clarify - if you make an approach and land you are absolved from rule 5 but if you make an approach to the hover and then depart again, you have neither landed nor taken off and seem therefore to be in breach of rule 5.
If you want to land you must have the landowners permission but unless that land is a licensed airfield you cannot use it for pilot training. Confused? I am!

jellycopter

7th Jan 2005, 15:37

OD,

You are only absolved from the '500 ft Rule' sub-para of Rule 5 when taking-off and landing, but NOT anything else. The '1500ft Rule' for example still applies.

Regarding training for PPL(H) it is my belief (and I stand to be corrected) that you can practice full CA techniques provided you neither land nor infringe any element of Rule 5 and will, by the letter of the law, be perfectly legal. Basically, you need a remote CA without anything to cause a '500ft Rule' infringement.

Daft innit!

J

organ donor

7th Jan 2005, 20:05

Crab :
You are only in breach of rule 5 if you are closer than 500 ft to any person, vehicle vessel or structure and not landing.
If you don't land and stay in the hover, but are still 500ft away from the above you are not breaching the rule, and you don't need landowners permission as you haven't touched down. Remember the 500ft rule does not apply to the ground, only structures on it.
If you land then you are absolved from rule 5 (500ft only, not 1500ft), but you can't land anywhere apart from a licenced airfield while training.

Jelly : You're spot on.

[email protected]

8th Jan 2005, 12:07

So then - other than in the middle of a large forest (which is a crap place to be flying a single engine helo) where are you going to find a realistic confined area that is outside a 500' radius of any person, vehicle, vessel or structure (presumably they include telegraph poles, pylons and fences in the definition of structures)? It would seem to answer the question of why confined area training is given lip-service in the UK.

Skeeter Pilot

14th Jan 2005, 22:35

helicopter-redeye

15th Jan 2005, 16:53

So then - other than in the middle of a large forest (which is a crap place to be flying a single engine helo) where are you going to find a realistic confined area that is outside a 500' radius of any person, vehicle, vessel or structure

Within this sceptred and unpopulated isle, there are a remarkably large number of such locations away from major towns and villages.

Just takes a bit of local recce.

:rolleyes:

[email protected]

16th Jan 2005, 06:51

But you can't use them for pilot training because they are not on a licensed airfield. I know hundreds of confined areas but none which meet the training criteria for CAA.

Hughes500

16th Jan 2005, 08:24

There are enough places in UK to do this even if you are in the SE.
The law allows you to teach CA off an airfield, you have to start and finish at a licenced field. So as long as you do not break the 500 ft rule there is no problem. Interesting though the definition of a struture - one for FL. I have always assumed this to be a building, mast road but not a fence. I will continue to assume this until the enforcement boys say otherwise. What will be interesting is when we join Europe in being 500ft agl - how do you do PFL's and CA ?

Talk Turn

17th Jan 2005, 12:51

Hughes 500

Recover before reaching 500' agl I guess.
If that rule did come in it would kind of defeat the whole idea of a helicopter i.e. fly lower and slower when confronted with less clement weather.

People might bump in to clouds instead of descending and slowing to eventually land.

To continue with the power required posts.

To find out what you need for IGE OGE etc try

^zero wind is better
^On the ground rotors running lever fully down
^Altimeter set to QFE - 0'
^lift to low hover - note altimeter lower now -40 to -60'
^climb until altimeter says just over 0' and you are on the edge of GE (maybe 1'' in a Robinson or 7% in a Jetranger)
^Then climb again to hover OGE (prob. now 2'' or 14%)
HV!

Regarding IAS, pitot, power etc
Maybe, always try to fly in to the relative wind and therfore IAS will read correctly, more stable, better for power, caution tail etc

vorticey

17th Jan 2005, 12:53

i would just do a normal aproach to the top of the trees if i cant make the approach between them. wind wont mater as i have to not be heavy to hover out of ground effect anyway. i make the approach to ground speed not wind speed, all i remember in any wind direction is not faster than 300 fpm decent when you slow below 30knots (the air speed indicator is always acurate if the wool tufts are strait up. once in the hover a bit of wind from the side will cause the rotor wash to interfear with the tail rotor and it gets twitchy also from the left it will go in and out of vortex ring state which makes it realy twitchy and while i dance on the pedals the govenor adjusts rpm witch makes it harder again but i just keep ontop of it and feel the satisfaction of my efforts when i hold it steady as i can.
id also take off between the trees if i could but if i couldnt, just pick it up to the tops and translate from there. hovering over trees uses less power too................................:ok: