Moggy’s Tunaboat Helicopter Manual Ch.3-A “Different techniques for landing “
Posted on July 17, 2009
PART 3 “Moggy’s Tuna Manual ” “Handling your helicopter “
Chapter 3-A Different techniques for landing
(Been there, done that;
been there, done that;
oh, yawn….! Boring, boring….
In slowly putting together this manual, I have spent some long hours up on the helideck, armed with binoculars, watching the helicopter ‘goings on’ on nearby ships. Ninety nine point nine per cent of the many hundreds and hundreds of landings I’ve seen were routine, professional, smooth, nice looking jobs, often in really adverse conditions, that had all the hallmarks of a ‘good tunahead’.
That point one per cent….
I’ve had my heart in my mouth, and to this day it’s probably still got the teeth imprints on it to prove it!
Boy! I’ve seen one full-blooded crash. And, many times, I’ve seen ’em bounce crazily, yawing sickeningly left-right-left, somehow right themselves, and stumble into a go-around for another attempt at crashing! By the time the pilot admits to you afterward that he got the cyclic shoved hard and painfully into his stomach… that’s a hard landing. I’ve seen downwind approaches, where the guy looks like he’s lost translational lift, lost rotor RPM (Nr), dipped below the edge of the helideck on short finals, hauled around away from the deck… Looking at it from a few hundred yards away on the other side, you just see parts of the disc, the mechanic or deck helper leaping to his feet and running, and then, mercifully, a few seconds later, one little Bell struggling back into the sky!
It’s left me shaking, watching across from another boat, and I don’t know about the mechanic with a close up view! I have heard some good mechanic’s stories afterward though…
Oddly enough, you will hear some guys telling you that helicopters rarely crash on landings on tuna boats.
I don’t know where these guys get their information, but this statement is not correct. It is true that they mostly get away with it, in the sense that they walk (or stagger) away from it! They tear great gouges in the helideck, knock out aerials and radar domes (John Walker told me his gang were averaging one -expensive- Immarsat dome a year), and re-adjust their helicopters in ways not pleasing to the helicopter owner! Astonishingly few get killed during the landing however, despite trying hard sometimes.
So it is fruitful to look hard at the techniques associated with landing our beast on this pitching, rolling, heaving deck, with spray lashing about, and nasty, hungry waves seemingly waiting eagerly for you as you approach nervously on your first few rough weather tuna boat landings!
I’ve written this particularly with low time pilots in mind. The 200 to 500 hour fresh Robbie graduate with his brand spanking new Commercial License. And with the intention of getting you to think things through for yourself. I will list five different approach techniques, all of which I have seen out there, and ask you to read up on each of them. Then I will ask you to mull it over, arrive at your own conclusions, and take a break. Have a cup of tea. Then come back, with some definite ideas of your own about how you feel about each of these five approaches I have described. THEN read my opinion on each of these approach techniques…
And feel free to entirely disagree with me. My intention is to get YOU thinking about the issues. Not to portray myself as some wise old guru who knows everything, because, believe me, I don’t….
First, we’ll talk about a day with a calm sea. No real swell, no real pitch, roll or heave to think about. A nice day to be a tuna pilot! (and a tuna mechanic, if you’re carefully watching your brand new pilot).
To make the conversation easier, I will loosely categorize approaches this way:
1. Low approach
2. Super low approach
3. more or less level (with the helideck) approach;
maybe a slight, slow descent going on
4. high approach
5. ‘very high’ (steep) approach
1. A ‘low approach’ is an approach just under the level of the helideck, maybe 15 to 25 feet above the water, requiring a small but definite ‘lift’ of a few feet towards the end to get up onto the helideck. You will see a lot of those.
2. A ‘super low approach’ is just what it says. Almost a high hover taxi towards the ship,maybe 6 to 12 feet above the water.
3. A ‘more or less level approach’ comes in at or slightly above the height of the helideck. No climb is necessary, and if anything a slight descent is taking place along the approach path. If the helideck is at, say, 25 feet, then this approach might start out at, say, 40 feet above the water, and very, very slowly come down to the helideck. The approach angle is very, very shallow however. You will see a lot of these.
4. A ‘high approach’ has a definite, constant, stabilized approach angle. It might start out at 200 feet, 300 feet or more, and reduces smoothly, constant rate of descent, no more than 300 to 500 feet per minute.
5. A ‘vertical approach’. You arrive exactly over the helideck at, say 200 to 300 foot, and do a steady vertical descent.
So, young sailor, what do you think? For now, why don’t you STOP reading right at the end of this paragraph, think about these five methods, and see what you think of each. It really is well worth having a break, making yourself a cuppa tea, and see if you can guess what I think of each method. Remember, opinions vary, many people may well disagree with me, and this is where you are encouraged to start thinking these scenarios through beforehand, from the comfort of your favorite easy chair, BEFORE you go flying off a REAL tuna boat, with maybe 200hours helicopter time, and learning-as-you-go about things you have never even thought about, because nobody has bothered to tell you about them….
Welcome back, my friend.
Well, here’s another question for you: What different factors can you list that should come into your consideration?
Avoid area, you say? Good.
Direction of the wind? Yes, absolutely.
Strength of the wind? Yes.
Size and shape of the helideck? Yes….
If you got all those, you’re doing good. But there are more….!
Remember, now you are faced with something you never experienced in your basic Robinson helicopter in your primary training. We will return to this. But first, let’s say something about those five different ways of making the approach.
All of which I have seen, for real, many times. Let me give you some ‘food for thought’ and the chance to chew things over again. Remember, form your own opinion. This is not ‘the gospel according to Moggy’….
(Remember also, right now, for the moment, it’s a reasonable day, with no significant pitch, roll, or heave to talk into consideration.)
1. low approach
Brrr!!! I don’t like it at all! Talk about living in the avoid area! Remember that sudden ‘partial’ loss of power (reduced power available) is much more common than sudden ‘total’ loss of power. You’re putting yourself in a situation where even the slightest loss of power may wipe out your chances of making the helideck. You’re also heading straight for the side of the ship, with lots of solid steel just waiting to readjust your rotor blades. You’re also making a go-around more difficult, because there’s a damn hulking big ship in the way…
a. If you fly a ‘low approach’ slowly into the bargain… you are really in no position to deal with an engine failure. You are going to crash into the water! Pure and simple.
b. If you fly a ‘low approach’ more rapidly, sure, you may have some air speed, but you’re still going to be in the avoid area. You might spend less time there, but… And also, your judgment when to ‘lift up’ onto the helideck had better be right on, with all that nasty steel rushing towards you!
Note that I spent most of a whole night up with one pilot, discussing this one. He was a high time pilot, with 8,000 hours.
He was also very vocal, and influenced many new tuna pilots with his strong and dogmatic views. He tended to get rather angry with me, when I dared to disagree…
In a nutshell, he always flew his approaches ‘low and fast’. And that is what he strongly advocated. In his words; “If there is any problem, I am going into the water! ” He meant “under control “.
I have my -serious- doubts, and I really did not agree with him. Low and fast? Split second reaction time? But you will still not have enough speed/energy to be able to carry out a cyclic flare, like you do at the bottom of an autorotation. I wonder very much if you have the time to react correctly. So,your engine fails. What are you going to do, now you are low and fast? HOW are you going to go into the water? Try a flare? Ouch! If you have not got the speed, you will not have the required energy. You will most likely ‘fall through’ the flare, and crash heavily. I imagine you would hit hard, tail rotor first…
Will you try a “constant attitude splash-in “? Level the skids, and pull everything you’ve got just before you hit? Yeah, right! I’d like to see you get away with a 30 knot ‘constant attitude’ ‘splash-in’.
2. Super low approach
Double ‘Brrrrrrrr!’ What on earth are you doing down there? Looking for tuna?
Why? You’re going to be pulling lots of power, you may well lose translational lift a long way off, you’re practically ‘camping out’ in the avoid area. And if you do have an engine failure, it’s not going to be any fun from a height above the sea of 6 to 12 feet. Your reaction time will be almost nil. Added to this, if you’re not experienced, (and even if you are experienced), you should be aware of the various optical illusions that come into play over water. People ‘fly into the water’ all over the world, in every conceivable make and model of flying machine, remarkably often, with no engine failure at all. Just pilot failure. More on this later.
What are you doing down there? Come up!
If you’re flying a Bell 47, or an R-22, two up, on a hot, humid day, start thinking about your density altitude.
You may simply not have the power available to hoist yourself ponderously up to the level of the helideck.
Even if you DO have enough power, this approach method will extend your “deck edge crossing time ” (DECT).
That is that critical time during which your disc is beginning to cross the deck edge, so now you are committed, BUT you are not yet over the deck, and therefore unable to rescue an engine failure,or loss of power…
By the way, DECT is a term I made up for the purpose of this manual, you will not find it in any other text book.
In general, the shorter your DECT, the better, both on take off and landing! You don’t want that to last for half an hour, when you can get it over with in a few seconds.
Conclusion for the ‘Super Low approach’?
Double and quadruple ‘Brrrrrrrr!’
3. More or less level (with the helideck) approach
Maybe now we are getting somewhere. Maybe you even think that this is the way to go? If you do, you have a lot of company. So do a great many tuna helicopter pilots out there. Remember I explained above that I include a shallow approach (a slight, slow, descent) in this category.
Hmmmmm….. Don’t like it….!
You may wonder what I have against it. Broadly speaking, a lot of the points I made above still hold true.
Remember, you can always give up height. Surrender it. But you can’t always get it back, if you need it!
The more reaction time you can give yourself, the better. Using this method 3), you are still poorly placed to handle any sudden power problems or other mechanical problems. You are still using more power than you need. Your chances of making the deck with sudden problems are reduced. Your ‘go around’ -if you suddenly have to make one – is going to be much more of a handful. You will likely need to pull a lot of power…
Also, if you use this method, (remember, we are talking about a reasonably calm sort of day) you will likely lose translational lift while you are still unable to reach the deck. You may suddenly just not have any more power.
Now what are you going to do?
You’re still twenty feet from the deck edge, only four feet above it, but suddenly going down rapidly…
You -just- can’t – make – the – deck…!!
4. High approach
Go Up, my friend, go UP! A better name for this would be “Normal Approach “, but if I had called it that earlier, I would have given the game away! And I really wanted you to think about it yourself…
Make your final approach a definite, smooth, ‘constant angle’ descent down to the deck.
You do not want a horizontal sideways hover landing with a high power setting! (And certainly no big left pedal inputs on short finals)
We are looking for a stabilized approach, no big changes in attitude, with a gentle, smooth, but positive rate of descent of 300 to 500 feet per minute. You should not be using a whole lot of power at all. That’s good, it means you have a whole bunch in reserve, just in case you should need it!
Your starting point can be where ever you fancy, but personally, I like to be up there! 300 feet, 400 feet, 500!
I am in no hurry to come in for a landing, dragging a whole armpit full of power, with very low airspeed, and starting my approach at forty feet above the water. You will see me draw alongside at a height of hundreds of feet, not dozens, and shush down the approach smoothly and briskly. Plenty of airspeed, nowhere near losing translational lift. A very moderate power setting, nowhere near pulling everything I’ve got. A nice, constant attitude. A minimum amount of time spent crossing the deck edge. (Minimum DECT) . No flare. Nothing dramatic. A nice approach and landing is a most ordinary, hum-drum easy going affair.
Any pilot reading this who has experience in, say, the offshore Gulf of Mexico Oil and Gas environment, will have no problem recognizing this approach. We fly it here all the time. To platforms as well as to boats.
On the North Sea, even when flying a big old bus like the Super Puma AS332L, this was the way the approaches were flown. The Pumas don’t do a HOGE high power setting approach. And they have two engines. So why should you, in a single engine? On the North Sea, we would start our approach from well up, 500 feet or higher. We had a ‘Landing Decision Point’ (LDP) which was 100 feet (above the helideck) and 40 knots. The distance out horizontally from the deck depended on wind direction and strength. Once you flew though your ‘LDP’ you were ‘committed’ to the landing. Sudden loud noises (or loud silence…!), warning lights, bells, etc, were to be ignored! You just had to concentrate on making the deck. Training on the three axis simulator, in Stavanger, Norway, was of course a riot!
On the ‘tuna fields’ you can actually adopt a similar method. What should your LDP be? It depends on you, but 100 feet above the height of the helideck is a pretty good point. Speed depends on type, but 40 knots is not bad for a Hughes 500. Maybe 30 for a Bell 47. Whatever you are comfortable with. It should be well above 20 knots (nowhere near loss of translational lift), but not so fast as to require a horrendous flare at the bottom. In the Super Puma, we would verbally announce ‘LDP’ to the other guy, meaning ‘committed’. Mentally, even flying a small ship, I still click off my own ‘LDP’!
Hang on,you may say, I can still comfortably perform a ‘go around’ at lower than 100 feet.
True, but why should you? If you are coming down, and something starts making nasty noises,vibrating horribly, or generally scaring you, is your first instinct to climb back into the sky?? To see if it is really going to try and kill you?
That sure isn’t my first thought! I’d rather be coming in comfortably high over the deck edge, knowing that even if the donkey quits completely, I can still more than likely ‘shush it on’ somehow. Get down! Then ask questions!
Do you see what I’m trying to get at? Failures often occur when you start pulling power. That extra demand is what does it, and some part says: “Okay, I’ve had enough! ” It follows that ‘where and when’ you start pulling power is important in terms of the relative position of the helicopter to the helideck. The helideck… that lovely place called ‘home’ where you can walk around, all nice and dry, and look at broken bits of helicopter, and say “By Jove! It’s broken! “
Another way… of looking at it is this way: imagine the worst possible place and the worst possible moment for your engine to quit partially or totally. Now ask yourself, IF that worst-case-scenario were actually to happen to you, where would you prefer to be? Then plan your approach accordingly.
Most tuna helicopter landings you will see, come in too low, often FAR too low, pulling too much power, and putting themselves into a situation that is virtually irrecoverable if something quits working.
Go UP, my friend, go UP!
And there is yet another reason to come in higher, in a smooth, stabilized descent, and not come in level with the helideck, pulling lots of power. It’s a very good reason. It’s also a real good reason to think “steady approach ” and not a “hot dog approach “. This reason is called: “smacking your tail boom off the edge of the deck spoils your whole day “.
In the Gulf of Mexico, over the years, dozens, and dozens, and dozens of pilots have smacked their tail rotor and/or tail boom off the edge of the deck, usually by coming in too fast (‘hot-dogging’) and too low (not in a stabilized approach-descent mode). I have seen plenty of photos, where they have dragged their tail rotor right through the horizontal safety fence, (it sticks out around the deck), or otherwise re-adjusted their tail boom, lower fin, not to mention driveshaft and couplings, in a variety of ways not approved by the manufacturer. It’s amazing how often it has happened, how often it continues to happen, and how expensive it is when it happens.
You may wonder how stupid. If that’s what you’re thinking, then you need to have a serious chat with yourself. These guys weren’t stupid. They made a mistake. And if so many young men can make that mistake on approach to a permanently moored oil and gas platform, then you and I, my friend, being simple, fallible members of the same human race, we can do it as well, especially on approach to a ‘bucking bronco’ tuna tub in the middle of a horrible day on the Pacific Ocean.
You have to remember at all times where your tail rotor is, not just in the horizontal dimension, but also vertically.
If you you get into the bad habit of flaring like a son-of-a-(unmarried lady) as you come over the deck… then I suspect you’re putting yourself on a ‘slippery slope’. You will maybe tend to get lower, and lower. And not realize it. And the clearance vertically of your tail rotor and the edge of the deck may slowly be becoming less. And less. Until one day….
5. ‘Very High’ (steep) approach.
Until you’ve seen it for yourself, you won’t believe this. But there are some pilots out there, who will arrive over the helideck on their boat at 150 to 200 feet. And then just slowly hover on down! It doesn’t get much steeper than that.
The problem is that they are so far into the ‘avoid area’ that if something fails, recovery is likely completely impossible.
We had one Korean gentleman who did that a lot. I shall call him Mister Kim (not his real name). He crashed eventually, but not using that method. He made another mistake, and I will talk about that later.
In some ways this section is crying out for some YouTube video recordings. What may be perceived by a new tuna pilot as being a ‘very steep approach’ may in fact be quite a ‘normal’ approach for an experienced offshore pilot.
Again: most tuna pilots come in too low, too slow, with too high a power setting. If something fails, the chances are they are not going to make the helideck. The trick on your approach is to come in higher (go UP!) , with a relatively low power setting, with a positive rate of DESCENT, and with airspeed comfortably above 20 knots. And always ASSUME your engine is going to fail at the worst possible moment. (And know what you will do if it does).
* * * * * * * * *
So now we have covered some basics. Hopefully it makes sense to you, and you are now in your mind trying to imagine what it’s like to land on a tuna boat. Hopefully I have given you some food for thought.
How-ever… here comes a BIG caution. If you remember, in a paragraph above, I previously asked you:
What different factors can you list that should come into your consideration?
And straight off, you came up with:
Direction of the wind
Strength of the wind
Size and shape of the helideck
All valid considerations. But here is something that you likely may not have ever encountered before in your basic Commercial Pilot training: the ship is moving. The ship is generating ‘its own wind’ as it moves forward. Many will do up to 16 or 18 knots. That’s a respectable breeze for a new tuna pilot. But hold on: the Ocean wind is blowing as well!
We have two different winds mixing it together here. One is being produced by Mother Nature. The other is being artificially produced by the motion of your ship moving forward. More than likely, you have not encountered this before. (Even if you are not a new Commercial Pilot, and even if you a few thousand hours, you may still have never landed on a ship underway. It would really not be a good thing, to be coming in for your first landing on a tuna boat, without having thought this one through. It really is a matter of playing it all through in your mind, before you try the real thing on your own.)
The two winds will combine, and there will be a resultant wind over the helideck. A ‘net effective wind’ if you like.
For the purpose of this discussion, I prefer the phrase:
And this ‘relative wind’ may be quite remarkably different in direction and strength of the Ocean wind.
We are now homing in on an area where accidents happen. For reasons I will explain carefully as we go along.
You will also see another, very important reason later on, why we try and fly an approach with a low power setting, and why we try and avoid coming over the edge of the deck pulling a whole armpit full of collective. I shall come back to this mysterious reason later, which
I shall technically call the “Oh Shit! Now what?! reason “.
That reason – which we shall go into in Chapter 3-B – is tied up with the problem of ‘relative wind’.
For now, just take a moment to really absorb these two important tuna boat truths:
* we are concerned about the RELATIVE WIND over the helideck. (as per the windsock)
* the relative wind is the nett result of two winds, the free Ocean Wind, and the artificial wind the boat generates by moving
Accidents have occurred in this area, and (as I shall relate later), some pilots (even after crashing!) failed to understand the forces at work…
Last edited by Francis Meyrick on October 5, 2009, 8:23 pm