Questions about Offshore Helideck Landings

[tiptip]

Hey fellow aviators,


I'm interested on some information about offshore helideck approaches. Maybe some of you are so kind and answer me some questions. I'm a helicopter pilot by myself so I know a little about flying but I have no offshore flying experience.


I want to know how you fly the last segment of the approach from 1nm out.




What approach angle do you fly?
Are you flying a dog-leg or direct approach?
How do you orientate yourself if you can't see the platform itself since the water is in my opinion not a good reference?
What airspeeds are you using?
What are the difficulties you experience?
What helicopter are you using and what region are you operating in?



Maybe you just could walk me through each single step.


Thanks in advance

[Fareastdriver]

tiptip. Ask TipCap.

[maeroda]

What approach angle do you fly?

-Normally last mile inbound is on FAT direct to the ship/rig helideck into the wind +/- 30° according to PC1 or PC2 performance requirements.

Are you flying a dog-leg or direct approach?

-direct, VMC stable approach 1mile, 500ft Radalt (unless flying in the NSS)

How do you orientate yourself if you can't see the platform itself since the water
is in my opinion not a good reference?

-you can't land on a platform if you can't see it, see above.
-The helideck and ship's structures are your references.
-With experience you will pick up references from swell see spray also.
-For IMC/IFR LVA we perform ARA's on offshore destination, decision range/MAP is about 0.75Nm from landing installation.
-Extensive use of weather radar and GPS is implemented to get the correct FAT inbound in poor vis and ceiling.

What airspeeds are you using?

-none, using GS (checked against IAS and reported W/V). On AW139 I use 90IAS or 70GS down to MDH, then 70GS or Minimum FD speed hold +5Kts.

What are the difficulties you experience?

-mostly is to do all things in the right sequence, without unnecessary hurrying things up. Night landings could be difficult as well as ARA final approaches at minimums.
Mountain flying is far more difficult than offshore flying.

What helicopter are you using and what region are you operating in?

-Aw139, Europe and Africa.


Cheers.

[Devil 49]

What approach angle do you fly?
Steep and slow.

Are you flying a dog-leg or direct approach?
Whatever was required and expeditious to fly the final couple hundred feet steep and slow.

How do you orientate yourself if you can't see the platform itself since the water is in my opinion not a good reference?
You must maintain a visual reference with the structure, you can't use the water. There was often structure above or around the pad that can be referred to, checked by yawing the aircraft as much as necessary to eye-ball the pad against the approach. Or you can put the nose in the wind and fly the approach in a crab. Or, and this was my favorite, you can fly a curving approach with the final held by visual through the chin.
Always steep and slow, with the objective of arriving at the hover/or deck without a decelerating flare- tail strikes primarily, but power management as well drives that approach profile.

What airspeeds are you using?
That depends on the aircraft and load. The 206 will 'float' in the decel, so I started the approach at 300' and 55 knots. The 355 is actually easier, I could hit the angle at 65 knots, reduce power, pitch nose up for a very gradual continuous decel, and largely hold angle and rate of closure with collective until the hover.

What are the difficulties you experience?
Minimal structure helipads, referred to as 'toadstools', could be hard to keep in sight. Bigger structures generate turbulence in winds. Cranes in operation and gases being vented had to be considered. Where is the pad access? turn the tail away.
Ships, boats and barges have unique challenges.

What helicopter are you using and what region are you operating in?
20 years ago. the Gulf of Mexico. BH206, AS355, BH412.

Offshore is one big forced landing area. The wind is easy to read, especially using the Beaufort Scale. Don't rush, fly it steep and slow.

[paco]

Something like this? I prefer a steepish approach myself:

http://www.captonline.com/H6.jpg

Starting into wind to a point outboard* of the helideck, with the rotor tips clear until you approach this position at around 50 ft above the deck elevation (or 40 feet for the EC 225), with around 10 kts of groundspeed and a minimal rate of descent (around 250 ft/min is good, which is 20 feet per second). In Dubai, with the 212, we started half a mile away at 600 feet, 60 kts, 500 50 kts and so on. When you get to the point where you don't have enough momentum to nose over is when you go for the deck.

*Even though it is outboard, the aiming point is at the far edge, so there is something hard to land on if you need it.

Most operations manuals would probably state that the rotors should be “close to the line of the deck edge”.

Then pass over the deck edge and into a hover over the safe landing area. This way, if the engine fails before the DPBL, you can carry out a smooth nose over, and set your power for the flyaway. If it quits after DPBL, you already have a level aircraft, power set and no need to be nosing over or flaring.

phil

[tiptip]

Thanks for the information!

@maeroda:


Is the view to the landing site blocked by your cockpit and helicopter structure? Since form what I've seen the AW139 has a quite large nose-up attitude while decelerating.
Thanks for the details. Helps a lot!

@Devil_49:


At what altitude are you when you're 0.75nm out?
Great information from you as well

@paco:


Love that illustration
The point you're aiming for is still a part of the helideck or a a couple of feets outboard? So if you're losing an engine before DPBL you would actually clear the structure of the helideck if you loose to much altitude?
Thanks for the help!

[TeeS]

Hi Paco - nice one. The only thing I would like to question, is the use of 'DPBL' as if it is a 'decision point before landing' rather than a (defined) point up to which the flight path can be predicted. An engine failure after that point and during any period of exposure would not necessarily guarantee a landing on the helideck.

Cheers TeeS

[paco]

tip tip - we would aim for a point outboard of the decks with the rotor tips clear until the commital point so, yes, you can always nose over until the last minute.

Good point, tees - I will include that in our lessons.

This is my comfort zone....

http://www.captonline.com/CF.jpg

[Devil 49]

@Devil_49:


At what altitude are you when you're 0.75nm out?
Great information from you as well


Three hundred to five hundred feet depending on conditions, maneuvering to intercept the approach angle at approach airspeed. Airspeed is more critical on a steep approach than altitude.

To be honest, I seldom look at the nav display if I'm in sight of the deck. I'm busy 'seeing and avoiding' traffic, watching wind and weather, but mostly looking at the structure for hazards and turbulence indications.

Deck design, structure and location relative to the wind present more challenges than the approach itself- an approach is an approach after a couple hundred repetitions. Except- always plan an abort! doing it twice is better than doing it once, badly.

An elevated deck clear of other structures with horizontal safety solid surface fences and an access way on the upwind side is easy, smooth air until the last few inches. If the safety perimeter is 'dished' (higher outboard of the pad) chain ink or other material that allows free air passage, exact skids down and alignment become more important. 'Dished' solid perimeter gets interesting at a 3' hover.

A pad directly on the structure roof without a solid, flat perimeter overhanging the vertical walls below or with minimal breezeway underneath can be very challenging with any air at all and impossible with a stiff breeze.

[maeroda]

@maeroda:
[LIST]
Is the view to the landing site blocked by your cockpit and helicopter structure? Since form what I've seen the AW139 has a quite large nose-up attitude while decelerating.
Thanks for the details. Helps a lot!


Regardless of the type of operations being conducted, the basic rule in every approach to land is to have the touch down zone as well as relevant obstacles in sight well before the LDP / DPBL, right?

Depending on wind direction versus deck orientation landings can be made from either seat provided there are two pilots in the cockpit and applicable RFM limitations versus performance requirements.

If vessel heading is 300° and wind direction is 330° thus right seat landing should be selected.
If vessel heading is 300° and wind direction is 270° then lest seat should be selected.
Normally the landing might be executed by the pilot having best view on the touch down and who is closer to the deck obstacles or these obstacles closer to the deck surface.

[Reefdog]

Phil
You know you were not suppose to take photos offshore especially of refuelling places like JJ at swf and by the way I reckon that is a bit steep
I used the end of the pitot tube and 60 knots at 500 radalt to start with and fly the sucker down the imaginary string line.
Slightly off to the left for right seat landing in case you need to go round but close enough to the deck, to get it on if it turns to poo.(bad vibrations and/or noises etc).
That is in a B-212.
AW 139 slightly different but not much, I might add that a little to much attention is paid to looking inside and NOT outside in the AW 139 by most company check & training dept,s.
Know a bloke that nearly landed off shore with wheels up because of the above. Lucky the radio operator was watching him on approach and starting yelling in the radio at 50 feet off the deck. Wasn't listening to his Cojo and the check list either.
Believe he was the head of training too.
Slightly embarrassing.

[albatross]

500 feet above deck at 1 Nm gives a 3 degree approach. +_.
However having said that..if VMC that is just a good learning tool ..in olden daze a curving approach was good...leveling off at 1/4 mile but then the "powers that be" decided that into wind at 1 mile constituded a "stabilized approach" even if that put the pad on the other side of the rig because a crosswind approach was now beyond the capabilities of the crews. How we did approaches to runways back at base in a crosswind was a miracle!
I was amazed when I went from bush flying to offshore. It all became so complicated. A FPSO is just a long hill with a confined area at one end. I have had new offshore pilots from the bush look at the FPSO and say .."I will do a crosswind approach with a good overshoot to the left" All commom sense .. Vs others wanting to approach directly into any wind because "you must approach into the wind".

[paco]

Hi reefdog - you've obviously been there :) I must say I prefer steepish to shallow, especially in something like the 212 - having some gravity behind me. If the approach is managed correctly there's hardly any collective movement at the end, if at all when all the vectors line up. I just applied mountain principles.

I hear you about looking outside!

phil

Phil

[SASless]

Ah....the never ending argument about Offshore Deck Landings.

There was a time when flat, fast, and rapid deceleration was a method advocated by some.

That contrasted with the steep, slow, and slight deceleration method.

What got lost in the harangue was whether the aircraft was single or multi-engined.....and where the aircraft was being operated.

Of course we also had the "Navy" faction that said one had to come to a hover adjacent to the Deck and translate laterally to land on the deck.

Old Bush Pilots saw the Decks (moving or stationary) as mountain top pinnacles and just got on with it.

Depending upon your "Authority", Operator SOP's, and actual situation....probably each of the different versions make sense at some point depending upon wind direction, wind speed, mechanical turbulence, Flare Stack location, movement of the deck (if any), obstructions, presence of work boats, cranes.....etc.

In multi-engine helicopters I prefer steep slow approaches directly to the Deck into (or as nearly into) wind. In single engine helicopters....I like to carry some speed until the last bit of the approach.

But then I flew before all the new fangled rules got promulgated.

The bottom line for me was to ensure I made it to the deck (multi-engine) or had the ability to perform a good autorotation (in a single) without placing the Rig or anything around it in danger. I also did not like large attitude changes near the Decks as that prevented hitting the deck with the tail or tail boom.

I did not care for the flat fast, Gulf of Mexico approaches at all.

[SARBlade]

I think that company Standard Operating Procedures (SOPs) capture the differences stated above. All companies develop procedures for the aircraft flown taking into consideration aircraft type, environment, safety, CRM and company/regulatory wide rules. Generally, all approaches are the same to .75 NM, from this point the aircraft is in a stable approach, visual with landing area and into wind. Prior to that, if IFR, then the standard ARA is method of let down, VFR, well its usually the most comfortable approach from altitude to get the aircraft to that final position. The last .25 NM takes the aircraft usually into the "gray" zone for safety because of the aircraft's OEI performance. This is where technique plays a role in that; do I stay on a final transition to the hover that is outside the fly away capability (higher and slower), or do I go a little quicker and a little more flare in the end (fast and shallow). Much discussion can be generated here because of the different aircraft flown. I flew both 92 and 76, I prefer the 92 slower approach over the 76's faster approach. Anyway, I guess what I'm adding here is that its not a simple question that the OP asks. All the answers you'll receive depend a lot on the factors I've mentioned. One thing is for sure, you have to have good references to land, otherwise its a go-around for sure.

[maeroda]

@Albatros,

I mentioned "stable approach" at 1 mile as per SOP's callout and beginning the descent at 1 mile @ 500 RAD makes the approach far too shallow for my taste.

In real my figures are 500ft RAD, 50 Kt GS, .5 mile from the touch down; then 400ft RAD, 40 Kt GS , .4 mile.....and so on to make a slow and steep approach with only small manipulation of collective stick.

Faster shallow approaches where made in the NSS by dutch people, takes a while to get used to and I'm still asking myself where's the reason of all that tail dragging on the deck when company asks for SOP slow stable and steep approaches.

[paco]

Some of the helicopter performance manoeuvres are a hangover from fixed wing where speed is important if an engine fails, but the oil companies' own statistics prove that engine failure is less of a consideration than other potential points of failure these days.

[Vee-r]

I think most in the Gulf of Mexico are training (single engine) a steeper and slower approach so as to avoid flaring over the deck and potential tail strikes.

[TeeS]

I do remember one ex-associate of mine (a fairly gifted aircraft handler) who preferred to carry out rig approaches in autorotation to the flare - the basis of his thinking was that it didn't matter whether one engine or two failed, he would still get to the deck :-)

TeeS

[Reefdog]

Tees
In auto,really
I bet that got the rig pigs in the back, attention:yuk:

[Craigt50]

Hi all,

I am about to start my HPPL. I have always been interested in offshore ops. But how do you approach a rig? Fly over and the a circuit approach into the wind? Straight in or parallel approach? When and why do you use them? Any info much appreciated.

Thank you

[Thomas coupling]

Ah, Bless.

[helicrazi]

Can and worms

[Craigt50]

Ah, Bless.

Lol got to start somewhere!!!!

[Thomas coupling]

Craig,

Have a think about walking before you attempt the world record 100m!

To even begin to describe something like this at your stage would be like explaining a heart bypass surgery in detail to a St Johns ambulanceman.

[EESDL]

Craig,

Have a think about walking before you attempt the world record 100m!

To even begin to describe something like this at your stage would be like explaining a heart bypass surgery in detail to a St Johns ambulanceman.

You’ll become familiar with phrases such as ‘sight-line- angle picture’ during your training for Confined Areas and Constant Angle approaches. Throw in a mixture of Visual/instrument technique and flying to PC2DLE parameters and you’re getting closer.
PM your email and I’ll share a link to a night rig approach video

[Thomas coupling]

EESDL he hasn't even started his PPL yet, FFS !!

[Craigt50]

Craig,

Have a think about walking before you attempt the world record 100m!

To even begin to describe something like this at your stage would be like explaining a heart bypass surgery in detail to a St Johns ambulanceman.
it is a fair point. But I was just interested in the methodology.

[Margins]

You’ll become familiar with phrases such as ‘sight-line- angle picture’ during your training for Confined Areas and Constant Angle approaches. Throw in a mixture of Visual/instrument technique and flying to PC2DLE parameters and you’re getting closer.
PM your email and I’ll share a link to a night rig approach video
PC2DLE is an Airbus invention and not an operational regulation

[megan]

Welcome Craig to the take no prisoners world of Pprune. Had you said you were a bottle washer at your local and interested in the aviation business as a bystander the red carpet may have been rolled out.