In an earlier post DB asked for comments on his presentation; I have already provided some and, in my last post posed the question:
Now one of main principles contained in the presentation is that there should be no departure from a stable (level) flight until the correct shape is observed (DBs CTB - am I the only one who does not like this). As this is such an important element (for me as well as for DB) I was intrigued to know if the representation (of the correct sight picture) in the presentation was accurate - hence the question that was posed. I have now constructed the perspective drawing and have found that DB's:

1. too shallow is about 10 degrees;
2. correct is about 20 degrees; and
3. too steep is about 35 degrees.

Now I know that this was a presentation with the intent of moving the debate on and had to exaggerate to make the point; however, having had this view provided, do we now need to seriously evaluate exactly what we mean by the correct sight picture approach (the deck ovality)?

Jim

Hi Jim,

That is really interesting. I always though we were about 7 - 9 degrees. I am pretty convinced that the rugby ball as drawn is what I like to see from the CTB. I have to say that the drawings were really done to convince non-aviators in my audience as to the "Concept" of the CTB an I certainly did not measure anything in process. Maybe the middel drawing is too steep when it is replicated on paper.

When we fly to 23 at ABZ I think the CHAPI there is set to 7 degrees (I will check) and the square on the runway which we use as a helipad seems to be at the right "Ovality" - accepting that is in fact a square.

CTB - I choose this rather than anything with the words "Decision" in it as we have passed the ARA MAPT and the "Committal" point for a Class 2 With Exposure" has not yet been reached. If anyone can come up with a better acronym that would be great.

It does what it says on the tin "Call the Ball" but I think as a previous poster remarked it is a bit "Hollywood" even for my tastes.

Hi Jim,

I too am surprised at your figures. Looking at DBs presentation I thought he was pretty close. One thing is for sure is that the 3-5 deg "fixed wing" approach is not where we should be!

I would also like to move away from CTB (sorry DB!). Maybe a better call is "I have the sight picture". That goes back to elementary training and is something we can all relate too.

My other comments will be by PM...



Cheers
VL

The Ctb
 

Problem is:

"I Have The Sight Picture" IHTSP is a bit of a mouthful when you are trying to define the point in space for the purpose of profile drawings and descriptions.

How about the IGP (Ideal Glide Path).

DB/VL,

After your posts I went back and checked my numbers; you are correct the figures should have been: 10 degrees; 20 degrees; and 35 degrees. I have edited my original post.

You could always revert to 'intercepting' and 'established' - at least we all know what they mean.

Jim

Aberdeen CHAPI's are set at 6 degree glide path and do bring you to a 20' radalt hover over the H. With a change of about 5' height at the diatnce of about 10m from the device you go either red green or green white.

T4

Jim

You have my vote!


VL

Request for copy of presentation
 

DB

Can you please send me a copy of the presentation.

Thanks

WBS

Hi,

I need an email address to send it to.

DB

I think we will be going for "Site picture descending" and that will also be the time we suspend the AVAD / EGPWS. However "intercepting" and "established" are two necessary phases - its no good waiting til on the ideal GP before starting to descend - you will inevitably go too steep. There has to be an element of anticipation (Jim's "intercepting") prior to seeing the ideal picture.

I am sure we had this discussion before (but think I lost that time) - but isn't it "site picture" - ie the picture of the landing site,

rather than "sight picture" which seems tautological to me - what else can you relevantly do with a picture but have sight of it?

HC

You had me rushing to the dictionary. I am impressed :)

Please understand the timing of my message and the state I was in - hic!

I did mean "site picture" in my original message.



Cheers (hic!!)
VL

errrrrrrr...... "Sight Picture" I believe is the correct wording is it not?

After all, are we not "shooting" for the deck?

We want to have everything "lined up" similar to the concept of marksmanship.

I'm with you SAS - sight picture means you have the correct visual cues/references - site picture is a photo of the LS:)

Sight / Site
 

I still don't know what "sight picture" means. Would you ever say "hearing picture", "touch picture", "smell picture" etc? If not, the word "sight" is tautological. Calls should be designed to be clear and concise, not tautological. But if we just said "picture" it could mean anything - what we are trying to indicate is that we have the correct picture of the landing site.

Unfortunately for me Google returns 8 hits for "sight picture approach" and 1 hit for "site picture approach", however that doesn't necessarily mean site is right!

Never mind, it will all sound the same in the end...

HC

This is scary....Crab and I agree on something....this is getting all too common I fear!

HC,

I wish to report the FAA and US Army adopted the "Sight Picture" terminology very early on. Now I understand we are two peoples separated by a common language but surely with 8:1 stats you will accept the majority view.

This topic does not relate to EC/SK, the 225 or 92, or Nick Lappos....but I will have to admit the size of windows might enter into this in a limited way.

Gents,

Me thinks yoy lot are losing the plot somewhat.

The key issue here is not getting to the sight picture, or what we call it when we get there.

There real issue is what happens (or does not happen) prior to reaching that theoretical point in space, IE Not descend below MDH, not decelerate below VMIN-NVMC for the type.

To make this work the point needs to be plotted on a profile diagram and that menas a TLA I am afraid.

"You must not descend before the Sight Picture"

"You must not descend before the Intercepting"

See what I mean.

The Point in space, and the subsequent call, should ideally be the same. Using a verb to describe a place simply does not work.

CTB...............before you rush off to your keyoboards TEL ME WHAT IT MEANS!!!! I bet you have the answer immediatley....cos it says what it menas on the Tin.

Like it or not some things stick!!!!!!

DB

Slightly related - I'm looking for some pictures of different oil rigs and the lighting of same at night. Any pointers as to locations of same?

HC,
crab and SAS are correct I believe - the origin will be related to a 'gun sight', not 'eye sight' (though clearly the original term will have been) as aiming for the deck will be a shooting analogy.

Sight / Site
 

I am sure this is the second time I have lost this argument!

DB - your ideas are generally good but you have to lose the obsession with CTB - it will never end up in your or our Ops Manual! If you ask anyone for the primary properties of a ball, they will tell you its round (or spherical if they are posh)

To answer your question "what does it mean?", it means calling your ball to come to heel as if it were a dog. Maybe we should use a whistle instead? Bring on the men in white coats, anthropomorphism of balls is a bad sign...

How about FDP - final descent point?

HC

Agreed,

This CTB has never made much sense to me - I'm sure the last couple of rigs I flew to at night had Octagon shaped green lights around the perimeter, not the circle.

I like the terminology 'Sight Picture'. Whilst I've been generally staying out of this discussion on the basis I feel any approach at night has too high a likelihood of going horribly wrong, if I am to continue night decks, then I feel your standardization and stable approach ideas are good. In order I think

i) Gate Position (1nm 500ft or so, after a short period of stable level run-in)
ii) Sight Picture (Start of Descent)
iii) Committal