The 5 S’s of a confined area briefing — Size, Shape, Surroundings, Slope and Surface — provide a simple but essential framework for assessing a landing site. Jonny Greenall explains what to look for before committing a helicopter to a confined area and why getting the briefing right matters.

The 5 Ss of Helicopter Confined Area Operations

So here is another acronym used in helicopter training. It is also in the EASA Helicopter Flight Training Manual and many of their excellent safety publications.  Some schools use a different acronym – I’m not here to reteach or say what is right or wrong, just to give more depth on what it is all about.   I’ve also seen 8 S’s and more, which ultimately can be a bit of overkill!

Before the 5 S’s – The Low Recce

Firstly, set yourself up in a recce, about 500ft above ground level.  One common error pilot make is to do a steep orbit over the site – all this means is that you are now complicating the manoeuvre.  You are either looking at the landing zone losing control of the helicopter, or so busy controlling the helicopter that you are not looking at the landing zone.

A nice stable 15º banked turn is simple and gentle and means you can spend time checking the landing zone.  Where possible turn on the side you are seated (so in a Robinson a right turn).  This gives you a direct line of site, and no obstructions or people in the way when making your checks.

Where possible, complete a full 360º orbit.  I can tell you from experience, due to changing light conditions, doing a partial orbit you will miss hidden dangers lurking in the shadows.

The order of the 5 S’s is there for a reason…  Any of them fail the test, it is time for Plan B - go home or land elsewhere.  Any one of the 5 Ss can give you a reason to reject the site. That's not failure — that's good decision making.

SIZE

This is not a test of your measuring ability, or “yes” the helicopter will fit…. 

It is more complex than that.  How big is the landing site?  You might have legal and operational requirements regarding off airport landings to consider.  A high time pilot might be comfortable with a smaller site that a low time PPL.  So it comes down the question:

Is it big enough for me? 

Don't confuse “the helicopter physically fits” with “I have enough usable landing area for the conditions and my level of experience.”

SHAPE

Another common answer from a student – “It’s square” …  congratulations – you have passed your primary school test being able to recognise shapes, have a gold star and a biscuit.

Shape in relation to wind – this is because you want to approach and depart into wind, so a rectangle into wind is good, a rectangle crosswind not so good and you may need to alter your approach profile. 

You need to consider the type of approach and departure – double angle, vertical take-off over obstacles. 

You also need to consider the approach and departure – flying an approach over a town may not be safe, and you might want to change the profile slightly to ensure your approach is safe, and also less noisy for any local population.

You want the safest departure profile as possible, maybe not straight over the lake on climb out, so you can tailor accordingly.

You also have to consider sunlight – low sun in the sky can make for difficult flying conditions and seeing obstacles.

How am I going to get in and out safely?

SURROUNDS

This is both the landing zone and surrounding area; it breaks down into 3 areas:

Things I might hit

trees, wires, masts, buildings etc. and how to avoid them

Things that I might hurt

people, animals (especially horses) and how to avoid them

Reference Points

there is a common tendency to do a quick downwind, turn onto final only to discover you are too high.  Trying to make the landing zone now becomes difficult, if not dangerous. 

Also, when you fly a downwind circuit, it is common to lose sight of the actual landing zone, when you eventually turn final… where is it?

You need 2 reference points:

1 – locating the landing zone – you can use a line feature, or big obvious feature next to the landing zone, so when you turn final, you may not see it, but you know it’s there!

2 – final turning point.  Look up the circuit direction, select a feature that you will use to turn final.  This forces the brain to select something that you normally see from the normal approach perspective, so you will select a reference point that gives you a good stable approach.

SLOPE

Not of great help here, you are at 500ft AGL, you cannot really tell whether it is 3º or 7º at that distance.  It is more of an overview – if the landing zone is clearly unsuitable to land due to slope, then Plan B should be used!  This is much more important in the final stages of approach and hover in the actual landing zone.

All off airport landings should be conducted with a sloping ground landing technique regardless of whether you think it is flat or not.

SURFACE

Again, not of a great help at 500ft.  You can tell if it is tall grass, rocky or completely unsuitable.  You could also consider whether it is possible to encounter brown out in dusty conditions, or white out in snow.  Check for potential FOD in the zone that could become a danger.

Again, becomes much more important in the final stages of approach and hover in the landing zone.

If the landing zone passes all of the above criteria, then you can rollout onto downwind and continue… if not “Plan B” – you have one don’t you….?

The best confined-area decision isn't always finding a way to land. Sometimes it's deciding not to…

This article is intended as supplementary reading for helicopter pilots and students and does not replace your approved training material, aircraft flight manual, operating procedures or instructor briefing.

If you're training for your PPL(H), CPL(H) or FI(H), discuss these techniques with your instructor and apply the procedures appropriate to your aircraft and operating environment.