Helipad Obstacle Guide / Plate (CAT A)

[eurocopter beans]

Can anyone give me info on what various operators use to estimate distances and heights of obstacles in the vicinity of frequently used landing pads? I saw an example of one a few years ago. It was an overhead shot of a hospital pad (non-elevated) with range rings superimposed on it and details below of the obstacles within the various ranges detailed (eg, 100-200M Large tree at 320degM, 90ft AHE). The copy I saw was of poor quality and Im looking for good examples on how to format the info in a clear, pictorial form.

Can anyone provide me with examples of such plates? I am compiling a database of our frequently used sites with a view to providing crew with info about obstacles so that they can select the correct CAT A or CAT B profile for departure and approach.

Any guidance much appreciated.

[Geoffersincornwall]

EC Beans

There are three elements to Cat A:

1. Mass. (WAT Curves).
2. Obstacle Environment (including significant turbulence and or heat pollution from turbine exhausts).
3. Use of appropriate profile.

When talking about operating standards then PC1, PC2 or PC3 should apply if you are talking about Euro-Ops. To operate to PC1 standards you first need a helicopter that is certified to CAT A. Then you need to apply the more comprehensive parameters for the obstacle environment (See JARs). The inability to predict the impact of turbulence and heat pollution has prevented the introduction of PC1 in the offshore environment. The existence of Cat A profiles for offshore (and the use thereof) does not imply that Cat A standards (which must be capable of accurate prediction) are possible. In the same way the use of a Cat A profile alone (without the other two elements being present) does not convey Cat A status on the operation.

The most important factor when operating PC1 VMC is the mass management. Undoubtedly the reduction of take off/landing mass is the most contentious part of Cat A/PC1 but it is the factor that most contributes to the safety of the operation. Of course mass reduction in line with the WAT means lower payloads and it is this aspect of general operations that many pilots are either ignorant of or are simply prevented from doing by commercial pressures.

Use of a recognised profile that has been practiced in the simulator with the rehearsal of engine failure scenarios is likely to produce he best outcome no matter what the mass and probably gives the best chance of stepping out of the wreckage in one piece so don't ditch the profile even though obstacle data is unavailable and you are over the WAT.

In one recent incident I came across the culprits took off 5% over the certified MGW and with the CG 20% behind the aft limit and they had no idea that this was the case. Such ignorance is unforgivable.

So to respond to the thread EC Beans - do you want Cat A obstacles or PC1 obstacles? Are you likely to operate IFR in or out of these sites? It's likely that a plan/photo of the sight from overhead with range rings is not going to cut it by itself. It's a bit more complicated. More accurate obstacle data will be required. All that said there is nothing preventing you from operating Day/VMC using the Cat A WAT and the CAT A profile. I may not be Kosher Cat A/PC1 but it will be a practical solution you can apply anywhere anytime.

If you are going to do the flight regardless then do it at Cat A WAT and with CAT A profile.

G. :ok:

[eurocopter beans]

Thanks for the reply. I will flesh out some of the details.

1.The pads we operate to are inshore.

2.Most of the pads are in congested / urban areas

3. We utilize the Ezweigh software programme during flight planning. This programme (when fuel/crew/pax and cargo variables are inputted) provides us with COG and loading data. We also input atmospheric data before every flight and the programme gives you detailed performance data (OEI hover, OEI + AEO climb performance etc). It will also calculate rejected takeoff distances etc. It is a very thorough and useful tool.

4. The aircraft we operate are CAT A certified and for the majority of our ops, our loadings enable us to operate within the CAT A envelope.

5. We will always plan to attain PC1 when operating into or out of built up area however our regulations do not make such performance mandatory.

6. We have surveyors equipped with laser range finders and integrated GPS, they will travel with us to survey our pads. They, however, have no experience in this type of surveying, and I have no experience in how to represent the info in a simple pictorial format.

The unknown variable in all this are the obstacles around the pad. At the moment we are using the old mark one eyeball to estimate the distance and heights, for example.. "that building is about 80m away and is about 40ft high therefore my TDP will be ...". In order safely elect a departure path (or approach path) and type i need to provide the crews with info on the obstacles surrounding them, especially when the departure is a climbing rearward departure at , say, a 25 degree rearward gradient.

I dont want to re-invent the wheel, i just want to ensure we are operating in as safe a manner as possible, so if anyone has experience in carrying out such surveys to frequently used pads i would like to get some advice.

Cheers.

[JimL]

eurocopter beans,

It is not intuitively clear to me what are your objectives; you are clearly not operating in Commercial Air Transport (CAT) in Europe under JAR-OPS otherwise PC1 would be mandatory in a Congested Hostile Environment (that part of a congested area without a safe-forced-landing area). There are exceptions of course but they would primarily be available to HEMS flights and be subject to additional approval (part of which is the provision of the very charts you are requesting).

I am not an expert at the provision of approach/departure plates but I am aware of the Standards of ICAO. PC1 cannot be flown without a heliport being surveyed; flying within a CAT A procedures bestows no protection on the flight unless obstacle clearance has been established (in which case it is PC1).

Annex 14 requires that a heliport establishes 'Declared distances":Declared distances — heliports.

a) Take-off distance available (TODAH). The length of the FATO plus the length of helicopter clearway (if provided) declared available and suitable for helicopters to complete the take-off.

b) Rejected take-off distance available (RTODAH). The length of the FATO declared available and suitable for helicopters operated in performance class 1 to complete a rejected take-off.

c) Landing distance available (LDAH). The length of the FATO plus any additional area declared available and suitable for helicopters to complete the landing manoeuvre from a defined height.

Notwithstanding Annex 14, Annex 6 Part III and JAR-OPS prescribe a minimum size of heliport - these specify a minimum clear area of 1.5D (greater if so provided in the Flight Manual).

The flight manual (FM) provides: the "Rejected take-off distance"; "Take-off distance required (TODRH)"; and "landing distance". It is for the operator/pilot in planning to ensure that the respective 'distances required' are less that the distances available.

At the end of the take-off distance available (which should be obstacle free) the helicopter will be in a configuration (35ft, Vtoss and positive climb) where climb gradients can be applied (there will be graphs in the FM). Theoretically, provided an obstacle free departure surface angle has been established, it is only a matter of ensuring that the take-off mass will permit that gradient to be achieved (with a miss height of 35ft) to be in PC1.

In practical (and regulatory) terms, if a vertical procedure is used (rearward or sideways climb) to a variable TDP such that (following an engine failure) the min-dip will be 35ft above all obstacles in the continued take-off, the take-off distance available can be ignored. However, it is still necessary to be able to establish TODRH so that the required gradient from that point can be achieved.

It therefore follows that, from TODRH (in distance and height), only the departure angles have to be established - this can be done with relatively simple surveying. If it is found that the departure angle is too demanding to be met within the helicopter's climb gradient, the TDP could be raised - so raising the level from which the climb gradient has to be initiated.

Jim

[eurocopter beans]

JimL,

Thanks for the reply, in response...

"you are clearly not operating in Commercial Air Transport (CAT) in Europe under JAR-OPS"

That is correct, we have no obligation to operate within PC1 and hence no obligation to fly CAT A profiles, however the aircraft are capable of it and the pilots are trained in the procedures so what i'm trying to do is carry out a simple survey to ascertain whether the obstacles surrounding the pad prohibits a CAT A profile (using the exact criteria you outlined) being safely flown.

The pads are not necessarily civilian so have not been previously surveyed!

I'm just looking for examples of how these types of plates are presented in a user friendly format.

Cheers

[JimL]

As I said previously, I have no expertise at producing these charts but, until an expert comes along and puts us both right:

If your helicopter has a vertical procedure (and I note that you have referred to an EC135 in earlier posts) you could:

1. establish the rejected take-off distance required. Superimpose that on your site to see in which directions you can depart/arrive.

2. establish that you meet the criteria for the clear area in the back-up direction (it will be in the FM but, if it is not, see the guidance in JAR-OPS 3).

3. establish the 'take-off distance available', in the direction of departure (a clear area with no obstacles):


a. if that is within the take-off distance required (from the FM) then stop there; or


b. if it is insufficient, establish the highest obstacle in the continued take-off add 35ft and set that as your min-dip and note the take-off distance required.

4. from the TODRH measure the departure angle in the departure direction and check that there is a 1D plus 10% divergence on either side of the departure path (to a max of 7 rotor diameters).

See how many of these clear departure paths you have and choose the best.

Mark them on a aerial photo ensuring that you mark the TODRH circle (it should be the same for all departures)

Mark all significant obstacles (those which penetrate the departure surface).

See how it looks and then decide whether you wish to do it in anger.

Jim

[eurocopter beans]

JimL,

Thats good advice, thanks. Its roughly in line with what I was thinking.

We operate more than one type and any given type has more than one CAT A profile. The type of departure profile used would depend on the distances to obstacles in the vicinity so I want to pictorially represent the height of obstacles within certain radius of the centre of the pad so that crews can elect the safest type of departure for the given environment.

Thanks for the helpful input. I don't suppose you have a sample copy of a pad survey / photo?

EB

[FlightPathOBN]

You may want to look at the FAA doc 8260.42B, which is specific to helicopter operations, so it wades through quite a bit.
Its also allows for Vmini to 70kts, rather than the Class A 90kts.

This is the RNP criteria, so while you can use the containments as allowed, much of that is useless.

Figure 4-5 will at least give the surveyors some guidance on the visual segment parameters.

Another option is to use the PinS type approach for the helipads. This would allow parameters for a surveyed corridor.


The FAA has many helo plates (http://aeronav.faa.gov/index.asp?xml=aeronav/applications/VFR/chartlist_heli) in their procedures database for you to review, the MOS 173 (http://www.casa.gov.au/scripts/nc.dll?WCMS:PWA::pc=PARTS173) from Australia, has plate templates as well.

so I want to pictorially represent the height of obstacles within certain radius of the centre of the pad so that crews can elect the safest type of departure for the given environment.

you would use the standard surfaces that are shown from the end of a runway, but as a circle, there is the 50:1, 34:1, 20:1 for certain distances.

Here is the US Army Helo (http://www.faa.gov/about/office_org/headquarters_offices/avs/offices/afs/afs400/afs420/policies_guidance/memo_TILS/media/TIL00016att.pdf) example

You would probably want to sector this, as to not try to survey too much. I would start with the MET data first for the location, and get the typical prevailing wind directions are a first look...

(you can skype me as well)

[eurocopter beans]

FlightPlanOBN,

Thanks for that. A lot of reference material for me to work off. I will be in touch.

EB

[JimL]

Thanks to FlightPathOBN for the reference to US and Australian Standards; whilst on the subject, you might wish also to look at the helicopter RNAV procedures contained in ICAO Doc 8168 (PansOps) - to avoid being drawn into specific methods of compliance.

Whilst all of this is good stuff it does not address your issue which is more addressed at heliport design rather than airspace. As you will soon discover from this material, heliport procedures are directly related to aeroplane procedures - starting with the assumption of a runway.

Helicopter profiles are much more flexible than aeroplane's in that the TODRH can be displace in the vertical plane, permitting the origin of the departure/arrival surfaces to be divorced from the surface of the site. This provides a real benefit in two ways: (1) it permits the size of FATOs to be reduced to the absolute minimum - so that they only have to meet the requirement for a reject; and (2) as previously stated, it permits a departure into an obstacle rich environment because the origin of the departure surface can be raised above the surrounding obstacles. This also compensates for the somewhat limited gradients that can be achieved by helicopters following an engine failure. (The real benefit of these vertical profiles is that they permit operations from helipads in congested hostile environments.)

In general terms, the airspace (approach and departure surfaces) have their origin at the end of the Take-Off Distance Available (TODA) and, for that reason, have no knowledge of the type of departure/arrival (the original thinking of the ICAO Heliops Panel was that the TODA would contain both the TODRH of PC1 and the acceleration distance of PC2/3).

From TODRH, complexity diminishes because we depart the world of 'profiles' and enter the world of 'gradients' (gradients because it removes the issues of 'individual' helicopter speeds - i.e. Vtoss and Vy - and concentrates on height gained/lost against distance). This requires some work to stitch together the differing requirements of first and second segment climb performance (although I am reliably informed that the AW139 can reach 1,000ft in the time it takes to exhaust the time limit of the first segment (2 minutes).

My advice would be to leave the issue of IFR (entry/exit to/from PINs procedures) and concentrate on the two issues of visual arrival and departure. Once you have a good handle on these, you can graduate to IFR arrival and departures; however at that stage, you will be subject to the issue of formalised survey - as you will if you are forced to operate to Performance Class 1.

Jim

[FlightPathOBN]

Here a a couple of FAA generated charts for COPTER RNAV(GPS)

Indianpolis downtown heliport (http://operationsbasednavigation.com/wordpress/wp-content/uploads/2011/04/06835COPTERR291.pdf)

NewYork LGA (http://operationsbasednavigation.com/wordpress/wp-content/uploads/2011/04/00289COPTERR250.pdf)

just as examples....no approval of the style/info....

[212man]

Flightpath,
useful as your links are - and I mean that sincerely - I think you are mistaking the basis of the question. The Cat A that eurocopterbeans refers to is not Instrument Approach Cat A, but is Aircraft Certification Cat A (See FAR Part-29 and Part-27, or EASA CS29) and, in this particular instance, the performance standards therein.

[FlightPathOBN]

It appears from his question he is asking about obstacles, so they can decide CatA or B...

the plates are examples of obstacles, and the regulatory guidance is for obstacle surveys and areas of survey.

[JimL]

This is a complex subject without much guidance and, what you can find will be quite technical, and difficult to put into practice. As 212man says (and as is illustrated in the procedures referenced by FlightPathOBN) there is a world of difference between an RNAV procedure and a Cat A arrival/departure.

Both of the examples provided have a proceed VFR with a distance between the 'MAPt' and the landing site respectively of 4.1 miles and 4.2 miles (in effect these are what used to be known as cloud break procedures). The Indianapolis insert does provide additional information but it is too coarse for your purposes.

Annex 14 provides a definition of surfaces that should be provided at a heliport, respectively: Approach; take-off climb; transitional; inner horizontal; and conical. If you are interested enough in these definitions, you will find them in Annex 14 Volume II. There are also several 'SketchUp' 3D (SketchUp is a free programme provided by Google) illustrations on the web. (I have used this programme to model the ICAO RNAV PINs profile in order to understand how the surfaces (and obstacle clearance) integrate with the heliport take-off and approach surfaces, in practice. I have also used SketchUp to model transitional areas for Cat A vertical procedures for from/to an elevated helipad)

For a much simpler approach (more in line with your needs) look at Figure 1-5 in AC 150/5390-2B Part 1. You should ignore the notes and, unless you need to understand US heliport guidance, concentrate only on the diagram. This just shows the provision of an obstacle surface (1:25 or 2.29 degrees) for the purpose of notification. If you decide to use this type of diagram and a Cat A vertical departure, you might need to: define your own obstacle surface; and displace the origin of the surface horizontally and vertically to correspond with your TODRH (for the helicopter) and the 'Min dip'.

Because of the difference in scales, you might also need to provide two diagrams - one showing the obstacles and departure/arrival paths surrounding the site and another, similar to the AC diagram.

This is such a complex subject that the ICAO Annex 14 working group have still to come to terms with the implication of the provision of transitional surfaces. (This might also be to do with the FAA approach that the only requirement is to provide a single (and simplistic) approach/departure obstacle clearance surface (8:1) that would be based upon a Cat B departure/arrival -not tailored for the size of helicopter.)

Hopefully, you will soon become the expert - we can then all consult you as the oracle.

Jim

[FlightPathOBN]

Good explanation Jim,

The helicopter designs are certainly a disconnect with the regulators modifying the aircraft regulations, rather than create a specific Cat H design, with specifics to helo operations. Trying to model the 'approach' based on, as you say, a runway, with a CAT A/B final approach speed of 90kts, an 8 second level segment, and a missed for a helodeck is not based in reality.

The plates that I referenced, shown the entire approach procedure with missed and hold, up to 12nm away from the helipad.....the charted obstacles have little value.

In an urban environment, you really have to go with a GPS approach, even if only a series of TF legs, to narrow the corridor down. At least you can have some assurance of the obstacle clearances, and the obstacle validation is much simpler to maintain.

http://operationsbasednavigation.com/wordpress/wp-content/uploads/2010/11/DH1S1.jpg

[Mattb145]

Hi Jim,
Can you clarify more on 'the TODRH can be displaced in the vertical plane, permitting the origin of the departure/arrival surface to be divorced from the surface of the site?

I have found reference to this in appenix 14 but cant quite stitch it all together. The obstacle clearance gradient generally starts at the edge of the FATO and rises out at an angle which creates the initial obstacle surface. This however really doesn't suit a Class 1 helicopter as no obstacles are permitted in the clearway in the direction of flight as their is a requirement for 35ft clearance of the ground OEI until passes the end of the TODRH which is where the aircraft has reached Vtoss and climbing away at 100ft/min 2.5min power.

Is what you are saying is that you can raise the origin of your departure surface, lets say climb the helicopter vertically to 20ft, then start your cat a departure procedure from there? In your approach back to the site you would end up in a 24ft hover instead of a 4 ft hover for example, or in the event of an engine failure arrive over your pad at 20ft and then accept a vertical descent? This is what we 'practically' do in confined area operations but I class this as Cat B as this procedure is not covered in our AFM. Cat B is not approved for inner city operations.

Or, are you relating to increasing you TODP to give clearance of obstacles in your flight path as per the AFM?

Regards

Matt

[JimL]

Hi Mattb (I tried to respond by PM but either your PM box is full or you have not yet qualified to use it).

This has been addressed in the recently constructed 'draft' ICAO Heliport Manual in guidance on the subject of elevating the OLS (the issue you are trying to solve) and the lack of a clearway - necessary in most manufacturer's Category A procedures.

The Manual is due to be published later this year but if you are interested in an early explanation and some diagrams that address the issues, email me (you'll have to work out how to do this - LinkeIn would be one way) and I will try to explain, and show you, how both elements can be achieved with the types for which variable TDP procedures have been provided.

Regards

Jim

[Hot_LZ]

I don’t have access to any at the moment but if you can get hold of UK Mil LS directory they have a standard format for sites that have been surveyed.

Perhaps someone here could upload an example page before I can get to one?

LZ