Elevated Helipads

[DeltaFree]

I have just seen the helipad profile for the EC155. Anyone else seen it yet? It involves a 500fpm vertical (possibly sidewards to retain sight of pad) climb to 100ft, then rotate (TDP).
Any failure before TDP involves a vertical (possibly slightly sideways?) descent back to the pad.
Is it just my tainted view as someone who has used and appreciated a differing slower backward climb that leads me to believe this new method is boll....not so good. You know forward motion, feel the burble of translational lift, reduced power, clear view of pad ahead. It appears now a vertical descent zero airspeed (vortex ring?) poor references plummet is the approved method?
Am I missing something here? Or is the world going mad? :confused:

[zaplead]

This sounds very similar to the helipad profile flown on the EC135 and I have pondered this very point myself.
I can see clear advantages to the 'old' method but the vertical method does make me feel slightly more anxious during take off for the reasons you have cited.......take care, Zap

[Xnr]

Just curious is the EC155 certified Cat A on this profile?

[TeeS]

My only thought is that if the 155 has a good single engine power margin then although the verticle reject might be bottom clenchingly interesting, the rate of descent should be under control. The huge benefit will be the absence of the rearward take off distance that traditional helipad departures require.

TeeS

[Thomas coupling]

The EC135 doesn't have a vertical profile culminating in an engine failure pre TDP vertically back down again:confused:
I suspect neither does the 155. IF the profile referred to is a CONFINED HELIPORT departure, then the helo climbs to 100' vertically (120' for the 135), it then rotates and transitions from there into forward speed. However, should the donk stop, then there is a MINIMUM requirement of 75metres landing space required within which the rejected takeoff profile can be accomodated.;)

[DeltaFree]

The profile I refer to is described as "Take-off fom ground helipad", which I assume is not a confined area or one having 75m or so ahead. Indeed neither of these features are mentioned in the description of the profile.
Judging by other performance parameters for the 155, the weights per profile are pushed to the limits, so much so that use of electronics seems to be the only way to guarantee required climb rates. Therefore I assume again, single engine performance will not be great and a reasonably buttock clenching rate of descent will ensue.
I am looking for the benefits of this profile over an up and back, are there any?
Regardless of single engine performance surely forward motion can only help power margins with translational lift! Most of all though references in front of me are far more comforting than those barely if at all visible below.

[Q max]

These profiles make a whole load of sense ... yea right !!

Oh yes that's right - IF the mechanical problem you have happens to be an engine then you can theoretically land back on.

Anyone remember any basic principles of flight?

How many occurances of one engine failing during one of these profiles have there ever been? Anyone got actual numbers for this? Has there ever even been one?

[John Bicker]

Is the data you are quoting from "approved" or "manufacturers data". There is a big difference. Is this approved flight manual info?

This procedure in the A109E involves a back up with the pad in site to 85' to TDP. Failure prior to TDP is to aim the helicopter at the pad and defend your rotor RPM. At high weights you will see a chevron in the AI at about 15 degrees nose down.
After TDP you may of course descend to within 35' of the departure height i.e. lose 50' getting to VTOSS.

Of course the 109 is a Part 27 aircraft and hence is only Cat A "similar" performance. Cat A only applies to Part 29 Transport Category aircraft.

I don't believe you are reading all the correct data that is available.

Fill us in on the rest.

[Special 25]

In answer to QMax's question, I know of at least one incident. Not technically an engine failure, but the HEMS air ambulance in London was in the midst of a Helipad take-off a few years back, when they realised in their haste to win medals, they had forgotten to start one of the engines ! Being in the centre of the East End of London, and on a roof-top helipad, in a fairly underpowered Dauphin, I am sure the ability to go visually forward and down to the helipad assisted with the whole recovery to Mother Earth !

[Q max]

... of course THAT couldn't happen in a single;)


But seriously has anyone ever heard of anyone ever benefitting from that ridiculous 'reversing upwards' manoever ?

[MamboBaas]

Special 25
I think you'll find that your story is not quite right. Both of the engines were in fact running, but due to a breakdown in CRM (possibly caused by a bit of personal animosity between the 2 pilots), one of the engines was at ground idle and was rapidly advanced to the flight gate when the crew realised their mistake. HEMS subsequently ceased operations for a few days whilst they carried out a review of their procedures.

[Thomas coupling]

Qmax: what are you on about:confused:

These profiles are designed around engine failure, they are calculated to provide for a recovery from an ENGINE FAILURE!
They are NOT designed for other malfunctions - no one can build in a design for every single malfunction - can they?

Going up and back is the best way of securing a safe landing in the event of an engine failure during takeoff, because (a) you've just flown that route, and (b) you know that the landing site will accept you! Thats why it has been designed as such. If you simply transition fwd, then you don't know what the landing site will be like when you touch down from an engine failure, do you? And you'll have less control over your fwd speed before you hit the deck.

Do you think someone simply 'took a fancy' to designing a peculiar launch profile for the fun of it???

If an engine is going to stop, may I suggest the best time for it to fail, is during the take off, when pressures and temperatures are high and low respectively.

[Q max]

.... sure I understand the principal.

But has it ever been of use?

How many examples of an engine failing in this narrow time window have there ever been?

Can you name an example?

Any?

How many up****s have there been as a result of this dogmatic approach? (probably several!)

In fact there's one in a 355 on the AIDS data base where the tail rotor failure would (IMHO) not have been a problem if they had speed. - There are many ways to skin a CAT. To deliberately prolong such an energy inefficient state of flight - in the process exposing the A/C to other vunerabilities - on the off-chance that a favorable theoretical chain of events might occur is obviously mad.

TC: there are millions people who believe that banging their head against a wall till it bleeds has religious merit. - very difficult to change their minds, they do it because they were raised that way (i guess) - you're not one of those are you?

[rightpedalRIGHTPEDAL]

To Delta free

The Dauphin profile goes to 130 feet for whatever reason, 'H' in the chin bubble, and in training works fine. Having said that I wouldn't like to lose a donk at max Cat A loads ISA ++, in between the pad and CDP - I think it would be interesting.

[TeeS]

Q Max - yes I had to make use of the full procedure and reject back to the spot several years ago. It actually wasn't an engine failure but a transient surge caused by a biscuit wrapper sucked into the number one engine. I have to confess that at the time it happened I did not have a clue what it was, there was just a bang, a fierce judder and when I looked down all the engine indications were normal. At that moment I was just very glad that I still had the aiming point in the chin window just where it was in all the base checks. I know that both engines were still running but the power required was very low and I am confident that we would have been OK single engine.

It was a very very tight site in the middle of Birmingham with nowhere else to go - In the circumstances we could have flown away quite happily but that was knowledge only gained during the post incident engine inspection. If the engine had failed for real we would have ended up on the railway line if we had not flown the procedure.

Cheers

TeeS

[Shawn Coyle]

Category A procedures are based on trying to achieve a level of safety that is predicated on engine failure probability. Currently the expected failure rate of an engine is once every 10,000 hours. So for Part 29 helicopters (and those Part 27 machines that decide to use Category A), something has to be done to ensure the level of safety is met. Body counts of more than 9 get civil aviation authority leaders (ministers, administrators, etc) in hot water, so the end result is the Category A procedure.
It does not address everything, and someone said, no procedure can.
The Category A procedures in the FM are tested and proven by the company and the certification authority in the country of certification. In some places, the certification authority in the country of use will verify them. They are generally conservative and give margin for error and abuse. The procedures must be read in conjunction with the appropriate limitations of the supplement / section of the FM. If it says there is a size limit on the helipad, then that's a limit.
Have an accident doing a Category A procedure to a helipad that is smaller than the minimum, and you have just invalidated your Cof A and your insurance.
As for the backward takeoff - has anyone looked at the Bell Helicopter sideways slide technique? Easy to use, little loss of performance and very repeatable. Also much easier on the passengers...

[DeltaFree]

The vertical profile for the 155 is taken from the FM and marked DGAC approved so should be CAA approved with little or no changes.
I feel happy with the up and back procedure I have practised before, but am still inviting anyone to sell me the advantages of this vertical profile. Yes yes I know it is tried and tested, but what are the benefits? I may be missing something obvious not having tried it. I await my education.

[John Bicker]

DeltaFree,

Maybe this procedure is all the aircraft is capable of demonstrating. If you do the "backup" manouevre it won't get back to the pad. It would sound that it is possibly of little benefit but it is there. Is there not another page in the manual which refers to this procedure like the "corrected weight" pages often found in Eurocopter flight manuals.

It is difficult to understand your concerns without information as to how the procedure is determined.

On the original Puma all this procedure was based on pitch angle and timing there being few other usable cues to the pilot.

The procedures for the Cat A vertical can differ from type to type and are not "generic". They are published in the flight manual. It would be interesting for you to post the useful load that is claimed for this procedure at say S/L ISA+10.

Maybe EC have not developed a procedure as yet. I know for a fact that the certified envelope has not yet been extended to the true capabilities of the aircraft. There is a 155B1 in the wings.

[TeeS]

Delta Free
The current short field/helipad profiles require either a good clear run on area in front or a clear gradient behind, all fine and good for a pre-planned hospital site (if you can get them to give up the parking spaces!) or nice hotel helipad. However what about landing at HEMS sites etc. where a traditional helipad profile can't be flown because of surrounding lamps and buildings.

Surely, if the test pilots have come up with a vertical profile that we mere mortals can cope with and the aviation authorities are happy then it must be better to have that profile available. Lets face it once you have loaded your patient onboard, if the only way out is straight up then that is the way you are going to go. At least if there is an appropriate profile you will have practiced it and have a pre-planned decision point, that has got to improve your chances if you are the unlucky 1 in 10000.

TeeS

[Thomas coupling]

I bet that stole your thunder, Qmax?

If you were to design a CAT A helipad departure, then, how would you do it?

[Q max]

So to conclude no one knows of an engine failing during this period !


Sounds like classic "This is the way to do it" - pet theory of one pilot gone mad - someone said MACS invented this nonsense - true?

(TC : I'd try and look at the actual risk factors during t/o and optimise for those - it obviously would put this non-existant risk quite low down the list of influencing factors on a t/o profile)

[TeeS]

Q max

To help convince us of your argument why don't you list all these actual risk factors that you wish to optimise for and then tell us the profile you would use to negate them. I'm not talking about operating from a clear area such as an airfield because we don't usually fly these profiles then!

TeeS

[vorticey]

tees summed it up but i agree with deltafree, it sounds like an old wives tale!
sure you can see the helipad but do you need to? what about that tree (building or ariel) out the window? and if youve got room and power to back up downwind when towering, why not back up along the ground and tower foward reducing the power reqired,
when these cat A takoffs are used, do you need crewmen hanging out the window watching the tail? and why 100 feet, the less time spent towering the more safer i would think.

remember vortex ring state needs just a little airspeed and a quick decent, just the right mixture.

Shawn Coyle : can you explain the bell slide technique?

[soggyboxers]

QMAX
Not quite the same as a helipad, but yes I have had an engine failure immediately after rotating during an offshore towering-type take-off, so it can happen and has.

During the 1970s Bristow used a verical take-off profile from the Wessex for use when taking off from helipads in the jungle/swamps. It had the advantage of getting you back on to a known safe area i.e. the solid wooden/concrete helipad from which you had just departed. I seem to remember that the procedure was to climb vertically to 200 feet and CDP was at the point of rotation. Provided you used a lateral reference for the (slow) descent the only problem was usually in the mind of the pilot involved, as before actually carrying out the procedure it seemed as if it might be a bit hairy. The Wessex had much worse downward visibility than most modern helicopters, so I guess that once the procedure has been practised a few times it may not seem as bad as it looks from just reading about it in the FM.

[Q max]

I guess the extra risks are being run just for the sake of theory then ?

Surely some one must know of an engine failure actually happening during this 'backward' climbing phase - anyone?

I'd expect there to be at least one freak occurance of this dogma actually being useful !


Soggy: after rotation right? Would you still have had a problem if you had been using the energy you 'wasted' by climbing (at such an inefficient speed) to accelerate to efficient translational lift state?

[TeeS]

O.K. Q max, you have finally convinced me. I have been doing it wrong all these years and will not be doing any more helipad profiles.

Please can I have the benefit of your experience, how should I go about departing from a helipad that is surrounded by houses, a hospital and an office block?

Thankyou in avid anticipation,

TeeS:rolleyes:

[Thomas coupling]

Qmax: you're not answering anyones questions. There is an overwhelming appreciation of these profiles. Where on earth did you hear that MASL designed these..do they have an international mandate on takeoff profiles? Do they supercede the manufacturers design criteria? These profiles have been around for years and are designed for I REPEAT: engine failure.
if you still refuse to accept that some people have had engine problems necessitating the use of this profile to get them back to earth safely, then shall we scrap them then because there are no engine failures during t/o any more and never will be :eek:

Please answer the question:

WHAT WOULD YOU SUGGEST WE USE QMAX....

Armchair judging again, methinks....always ready to criticise but nothing constructive to add to the conversation:rolleyes:

[DeltaFree]

I asked if anyone could tell me of any advantages to this vertical profile. I guess for the pure flying side there are none, but it is clear that HEMs have a need for such a profile. I am sorry I do not have the rest of the FM as this profile was just shown to me by a mate, but I assume the vertical requirements will be harsher than an equivalent up and back. I guess none of us want a different profile for every conceivable departure so it is fair to replace the up and back for a towering one. Am I right?

[soggyboxers]

QMAX,
You're obviously not familiar with offshore towering take-offs. Yes, I'd have had a lot of problems as the immediate sink whilst I was trying to accelerate forward would undoubtedly resulted in my striking the deck edge with my tail and pitching nose forward into the sea before 'accelerating to an efficient translational lift state'.
All of these certificated vertical and rearward take-off profiles have considerable restrictions on the permitted take-off weight to allow for the performance deterioration whilst flying them and are intended for the many times in helicopters where space considerations do not permit acceleration with a safe single engine reject before CDP using ICAO Class One performance criteria (or Group A/Category A or whatever one is using) to ensure that it is possible to reject on to an area where a landing may be made without damage to the aircraft, its occupants or third parties.
Just because there may have been no recorded instances of an engine failure when these profiles are being flown does not mean there never will - Mr Murphy will always be around to guarantee that.
I think you are suffering from the Australian ostrich disease and burying your head in the sand when confronted with things with which you either do not agree or do not understand.
:eek:

[Shawn Coyle]

Consider the same sort of thing in FW airplanes. The airlines schedule their performance, weight and so on to ensure they can always either stop safely on the remaining runway, or continue the takeoff and climb safely. They often take a performance hit either in weight or engine life (can't necessarily use a reduced performance takeoff and save engine life).
The Category A procedures are nothing less than the RW equivalent. If we think we can use something that is less safe for the fare-paying public, then I think we're fooling ourselves.
This is not to say that the procedures are perfect, or that we should not continually question why and how they are made, or the assumptions they are based on, but remember this is an attempt to make things safe.
Some of the issues that need to be considered are- exposure times on takeoff; better airspeed indicating systems so we can take best advantage of performance before the pitot system starts to work; better information for determining the decision points; ways to make the charts easier to use; weather reporting at the helipads; better guidance in and out of the helipad; and so on.
But let's not forget the aim - to improve the level of safety to something approaching that of the airlines.

[vorticey]

you said >Yes, I'd have had a lot of problems as the immediate sink whilst I was trying to accelerate forward would undoubtedly resulted in my striking the deck edge with my tail and pitching nose forward into the sea before 'accelerating to an efficient translational lift state'.

surely if you've got enough power to verticle up out of ground effect, you would have enough to stop you falling off the edge. you could even hover over the edge and accelerate from there.
and wouldnt there be enough hight off the edge of the pad to fly away even if one engine failed, rather than tempting vortex ring on the way back down?

[Q max]

... sometimes when there is an intrenched philosophy it is difficult for people who have been immersed in it to see the truth - people start whole 'religions' based on twisted ideas.


Reading the accident reports for twins it is clear that the utility of this profile is insignificant in comparison with the other risk factors (and may actually be counterproductive).

I am happy to start trying to collate them and will make a non exhaustive preliminary stab at it:

1 This profile exposes the helicoter to a high risk scenario for much greater time.

2 Uses the upper range of engine output for considerably longer.

3 Uses a higher relative power output than alternative.

4 The machine is vunerable to other failures, T/R malfunctions, crew coordination, collision.

5 Incresed exposure to control problems - having such a low energy state for such a long period makes the A/C vunerable to the random vagaries of the atmosphere with at least two major controls running near their limits (or potentially near their limits) (T/R and Collective).

6 The greatest mitigator for risk on takeoff is to have a deliberate 'extended hover phase' prior to T/O. During this period the probability of ANY catastrophic event drops rapidly with time.

7 The 'BIG IDEA' of twin engines is supposed to be that it 'doesn't matter' if one fails. If you fly a regime where you actually NEED two engines - then the risk is much higher since there is at least twice the chance that one of the two might let go.

8 Three or more hands required (throttle levers) for longer - reversing the benefits of two independant crew and making it two crew dependant.

9 Increased FOD risk - (look at the accidents)

Is it REALLY worth exposing the helicopter to these EXTRA risks for the return of it being THEORETICALLY possible to withstand an event of such unlikelyhood that as far as we can determine it has NEVER HAPPENED ?

Furthermore it is more amazing that this event does not occur more often since the very profile we are talking about ACTUALLY INCREASES (dramatically) the likelyhood of it occuring!

-----------

Soggy : of course HAD your 'engine event' occured at the critical point in a translating type profile then yes you may well have hit your tail. - BUT clearly the fact of the matter (which you side stepped) is that in your case since the engine let go "just after rotation" you would have had sufficient energy production (especially applied in a more energy efficient manner) to have been at an aerodynamically efficient velocity - such that it would not have been a factor - FURTHERMORE to what extent was the power failure you experienced ATTRIBUTABLE to the profile you were flying?

THEREFORE your case is still NOT an example of that profile being of ant ACTUAL use - only THEORETICAL.

------------

There have been NO EXAMPLES of an engine failing during the climbing up and back.

I asked the most a highly experienced (>40,000 hrs) Rotary pilot (that I know of) weather he ever used this profile in the military twin he flew : He said "certainly not!" and went on to explain why it is the most absurd concept - he though it had been 'invented' by a British operator (MACS or Bristow) to keep their Flight Ops Inspector happy - and avalanched from there.


Yes the twin has a place in risk reduction - but it's not always safer.


To make any true improvements to safety one must be honest to the factors and figures in a scientific way.

The discussion should be in terms of TIME EXPOSED to RISK EVENT (TE) and PROBABILITY per TIME of EVENT (PTE) occuring and PROBABILITY of UNSECESSFUL OUTCOME to event (PUO).

With this profile both TE and PTE increase (and are multiplicative) PUO might (theoretically) be reduced. At the moment only PUO is looked at - this is a major flaw.


I don't really expect anyone to start actually re-evaluating this.

REMEMBER THE STORY OF THE EMPEROR'S CLOTHING ?

[advancing_blade]

Calling Shawn Coyle, Calling Shawn Coyle

As another mentioned earlier, Please could youu give a bit more info' on the "Bell slide technique", this sound interesting

[soggyboxers]

Vorticey,
Sorry, but you've obviously never done an offshore helideck take off. The amount of power you're pulling in the hover (which is often at, or close to, the maximum allowable gross weight for the technique) normally gives a thrust margin of only 2 to 4 per cent. This is enough to allow a 'vertical' acceleration to just sufficient height for the tail to clear the deck in the event of an engine failure at rotation. The 'height' attained in this procedure is only 10-20 feet (dependant on aircraft type), so you're still in ground effect; is done close enough to the centre of the deck that none of the blades is overhanging the edge (to ensure no loss of ground effect); and is sufficiently low that there is no chance of vortex ring state developing. There's also not the slightest possibility of hovering on one engine at the take-off weight you're at, you're just going down. Hope that explains it a bit better.

QMAX
You sound more like a statistician than a pilot - difficult to know as you have nothing noted on your user profile, but it seems to me that you are the only one on this thread who has an .e ntrenched philosophy and you still have obviously not got the slightest idea of what an offshore helideck take-off is like (and from the sound of it no idea whatsoever of what an onshore restricted helideck take-off is like either).
in your case since the engine let go "just after rotation" you would have had sufficient energy production (especially applied in a more energy efficient manner) to have been at an aerodynamically efficient velocity - such that it would not have been a factor - FURTHERMORE to what extent was the power failure you experienced ATTRIBUTABLE to the profile you were flying?
Engines don't 'let go' - to we pilots, they fail. With only 5% torque in hand, I was pulling exactly the same amount of power as I would have in a forward transition type of take-off, and my engine failure was not related to the power I was pulling. Your talk of 'aerodynamically efficient velocity' is just nonsense - I was at a velocity of ZERO having just rotated the nose down from the hovering attitude.
The only vagaries associated with this thread seem to be your vague and uninformed ramblings.
:eek::) :)

[Old Man Rotor]

Wow......such attitude and ignorance can really hurt...........

Yes the CAT A profile does work....and work well..........a few years ago during a final handling test in a HP, the engine failed just at CDP.......well it was a real anti climax as the applicant put his nose down to 15 Deg and raised it up as VTOSS was passed......and the Rad Alt showed more than 35 ft at all stages..........we were loaded with sand and fuel and were at max CAT A weight..........so please talk about things that you have some knowledge about........or ask questions to gain that knowledge......but please don't preach on subjects in which your knowledge is lacking.

I guess your way of doing this would have been to lift and transit forward over the houses or schools or buildings.......then when you have a failure before VTOSS....guess where you are going......yes on the 6 O'clock news.




Offshore Approaches and Departures in every country that I have worked are never CAT A......and I don't think the Offshore Oil Industry anywhere would accept them at all..........A modified CAT B technique is used throughout the industry, and if done correctly will reduce the "exposed" flight time where flight may not be possible, down to a few nano seconds........statistically proven to be safe and acceptable......

[Q max]

As I said: "Yes the twin has a place in risk reduction - but it's not always safer. "

So, yes, under some circumstances twins can actually be safer - the extent and the circumstances are often exaggerated.


Soggy said: "Just because there may have been no recorded instances of an engine failure when these profiles are being flown does not mean there never will - Mr Murphy will always be around to guarantee that. " - sure but if they have never been used and they increase risk in other ways then isn't it fair to look at them again?

If you are exposed in an aircraft which needs two engines both working then the risk is greater than had you only had one.

Old Man: I did express my surprise that noone had benefitted from the use of these profiles - and none had. Obviously you are now a big fan of them. Do you maintain that that was actually a ZERO risk event for you? Hopefully not! - what were you thinking doing a test over "houses or schools or buildings" anyway - or where your "houses schools or buidings" theoretical ones which fortunately, since you made them up, were no taller than 35ft?
Mind you you probably wouldn't make the news by hitting a theoretical building !

Old Man: you said (while being mildly insulting ... but fair enough): "or ask questions to gain that knowledge" - I thought I was asking: Has anyone had an engine failure during the climbing upwards and backwards bit (ie after hover and before CDP (or is it TDP?)) - I guess that's still no-one is it?



But seriously thanks for the education - it's true I had actually forgotten the EXPOSURE time concepts of these CAT B profiles and yes of course the risk is minimal - the greater benefit being derived from the prolonged Exposure to a Hostile Landing Environment - It's a clear example of a single engined aircraft being safer for a short phase of the flight but the twin probably being superior in view of the prolonged exposure time. (mind you.....)

If you just run the calculations in accordance with the published regulations you can compute the exposure time required to make a CAT A twin safer. It is suprisingly long. Don't make me go and look it up again..... I can't be arsed....

The table of statistics (pointed out by Nick Lappos) published on the twins/singles thread clearly shows the higher risk of twins.

Is there a big problem in the Gulf of Mexico from running singles?
- I don't think so.

Finally - yes I am recieving something of an education - in a subject which I do know something (though not much)about - I have actually dabbled at flying a couple of times - but I have to say I am partially tounge in check while pulling the odd leg and seem to have hit a raw nerve.... and I don't really want to offend against anyones 'pet theories' even if they are a perverted bastardisation of the principals of aviating (tongue, cheek, leg, nerve)

If a statistician in a major regulatory authority were moved when 'caught' analysing these figures - would that be a scandal?:eek: ?

[soggyboxers]

QMAX,
Yet again. I think you'll find that OMR was not carrying out a test over houses or whatever. He was merely pointing out that during a check flight, with the aircraft ballasted to the maximum allowable weight for the profile in the prevailing conditions, ON AN UPWARD AND REARWARD HELIPAD TAKE-OFF HE ACTUALLY DID SUFFER A REAL ENGINE FAILURE AT CDP (correct phraseology as it is a Category A/Performance Class 1, or equivalent, take-off). The reference to 35 feet is just standard for this type of take-off as the certificated profile calls for a flyaway with an allowable descent, which must nevertheless clear all obstacles on the continued take-off flightpath by a minimum vertical separation of 35 feet.
Having had a couple of engine failures in twins, which have always resulted in my being able to return to a site at which I was able to make a safe landing; and always in circumstances which would have caused me to make a survivable, but unsafe landing had I been in a single, I still can't see how a single would have been safer. None of these aircraft needed 2 engines, they just had them - or by 'need' do you mean that the aircraft is incapable of flight at, or near max gross mass, on one of its engines?
:confused:

[Thomas coupling]

Qmax: you're not a pilot, you don't understand these things, you never will. Stick to what you're good at, whatever it is and confine your comments to that regime.
Your contributions are becoming embarrassing. :(

[vorticey]

soggyboxers, thank's for the reality check. i was under the impression that every takeoff was done up to 100 feet backwards as mentioned earlier in the profiles from Thomas coupling and DeltaFree. is the takeoff you mentioned classed as a cat A?

Old Man Rotor, i was looking for sombody to pick my thoughts on the matter of backwardly rising 100 feet. somebody said that one engine will slow the decent enough for vortex ring not to be an issue with one engine failure. my main issue was going backwards.
you said: I guess your way of doing this would have been to lift and transit forward over the houses or schools or buildings. you forgot to mention roads, parks and ovals. which ones did you fly over at 35 feet? and if you just lifted and transited foward would the time taken for the engine to fail have let you be in a posible one engine configeration? do you know what happend to the engine?
you also said> Yes the CAT A profile does work....and work well,
and> Offshore Approaches and Departures in every country that I have worked are never CAT A. does this mean you dont believe in using them either?

[soggyboxers]

vorticey,
No the offshore helideck take-off is not Group A, as there is a very short risk exposure time between rotating the nose forward and the tail clearing the edge of the helideck. It is also possible if the helideck is low, the aircraft is very heavy and the wind is light, that the aircraft may have to be ditched if it cannot be accelerated to Vtoss before reaching the water.
This also refers to what OMR was talking about with regard to offshore approaches and departures not being Cat A. Many offshore helidecks are not of a diameter large enough to comply with the size required for a Cat A helipad departure and even if they were, the payload losses resulting from the restricted weights permitted by these profiles render them commercially unacceptable. As the Class B profiles flown reduce exposure times to a minimum, most oil companies and regulatory authorities allow them to be used. This may well change with the advent of newer helicopters which have true Cat A performance on a single engine. However, they also rely on the fact that after leaving the deck there is a clear path over the sea for the continued take-off. This is not the case overland in e.g. EMS work, where a helicopter may be operating from a rooftop or a small field and then the upward and backward Category technique has to be used. You are quite right in assuming that the rate of descent on the remaining engine is sufficiently low that there is no danger of vortex ring. The rearward climb also allows the helipad to be retained in the pilots view at all times, making rejecting back on to the take-off spot fairly easy. The angle of climb is also sufficiently steep that it can be performed in a relatively limited area. Hope that helps to explain it a bit more.
:)

[Old Man Rotor]

Oh Dear........

I have indeed been slow...........

********, Burke, Nutter and ...well never mind.

Just checked my "Inbox Resume" file.........thank goodness you were'nt there........as our shreader is presently broken.

Good luck with your dreams.............

[DeltaFree]

Your last post seemed to suggest that I was saying all CAT A take-offs were up to 100'!
My original question was reference a vertical 100' climb for the EC155, for a Helipad departure, helipad suggests a very limited landing area, hence the requirement for height. Obviously if there is a clear area ahead you get your speed then height. I was looking for the benefits of a vertical climb over the more "traditional" up and back. So far it seems a vertical climb is more useful to a lot of operators although I suspect the weight limitations will be more restrictive.

[Shawn Coyle]

Bell Helicopter 'Sideways Slide'
developed for the 230 and used there and in the 430 Category A profiles for elevated helipads.
Basically you move sideways and up away from the helipad until your blades are clear of the pad plus 15' or so. Sight picture is well defined in the flight manual. No need for any large power increase over hover power. Prior to getting to the Takeoff Decision Point, any engine problems and you go back to the pad- either with sideways motion, or by turning and pointing back to the pad.
After the TDP, just fly away.
LDP is the same place, alongside the pad with the same sight picture as takeoff.
ADvantages are that there are no large attitude changes, no large power changes over power to hover, and it's very easy to make the return to the pad- always in sight and roll is much easier to make large changes in attitude than pitch.
Now if only we could get this sorted for ground level helipads...

[Q max]

Old Man and TC ...

My view has legitamacy, the evidence supports it ... as I said I don't really expect you to change your minds ... but you could engage politely!

I don't really want to p*ss on your bonfire anyway. Live and let live. Each to his own. I withdraw ....

[Tony Chambers]

Just after some advice and opinions. What are your personal opinions on approaching and landing on an elevated helipad? What would be your thoughts on doing the same to a helipad on a sometimes windy seafront.

[BlenderPilot]

Please look at my webpage to see some elevated pads, use the www button above.

I am not a great expert at anything but one thing I do have experience at is landing at elevated pads!

We operate at elevated pads all day long, and at weights and DA's that do not allow for OGE hover so approaches have to be perfectly timed, so that when you lose ETL you have the pad handy to provide some ground effect, but never coming in too fast.

One thing I do know is that approaches to elevated pads should never have a flare at the end, choose and angle and attitude, keep it and decelerate with collective, feel the aircraft start to mush in, if you feel it mush in before time you should use a little fwd cyclic, if you are flaring to stop at the end you are doing something wrong.

For me a perfect approach to a pad should be with almost 70% of the power requiered to hover IGE to be applied long before you reach the pad, come in loaded.

I usually never approach straight in, I always crab myself away from the pad for better visibilty and chances to dive for speed away from the building in case I have to do a missed.

Never come in too flat, and never too steep, especially if you are heavy,

If you are flying single engine be comfortable with the fact that there is a point during the approach that if the engine quits you will have little chance to continue with your life.

Watch for Satellite dishes in not so frequently used pads, I have blown quite a few of rooftops.

Ahh, careful on the really large buildings, those air conditioning exahust vents can push you back or away from the pad easier than you think!

Once you have made it the pad never forget to position the aircraft regardless of wind with the nose toward the access stairs, I have seen pilots just park it against the wind and having their passengers have to walk towards the the TR to descend from the pad.

For takeoff, be really careful if you are heavy, since when you depart ground effect, you might sink fast and hit the buildng with your boom if you are heavy and departing flat, watch you pedal as soon as you depart the pad, in some pedal limited machines like the the 206 L4 if you pull power to avoid sinking you will spin so fast you'll be staring the the building you just departed in a second. If you are heavy or at altitude and the machine sinks, don't be afraid to point it towards the ground to gain airspeed for a second or two.

[rotaryman]

BlenderPilot:

Some wonderful advice,,Thouroughly enjoyed every word...:ok:

[whoateallthepies]

If you are using an elevated helipad in the UK you will have to be twin-engined and operating to Category A limits.

Wind is good = performance increase.

Which pad is it you want to use?

[VeeAny]

Blender

Excellent bits of advice, and some brilliant photos.

Thanks for sharing both.

V.

[sparks and stuff]

Blender Pilot. clicked on the www button and congratulate you on a fantastic portfolio of pics, loved them all. Well worh a browse if anybody has the time.

[NickLappos]

Blender,
great pics, and very noteworthy in that all the helidecks had nearly perfect design for OEI safety (no wall or parapet, safety nets instead). I can't tell you how many pads I have used on rooftops that had a 3 or 4 foot wall around them!

[rotorspeed]

Blender - more plaudits, great pics, great advice!

Really impressed at how many elevated pads you have in Mexico, and number of machines using them. What rules apply for private and public transport use? Can you do single engine public transport on these pads? Is it hard to get planning permission for such pads? Even thinking of it in London would cause absolute apoplexy, not just with the CAA but with locals and planning authorities too. Seems you live in a very liberated society! Green with envy!

What sort of AS and VS are you maintaining on the approach? What height do you start to bleed off the AS?

[Tony Chambers]

Thanks for all the info blender and nice pics. I personally am not looking to land on an elevated pad, but i am looking at the possible instalation of a elevated pad, it is quite near a blustery seafront, so not sure if that would cause many problems. Thanks again.

[The Rotordog]

Tony,

You are "looking at" the possible installation of an elevated pad near a windy seafront, eh? But you're not looking to land on it yourself, eh? So...what, you're looking for reasons to stop it? What's your angle here?

Landing on an elevated deck near a seashore is no different than landing on an elevated deck anywhere else....except that there will probably always be some wind blowing. And that's a good thing.

[Tony Chambers]

Rotordog, i am in no way trying to stop this, i would like to install this. But i am not a pilot so my angle is to find out from a pilots view if there would be any additional difficulties with a coastal elevated helipad.

[md902man]

Hi Tony, Marc Little at Fast Helis, Shoreham, hasn't put you up to this has he? Sounds like the sort of thing he'd like!!

[Tony Chambers]

Nah no1 from fast as put me up to this. Its all my own doing lol.

[Helinut]

Tony,

Going back to your original question, it does not really matter what someone personally thinks - the rules need to be followed. And, of course, because we are talking UK, there are lots of them.

Is this flight to be public transport or private? Is it to be SE or ME? What type of hele?

In terms of location, it matters little that it is on a seafront (in terms of the rules). What surrounds the helipad - are the surroundings a congested area or hostile terrain?

What is the size and shape of the pad and its immediate surroundings?

[Gomer Pylot]

Tony, I've spent over 20 years landing on elevated pads offshore, and have done close to 20,000 - 9000 in about 6 months once. The wind is generally a good thing, until it starts having the flow interruped and redirected. If you do install a pad, try to have a breezeway under it, so the wind can blow underneath, and not be entirely redirected upward, which results in it blowing almost directly downwards on the downwind side, which can make for interesting approaches, and very interesting shutdowns and startups. The main rotors can strike the tailboom easily under those conditions. The worst thing you can have is a completely vertical wall right up to the pad - a breezeway underneath, 20' or higher, makes a world of difference.

[HeliEagle]

Seriously agree.

lovely photos