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Category A Takeoff: Background

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Category A Takeoff: Background

Old 29th Nov 2013, 10:55
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Category A Takeoff: Background

Is anyone aware of the history behind the development of the Category A Takeoff. Where it was first developed, who were the development pilots or any information about its origins?



From an operational point-of-view, has anyone encountered any 'challenges' while performing this manoeuvre?

Is there, for example, any collision risk while conducting CAT A departures (especially off-airport) as a result of the restricted rearward field of view?
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Old 29th Nov 2013, 11:33
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Is that a comedy profile? Spot the deliberate mistake..............
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Old 29th Nov 2013, 11:36
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Not intentionally, no. T'was the only illustration I could put my finger on.
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Old 29th Nov 2013, 12:07
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TDP = Takeoff decision point.

LDP = Landing decision point.

Is there, for example, any collision risk while conducting CAT A departures (especially off-airport) as a result of the restricted rearward field of view?
If you are a bit slow taking off from EGLW, someone might put up another crane right behind you.....
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Old 29th Nov 2013, 12:10
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I know that the screen height of 35 feet was based on a double decker bus (at Croydon)

Phil
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Old 29th Nov 2013, 12:16
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Sav,

One would assume that you would have taken a look at the departure/takeoff path beforehand?

FM Supplement -

NOTE The helipad maneuvering area and takeoff flight path shall be clear of obstacles.
And all reference to LDP in your pic should be TDP?
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Old 29th Nov 2013, 12:28
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Was there Life before Cat A?
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Old 29th Nov 2013, 14:06
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SASless, Yes, it was called taking off and going flying. Many moons ago (30years) during my initial S-76A training, Cat A was explained as a selling point since the S-76A was certified for Cat A operations. The RFM included all of the appropriate charts. A close look at the charts revealed that, to meet Cat A requirements at gross weight, one would need an unobstructed helipad about 1500 ft in diameter. That is just what we had at Stratford.
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Old 29th Nov 2013, 14:36
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RV: Agreed.

However, in addition to fixed obstacles I was wondering too about the hypothetical risk in making a rearward vertical takeoff and the potential for climbing into overflying traffic; for example in a rural location on the periphery of a control zone etc.

My main interest however is in learning (if possible) 'when and who' were involved in developing this procedure.
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Old 29th Nov 2013, 14:54
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I'd be interested to see some stats showing how many lives have been saved by Cat A in helicopters. I know of only one actual engine failure during a takeoff and that wasn't being flown under Cat A because the S76 was not capable in the conditions required by the operation. The aircraft was safely landed.
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Old 29th Nov 2013, 16:21
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one would need an unobstructed helipad about 1500 ft in diameter
Then you would have used a DHC6 Twin Otter because it could lift more out of the same space!
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Old 29th Nov 2013, 16:38
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Then you would have used a DHC6 Twin Otter because it could lift more out of the same space!
Far cheaper too!

When Shell Oil (Nigeria) went from Bell 212's to the EC-155....the Heliports became runways....that should tell you something about the effects of using Cat A profiles and performance.

I have practiced the "Reverse" Takeoff Profile....never ever did one for real in daily operations.

Also did some very convoluted gyrations in other aircraft that were supposed to provide for Cat A performance (with a very limited weight allowed) as well....but in the end would have been far happier just flying the machine like a helicopter it was.

I was never on a Civliian operation where an engine failure on Takeoff ever occurred....not that they do not.....just they never did anywhere I was based.
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Old 29th Nov 2013, 19:41
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The helipad Cat A was around in the mid/late 70s and became part of British Airways procedures offshore on the Brent platforms with their large unobstructed decks (Brent B in particular). The diagram in the OP is not very representative as most profiles are far more vertical than is shown: the criteria is to keep the helipad visual through the chin window, not out of the front screen! We dabbled with the idea in BEAS 212s, but with rig shuttles and 5 minute turnarounds it wasn't deemed practical plus many of our into wind profiles didn't allow a back up.

The BA S61 drivers (when introduced to the procedure about 1977 or 78) actually started using it off the runway at Sumburgh, which seemed a strange thing to do with thousands of feet of reject area ahead on departure.

I've found the biggest challenge to be getting pilots to understand the overall concept along with judging the TDP properly. Once that hurdle is overcome then there is no real issue in carrying out the procedure.
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Old 29th Nov 2013, 19:48
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Hi Savoia

I believe that the rearward take off profile was produced to allow the mirror newspaper group to fly the printing plates from the rooftop helipad at their London office to the printing presses in Manchester. It's quite possible that I am talking bolloxs though!

Cheers

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Old 29th Nov 2013, 19:56
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Originally Posted by TeeS View Post
It's quite possible that I am talking bolloxs though
Tees, more than possible

The FAA produced a paper in 1991, Helicopter Rejected Airspace Takeoff Airspace Requirements which seems to be addressing the problems of too-steep departure paths and a more flexible airspace system to allow for this. Prior to this report, the helicopter manufacturers were following the fixed wing criteria laid down by the FAA (IIRC).
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Old 29th Nov 2013, 20:28
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Originally Posted by TeeS View Post

Hi Savoia

I believe that the rearward take off profile was produced to allow the mirror newspaper group to fly the printing plates from the rooftop helipad at their London office to the printing presses in Manchester. It's quite possible that I am talking bolloxs though!
This is precisely what I remember (well done TeeS ) but .. I didn't trust myself to bet that this was in fact the genesis of what would become the 'CAT A' departure profile.

Does anyone recall who Maxwell's driver was at the time, we are talking mid-to-late 80's?

Originally Posted by Savoia View Post

AS355F1 G-RMGN atop 'Maxwell House' in 1987 (Photo: Gary Lakin)

Here G-RMGN seen atop the former 'Mirror Group Newpapers' office aka 'Maxwell House' at no. 8 New Fetter Lane.
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Old 29th Nov 2013, 20:45
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Thanks Savoia

Hopefully I'm not entirely senile yet then. It may have been Flight International that had an article about the development of the profile and I would guess that was, as you say, around the mid-late 80's

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Old 29th Nov 2013, 21:01
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We pre-dated the London rooftop departures by 10 years or so with Cat A in the NS.

My copy of the 212 manual with Cat A profiles (including Vertical Takeoff Profile) has the revision dated in September 1976, with the original having been published in August 1972.

Forget the idea of the Mirror being at the forefront of this
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Old 29th Nov 2013, 21:21
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Originally Posted by John Eacott View Post

Forget the idea of the Mirror being at the forefront of this
Fair enough. Had my doubts.

Do you suppose it began with one of the manufacturers?
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Old 29th Nov 2013, 21:54
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Hi John

Thanks to the wonders of the digital World, I have found the article that led me to believe the procedure was developed for the Mirror Group operation. It makes quite interesting reading, if only for the dream of masses of rooftop helipads in central London. I now realise that the article doesn't claim this was the first use of helipad profiles (Worldwide) but you might see where my confusion started. Hopefully this link will work:

1985 | 2964 | Flight Archive

Cheers

TeeS
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