Category A Takeoff: Background

[ShyTorque]

Nick did not win the Barnes Wallis Award because of his mere good looks and charm...(sounds of coughing heard)!

Please, let's have no comparisons to the bouncing bomb...

there must be some known cases of this proceedure working? Shirley?

AnFI, it certainly works every time I do my check ride, when the examiner fails one of the engines....

[SASless]

Do you do your Air Tests at 95% of MAUW per the charts.....or do you do the Check in a nearly empty aircraft?

[John Eacott]

A few Rotorheads have been in touch asking for a copy of the old 212 Cat A Supplement. I've scanned it in three parts to keep the file size down, you can download them from here:

Part One

Part Two

Part Three

Please note, this is a scan of an old supplement which may have been superseded and may even be discontinued.

Not for operational use!

Each file is about 6mb, and there is a blue 'Download document' above the file reference.

[Savoia]

John: This is interesting, thanks for scanning and posting!

[albatross]

To the best of my recollection the 212 was never re certified using the 3b engines. Does anyone know if it ever was. Performance would be much better I think.
I no longer fly the 212. Just curious.

[AnFI]

No cases known?

Are there really no known cases working or occuring in anger? (Helipad TDP*0.5 or greater)

[TiPwEiGhT]

If you fly the S-92 then it was put in the last RFM update earlier this year. Unfortunately I am unable to send you it.

TiP

[chopjock]

Well I think these Cat A type departures are not as safe as they could be. There is too much reliance on the tail rotor. They have two engines and only one tail rotor, so should base the technique on risking the engines more than the tail rotor by climbing forwards and into translation lift sooner, instead of loading the tail rotor more and for longer than necessary by climbing backwards...

[FloaterNorthWest]

Chopjock,

If you climb forward you enter the avoid curve so if you lose one of the two engines you will crash. So it’s Catch 22.

FNW

[chopjock]

If you climb forward you enter the avoid curve so if you lose one of the two engines you will crash. So it’s Catch 22.

But you would have less exposure time and engines are very reliable... Cat A are supposed to fly on one anyway?

[FloaterNorthWest]

CAT A procedures are designed to keep you out of the avoid curve. If you are in it then you can’t guarantee a safe landing.

Tail rotors are statistically reliable too!

[John Eacott]

Originally Posted by chopjock

Well I think these Cat A type departures are not as safe as they could be. There is too much reliance on the tail rotor. They have two engines and only one tail rotor, so should base the technique on risking the engines more than the tail rotor by climbing forwards and into translation lift sooner, instead of loading the tail rotor more and for longer than necessary by climbing backwards...

You have an never failing ability to misunderstand procedures: and make absurd comments. Under your 'risk' analysis you have seemingly ignored one main rotor system in most helicopters let alone one MGB, one cyclic, etc etc. The Performance departure profiles are well developed and long standing, but nothing in aviation will allow for all and every possible failure: it's a best risk/failure outcome.

That sort of post is what gets traction with media researching this thread for shock/horror headlines without either understanding nor follow up research.

[nigelh]

Floater .... I don’t understand how slowly reversing can be less in the avoid curve than pulling vertically and transitioning to SE climb away ASAP ? Surely every knot of forwards speed you get takes you closer to getting out of the avoid ?? ( and in the same logic reversing would make the normal avoid larger , ie higher than a normal hover as it will take valuable seconds and feet to arrest the backwards speed before initiating a nose down attitude to pick up speed ??) I am not saying you are wrong, but to my mind I would feel happier getting to the speed I could at least maintain altitude as soon as possible . I also think that logically the time it would take to drop the nose and pick up some speed would double if you were going backwards with nose up rather than a flat hover ?
I think I must be misunderstanding something ....maybe the powers that be consider the downside of reversing ( which there really must be ) are worth taking for the upside (??) of being able to see your take off spot during the climb .... ??

Old Fat One ..I think some people on here think that for you to post a theory of what you think may have happened...you should have at the very least a proper understanding and almost certainly be an experienced, probably professional, pilot . I tend to agree . My comments are a genuine question regarding the effectiveness of Cat A type take offs and are probably therefore thread drift . Apologies .

[helicrazi]

Originally Posted by nigelh

Floater .... I don’t understand how slowly reversing can be less in the avoid curve than pulling vertically and transitioning to SE climb away ASAP ? Surely every knot of forwards speed you get takes you closer to getting out of the avoid ?? ( and in the same logic reversing would make the normal avoid larger , ie higher than a normal hover as it will take valuable seconds and feet to arrest the backwards speed before initiating a nose down attitude to pick up speed ??) I am not saying you are wrong, but to my mind I would feel happier getting to the speed I could at least maintain altitude as soon as possible . I also think that logically the time it would take to drop the nose and pick up some speed would double if you were going backwards with nose up rather than a flat hover ?
I think I must be misunderstanding something ....maybe the powers that be consider the downside of reversing ( which there really must be ) are worth taking for the upside (??) of being able to see your take off spot during the climb .... ??

so in this scenario in a stadium, how do you prpose to depart whilst maintaining a safe landing area? if you elected to transition forward without the reverse, before tdp you need a reject oei, that might take you into the seating area. After tdp oei you won't have the climb performance to clear the roof.

the profile flown gives you a safe landing area before oei before tdp, you drift down to where you started, oei after tdp you have sifficient height to transition and clear the roof

[212man]

Originally Posted by nigelh

Floater .... I don’t understand how slowly reversing can be less in the avoid curve than pulling vertically and transitioning to SE climb away ASAP ? Surely every knot of forwards speed you get takes you closer to getting out of the avoid ?? ( and in the same logic reversing would make the normal avoid larger , ie higher than a normal hover as it will take valuable seconds and feet to arrest the backwards speed before initiating a nose down attitude to pick up speed ??) I am not saying you are wrong, but to my mind I would feel happier getting to the speed I could at least maintain altitude as soon as possible . I also think that logically the time it would take to drop the nose and pick up some speed would double if you were going backwards with nose up rather than a flat hover ?
I think I must be misunderstanding something ....maybe the powers that be consider the downside of reversing ( which there really must be ) are worth taking for the upside (??) of being able to see your take off spot during the climb .... ??

Old Fat One ..I think some people on here think that for you to post a theory of what you think may have happened...you should have at the very least a proper understanding and almost certainly be an experienced, probably professional, pilot . I tend to agree . My comments are a genuine question regarding the effectiveness of Cat A type take offs and are probably therefore thread drift . Apologies .

Oh great - let’s have another HV curve thread. I guess we’ve only had about 10 or so in the last decade. A Cat A take off profile does not put you in the HV curve. It may appear to but the WAT graphs and profile/technique obviate it. The HV curve is a very blunt certification instrument that does not recognise Cat A profiles and is based on extremes of mass, C of G and density altitude. Kick it out of this conversation!

[nigelh]

So if you have gained , as in this case , a maximum of 20-30m by reversing ... you are at say 30-40m height . How much airspeed will you have available to settle back to the same spot ? Enough to be in transition ? I wouid say no . Enough to eliminate possible vortex again no . So what really are you gaining ? You could eliminate all the risks we have discussed in exchange for having to come down admittedly more vertically?
maybe not a point but in the 109 I would rather do vertical because when near transition speed she shakes and rattles like hell !

212 .. just seen your message . Fair enough !!

[Slowclimb]

Isn't the idea that, if you lose an engine, you fly down the path you just went up to that nice safe landing spot you were sitting on a few seconds ago?

[212man]

Originally Posted by Slowclimb

Isn't the idea that, if you lose an engine, you fly down the path you just went up to that nice safe landing spot you were sitting on a few seconds ago?

Yes - if you lose an engine. Do you think this is what happened? If not, what’s the relevance of your question?

[chopjock]

helicrazi

the profile flown gives you a safe landing area before oei before tdp, you drift down to where you started, oei after tdp you have sifficient height to transition and clear the roof

And this takes more than twice as long, exposing the aircraft to a kind of "tail rotor avoid curve". I cringe every time I see this type of departure thinking "I hope that tail rotor doesn't let go, why is it taking so long"...

[HeliComparator]

Originally Posted by nigelh

So if you have gained , as in this case , a maximum of 20-30m by reversing ... you are at say 30-40m height . How much airspeed will you have available to settle back to the same spot ? Enough to be in transition ? I wouid say no . Enough to eliminate possible vortex again no . So what really are you gaining ? You could eliminate all the risks we have discussed in exchange for having to come down admittedly more vertically?
maybe not a point but in the 109 I would rather do vertical because when near transition speed she shakes and rattles like hell !

212 .. just seen your message . Fair enough !!

it really doesn’t matter what you think about the profile, nor what anyone else on here thinks about it. The important point is that it is the flight manual procedure, certified following extensive testing by company test pilots.

I flew the AS33L2. It had a backing-up Cat A helipad procedure. I also flew the EC225, it had a vertical Cat A helipad procedure. Both procedures were entirely valid. The backing-up one gives better view of the reject area but you are backing up into unseen territory and overdoing the backing up results in too much rearwards speed. The vertical one is easier provided you can keep the landing area in view. As a TRE/TRI I did more OEI rejects from just before TDP than I care to remember. What a surprise - none of them had any hint of vortex ring!