TO perf

[ppppilot]

Hi friends.
Which are the major companies’ procedures to determine the large planes PTOW?
I suppose the payload limit for that flight, acft, conditions, SID and LDGW, is given by the flight ops dispatcher to the PIC. But if conditions changes before taxi. How do you check you are ok with the max PTOW?
Everybody has a rwy analysis chart to check performances. But as far as I know that chart only takes into consideration, obstacles until the final segment of the one engine failure path. It doesn’t on all engine running SID obstacles. There are SIDs very exigent on performances. Do you have charts for each SID? Do you need to check obstacles in the performance chapter of the OM? Are you comfortable enough with the fms calculations?
Thank you in advance.
Tailwinds.

[Pugilistic Animus]

There should be notation on the SID if higher than the standard 200ft/nm gradient is needed---Or on TERPS charts the procedure will have the notation (Obstacle) so that it may be visually claered,
so you just see if your at a WAT combo that ensures you meet the required ODP or SID gradients

[Pugilistic Animus]

oh---what is a PTOW?

[ppppilot]

Thank you PA.
PTOW states for Performance Take off Weight. It is the max TOW due to perf limitations.
You have described how to know if a SID requires special calculations.
I will give you an example of what I want to know.
You are PIC of a 744 and at your arrival to OPS your company tells you are to TO rwy10 using XXX1A SID. That SID requires a 5% gradient for the 2nd segment. Your OPS agent gives you a performance analysis showing that you may accept only 380 of the 400 pax already checked, plus 20 tons of cargo, plus the fuel needed for the flight. That max weight is your PTOW. Therefore you are limited by performance due to obstacles at the 2 segment for the rwy 10.
When you arrive to cockpit, the ATIS has changed and the active is the 28. The dispatcher wants to begin the boarding but the SID XXX1B used for the rwy 28 requires a gradient of 8% for the 2nd segment.
There goes my question. How can you tell to that anxious dispatcher how many pax do you accept? Were do the MAIN COMPANIES search for the new PTOW? Do they use special charts? Will you introduce the TOW into the FMS and checks if it is OK with the obstacles? Or, Will you make your own analysis at the performance charts of the OM?
What is a WAT combo?
Tailwinds

[Slasher]

All that is usualy covered in the individual runway TO charts
provided by the Co (at least the ones Ive worked for).

So if rwy 28 dictates a much lower TOW than rwy 10
- check if rwy 10 gives a better weight with the present
dw comp (might only be a few kts). If it does then ask
ATC for rnw 10 due op requirement
- if its rnw 28 hands down then get the best TOW taking
into acount flap, HW comp, EO proc, etc.

With this rnw 28 weight
- if payload critical then calculate a diversion point (thru
Ops) from a suitable enroute airport. This will lower your
variable reserve and increase payload. This assumes you
havent finished refueling. If you have, then....
- If fuel critical (or is already onboard and no defueling)
calculate your new payload.

[ppppilot]

Thank you very much Slasher. That is very kind of you.
I must say a couple of things.
I am not talking about single engine procedures. Only about how much weight can you accept to clear the obstacles in an all engines running SID.
You said that your rwy analysis covers all the obstacles for that rwy. But I am not sure of that.
I use to fly with the best runway analysis software. I have also worked with Flygprestanda charts. If you go to their web you will see that obstacles to analyze are optional to the companies. Sorry for my English. I explain it better. Flygprestanda gives you a solution just in case of an engine failure only up to the diversion point, of the scape path that they suggest for that rwy and the current SID you are flying. Further analyses on the obstacles along the particular SIDs up to the TO final segment with all the engines running are optional to the costumer.
In fact, probably you have noticed, that you only have one rwy analysis chart on each rwy, not on each SID. If different gradient SIDs would be covered in only one chart, the company would be loosing cargo load potential on the less gradient SID.
May be that you have been using, several rwy analysis charts for the same rwy, grouped into same performance requirements. If that is not the case. How do you make your weight calculations to comply with those requirements?
Thank you again.
Tailwinds

[EMIT]

Note that T/O performance with one engine less, is less than with all engines running.

Performance calculations are only performed up to 1.500 ft Height (above take-off runway). If there is a performance problem, that is, if obstacle clearance is not guaranteed in any direction, then a specific engine-out departure procedure will be developed (by the operator).
If you get an engine failure after the point where the engine out procedure splits off from the ATC SID, first of all note that you are then already at an altitude that belongs to all engine performance up to that point, so greatly above any near obstacle problems. Secondly, now it is up to the captain to determine the safest course of action. Usually this will involve not to continue in the direction that requires the high climb ratio's that you are referring to.

To recap: performance calculations are per runway, not per SID. The performance will be safe omnidirectionally (so, usable for all SID's). If there is a problem in any direction, then a specific engine out procedure will be provided. Obstacles that are distant, like a mountain range at 30 nautical miles from the aerodrome, usually fall outside the scope of take-off performance calculations - they will have to be adressed via the common sense of the flight crew.

[Vsplat]

Good afternoon all.

The subject of all engine climb has not been covered all that well by manufacturers, regulators, or operators. We tend to focus on the engine out case because it is a certification requirement and our regulators demand it. There is a long standing belief that climbing safely away on one is a guarantee of SID compliance. Not true.

First off, we need to separate the apples from the oranges. The criteria for dealing with an engine failure are based on net takeoff fight path, 35 feet (dry runway) vertical separation and as little as 300 feet (or a splay, depending on where you are) laterally. This is also flown at relatively low speeds and the acceleration height is raised as required to ensure clearance (to a point of course).

Compare this to the standard instrument departure design. Basic obstacle identification surface, (152'nm) even over flat terrain, increased by 48 feet per nautical mile, all the way up to minimum enroute/safe altitudes (terms vary by document). Lateral splay is much, much wider than used for the engine out procedure. Aircraft flying a SID are operating at higher speeds and may accelerate relatively low, depending on noise abatement or other SOPs. Accelerating early is encouraged for fuel burn, but the lower you do it, the flatter the line from the departure end of the runway through the point you are climbing enroute.

Of course, further dividing the issue is the fact that an operator may have a specific engine out route established for a runway end. If this differs from the SID routing, does the operator conduct a separate analysis for the normal departure? None that I have worked with do.

Consider that more and more SIDs have high gradients not tied to terrain (ridiculously so, the last time I saw FRA at over 700'/nm). An engine out analysis based on terrain clearance may put you well below the SID. Consider three and four engine aircraft that may be more limited by the all engine takeoff distance than the engine out to 35 foot case, and you can start to see the delta. I have done some analyses of these cases and found all engine performance as much as 300'/nm too low for the SID. Yet pilots accept the clearance as they lack the information to do otherwise.

All this to say, you raised an excellent question here, but it is Pandora's box as the data to fully comply is simply not there for many aircraft types. Most operators would take a payload hit if truth were known, so don't look for this to get regulated any better.

Cheers
Vs

[john_tullamarine]

.. I find this thread a tad disturbing ... if you are flying a SID AEO, then you MUST have a gameplan to cover the very much inferior OEI climb performance .. whether that involves continuing on the SID, or heading off along some escape path ..

.. some here appear to be separating the two .. as if you have an option as to when you will, or won't, have a failure .. ?

The question of AEO climb is covered by the presumption that the aircraft will be flown in a manner which will cause it to be above the OEI flight path along the same track .. but if you haven't done the OEI sums up front, then don't have a failure half way down the takeoff path ..

[Vsplat]

John, it's all about payload. The point at which an operator MUST account for an engine failure is at Vef. From that point, either the accel-stop must work, or the accel-go must work. In most jurisdictions I'm familiar with, the requirement to absorb an engine failure part way through a normal departure is grey to say the least.

Most special special engine out routings include a point of deviation from the normal operations SID. There are not infinite points of egress from the SID routing to the engine-out one. While we often believe that the point where the two routes split is the point at which an engine failure can be handled on the SID routing, there often is nothing to shore up that belief.

But this question was regarding a simple, normal takeoff. Do you know you can meet the published gradient with all engines operating? The answer is, unless you have specifically looked at your all engine performance beyond the altitude specified in the SID, you don't know. The criteria for one engine inoperative takeoff are not linked in any way to the SID design.

Muddy enough?

Cheers
Vs

[john_tullamarine]

..we are in heated agreement, my good friend ..

In most jurisdictions I'm familiar with ..

Precisely .. and isn't it stupid ? Why not just accept that you aren't going to have one cease to rotate and get on with the task of making money ? One could save a few dollars on all those unused OEI takeoff charts ...

Do you know you can meet the published gradient with all engines operating

One should have, at the least, some generalised takeoff data in the ops manual which provides explicit AEO gradient capability data. Not too much of an ask to have that data in one's shirt pocket cheat sheet notebook ..

The criteria for one engine inoperative takeoff are not linked in any way to the SID design

You (obviously) know that .. we see one of our tasks as getting the message across to many others who (quite obviously) don't ...

[mutt]

Extremely muddy waters made even muddier depending on the regulations that one operates under :):)

I use to fly with the best runway analysis softwareI'm curious, what software do you consider the best?

J_T, I would estimate that we account for SID's in approximately 0% of our produced data. The concept being that the takeoff is straight ahead in the event of an engine failure, if the straight out path doesnt deliver sufficient payload, then an engine out turn procedure is developed. All of this is based upon obstacle data and not SID requirements. For the SID, the crew is on their own.

Mutt

[john_tullamarine]

For the SID, the crew is on their own

I have no problem .. so long as the crew knows that ... then it is a case of who will refuse the SID and follow the OEI track .. thereby inviting an invite for tea and bikkies .. hold the tea and bikkies ....


takeoff is straight ahead in the event of an engine failure

just a small problem if the failure delays itself until after the first SID turn ...


Sometimes I'm glad I'm not flying these days ...

[ppppilot]

Thank you all.
Vsplat. Quote
The subject of all engine climb has not been covered all that well by manufacturers, regulators, or operators.
Straight in the center of the target.
My opinion is that airplane manufacturers have abandoned the responsibility to operators and operators to pilots. And we pilots are not aware enough on that.
An 8% climb gradient is not a factor for light to medium aircrafts AEO. So that is one reason to be difficult to understand my question. I have always talked about heavy airplanes, more subject on the question.
Please. don't talk about OEI nor EOP.
I say again my question:
How do you know that you comply clearing the obstacles on a SID AEO with the MTOW?
I query other way:
How can you determine your performance TOW for a given obstacle at the SID?
The rwy analysis it is not enough. There are more climb exigencies on some SIDs. LEMD is an example. The minimum gradient taking off to the North is 5,5%. I haven’t found too much in the B757 or A340 OM. Only in the certification performances chapter of the A340. The more close chart to that question is 4.01.40 “Distant obstacles at TO”. That chart covers obstacles up to 5000’ height and up to 46000 meters distant from the end of the rwy. The chart considers only a maximum of 6% climb gradient. As far as I know, certification performances are operative limits. Therefore I am not legally allowed TO from most of those SIDs.
However I have seen B744 and A346 of the main companies accepting those SIDs and those planes are more restrictive than A343 on the 2nd segment because of the high flap setting they use.
On the other hand I know a little about FAR and JAR on EOP for the TO but none on AEO.
Then I am questioning... What have I missed to take into consideration? What procedures are using the most of the companies? Can anybody help me to get out of my error?
Thanks Vsplat for giving me a clue and thanks to all for your help. I agree to all the words you said.
Tailwinds

[ppppilot]

Hello Vsplat.
I have been rereading your post.
As you said, there is a proliferation of exigent SID, mainly because of noise abatement. What I see there is that the number of exigent SID because of obstacle clearance is also growing up, but not at the same rate that new airplane models improve their performances. I would say better, “TO performances are decreasing on new models, in the name of costs and fuel savings, while SID’s climb requirements are increasing”. And we pilots are performing blind TOs.
Reducing the number of engines of the airplanes, thus reducing the power and increasing the risk on extended over water operations, to save costs. Increasing the precision requirements on altitude and vnav, to increase the traffic potential. Going to the limits with the TOW, thanks to better soft and hardware in use today.
I agree we are getting better in technique and that is good for all of us. But the balance field is clearly falling to the money side, against safety and there, passengers and pilots are loosing. Long time ago, flying was a public service. Today the trend is to become a mountain of numbers.
I believe neither impossible nor too expensive, to have rules and systems to determine the TOW more precisely and safely as we have discussed in an earlier post
http://www.pprune.org/forums/showthread.php?t=315101 (http://www.pprune.org/forums/showthread.php?t=315101)
I am only asking to increase the safety at the same speed that precision does. Thanks to pprune we can discuss on that.
Tailwinds

[Vsplat]

ppppilot, I think you've lost me.

I don't believe this is an issue of increasing aircraft technology vice obstacles. My post was intended to differentiate between those aspects of intial climb that are analysed (one engine inop) and those that typically are not (all engines operating).

I do not, in fact, see this as primarily an obstacle issue at all. Indeed, the worst case scenarios of non-compliance with SID gradients occur with that gradient is established for non-obstacle reasons, such as noise, military area avoidance or inbound traffic routing. In these cases, the performance engineer will reference obstacle data for the engine out case, finding a relatively shallow, safe path, while not dealing with an extreme all engine climb requirement.

I hope this clarifies a bit.

Vs

[mutt]

I believe neither impossible nor too expensive, to have rules and systems to determine the TOW more precisely and safely as we have discussed in an earlier postI might have missed it, but would you kindly explain how you think its safer?

Your Jeppesen charts has a table for gradient, speed & rate of climb, surely from experience you should know the approximate rate of climb on your aircraft with all engines, cant you compare this to the SID?

Mutt

[ppppilot]

Dear Vsplat.
Long time ago, I was in Montreal getting the CRJ200 type rate at CAE. It was the paradise for a pilot. Asking questions directly to the engineers designers of the plane, and studying with the best material and instructors. Nice place Canada, modern and open minded. A little bit freezing to what I am used.
Regarding to your post. You have described where I wanted to arrive, better than me.
I quote:
The subject of all engine climb has not been covered all that well by manufacturers, regulators, or operators. We tend to focus on the engine out case because it is a certification requirement and our regulators demand it. There is a long standing belief that climbing safely away on one is a guarantee of SID compliance. Not true.
And from another thread:
http://www.pprune.org/forums/showthread.php?t=317024 (http://www.pprune.org/forums/showthread.php?t=317024)
There is a common belief that analysing a departure for the one engine inoperative case guarantees SID climb gradient compliance. Not actually true.

The rest of my words, are only the modest opinion of a simple pilot not derived from your posts.
Resuming my feelings. The payload for normal take offs, should be better controlled. In my modest opinion, actually it is neither well determined nor measured.
What I am trying to learn here from all of our colleges is, if we are aware enough on that and if we could be accepting SIDs that doesn’t comply with performance certifications, as Vsplat said, because of a lack of information.
I have three doubts on the question.
First place. Where do an AEO TO ends? It is not at the moment having achieved speed and configuration to climb to cruise FL? It could be as high as 18000ft. Like those Rocca2N, Rocca2P and Rocca2Q for rwy05 at LSGG, requiring a 5,4% gradient up to that altitude. But usually. It is 250knots to maintain up to 10000ft… or whatever other speed calculated for the FMS after that last restriction?
Second place, I would like to know which are the maximum climb gradients for the A346, B744, B777, A380 and A330 at MTOW AEO up to that final segment of the TO. Any information on that? Any link? Mutt, you must know a lot on it. Please help.
Third place, I would like to know if those gradients are charted in the OM, as the one that I have described for the A343 OM and if there is any operational procedure in the main companies to check that, on every TO.
Thanks to all again.

[Pugilistic Animus]

Tallyho!, to all and Pppilot,

I was eagerly awaiting the evolution of this thread but class had begun then I had to leave for a personal trip to FRG- RDU-ATL so I spent the weekend, in a clapped out Seneca,only Stormscope and an old GPS, in solid IMC--- killer turbulence two diversions--with 3 horrified friends and one nervous pilot:eek:.

So, I haven't had time to reply...I've thoroughly read all of the replies and I just have a few pedagogical comments that I've repeated a million times in class, concerning DPs and gradients....now, I have not worked for "most major airlines", but the 135 operations with which I've been involved, all absolutely required that the AEO Departure path was looked after.., by the pilot---the limiting weight and speeds for the OEI TODR and flight path already having been done---here's an outline assuming the most primitive and basic of operations---because different types/AFMs/ companies--all do it in the same fundamental manner.

There are two basic documents required or can be used.
1. the AFM--- Departure Climb Gradients, all engines operating---but beware the charts will only cover from the gear up point, but the gradients [if nonstandard] that have to be maintained above the obstacle clearance surface [OCS] that begins at the DER and a properly planned TO [i.e OEI performance] will have a 15% distance margin---that will allow an aircraft to meet the AEO perf. segments anyways.
2. the actual procedure will have a table in the TPP that has a climb gradient chart if TAS is computed and the required gradient is known the the ROC for a given gradient are then shown [don't be too precise here], this will serve as a double check
---you should find that the AEO segments will rarely if ever be found to limit TOW, but they can and will at times---so don't skip this when higher than standard gradients are required!


Some comments on SIDS and ODPs there are three conditions all previouosly mentioned above by others---

1. A higher than normal gradients has been established for environmental reasons, noise abatements and such---as previously stated---so the few moments of computation allows the ground people to consider pilots to be friendly neighbors:8

2. Limiting obstacles aways out from the DER which affect the OCS sometimes require that a higher than standard gradient, because the gradient required to over the OCS had to account for some limiting obstacle. meaning a 48 '/nm climb has to be maintained over the OCS...
---SO, if the OCS surface is already at a gradient of say 200'/nm then in order to clear it, legally, one needs a 400'/nm climb gradient.---so here AEO performance may take on a more serious meaning!

3. the last case is a little special ---and is due to specifically Low Close-In Obstacles
because such a scenario would mean that a very high climb gradient would have to be guaranteed but would be unnecessary later down the line, so Obstacle Departures are published and are annotated with the word [Obstacle] the textual description gives pilots the location and height of the obstacle and allows for Visual clearance of the obstacle. but climb gradients are also established---or if not clearly stated you may assume standard conditions--

I understand your frustration, because the EFATO case is so thoroughly considered [and rightly so!] as it is usually more critical--very little considers the possibility of the AEO flight path---not just the net flight path---

I hope I've helped a bit


PA

[mutt]

1. the AFM--- Departure Climb Gradients, all engines operatingI have never seen an AFM with ALL ENGINE OPERATING data.

will have a 15% distance margin---that will allow an aircraft to meet the AEO perf. segments anyways.Can you give me a reference for the 15% value.

TPPWhat is this?


Mutt

[Pugilistic Animus]

Hello Mutt,

Regarding the AEO I actually have three AFMs with such data[I can't remember which type is which but I'll confirm them for you as they are not in my presence ---only one of them of them is a 'big jet' though IIRC

hence only m reference to the use of a cross checking in case no such item is available

I was referring the Liftoff point AEO within then TORR

TPP= Terminal Procedures Publication [govt charts]

PA

[PURPLE PITOT]

Hi, can anyone direct me to the source document for regulations applying to JAA 25 aircraft for one engine inoperative climb gradient planning, and the construction, approval, and use of emergency turns.
Thanks

[mutt]

Have a look at the Airbus getting to grips with aircraft performance... I think that its in there!

Mutt

[Nigel Croker]

Thanks. Anyone got a link to this, the one in the index does not work.

[mutt]

SmartCockpit - Airline training guides, Aviation, Operations, Safety (http://www.smartcockpit.com/pdf/flightops/aerodynamics/18)

Mutt

[bflyer]

HI....google this

It's a CASA document CAAP 235-4(0)
called ( guidelines for the consideration and design of engine out SID EOSID and engine out missed approach procedures )

It's not JAR but it has been very helpful to me
Regards
bf

[PURPLE PITOT]

Brilliant, thanks.