approach climb 2.1% vs MACG 2.5% or greater

[aslan1982]

Can someone explain to me the difference between

Approach climb limited weights (2.1%) and Missed approach climb Gradient weights (2.5% or greater)

Here is what I know

- For Approach climb limited weights
-the aircraft climb capability in go around climb config with 1 engine inop, gear retracted and F15 must meet or exceed 2.1% climb gradient

- For CatII/III MACG limited weights at 2.5% climb gradient must be met(one engine out)

- Also for example at FUERTEVENTURA ILS 01R the MACG = 4.0%, so we must ensure that the landing weight does not exceed the MACG weight at the current conditions i.e Temperature and pressure Altitude . So for this we would use the tables for MACG limited weights for grad 4.0% (one engine out)

-The nominal climb gradient of a missed approach based on ICAO PANS-OPS is 2.5%

- Basically for both, if the weight is limiting i.e. less than max landing weight then this should be put in on the load sheet to determine allowed traffic load.


So which one do we use?

Using FUERTEVENTURA ILS 01R as an example

OAT 40 degrees and airport elevation 50 feet

Approach climb limited weight = 74300kg (based on 2.1%)
4.0% MACG limited weight = 61700kg

Obviously Im gonna use the lowest value, but I'd like to know why there are two types. What are the differences.

Thanks in advance. Its been bugging me all morning trying to figure out the differences

[rudderrudderrat]

Hi aslan,

I believe one of the conditions to be met for Max Landing Weight is the ability to make a (missed) Approach Climb Gradient of minimum 2.1%.

Steeper Approach Climb gradients may be met by reducing the Landing weight, or by using a different Approach Flap setting (giving a less draggy GA Flap selection).

[john_tullamarine]

Simple once you put things into the right paddocks ..

(a) certification climb requirements

These relate to Design Standards requirements (eg FAR25) and impose MINIMUM climb capability to give the pilot some chance of going up when he/she desires - ie a limit on gross weight to make sure the aircraft can climb a little under specified circumstances.

These climb limits usually are referred to as WAT (maximum gross Weight for Altitude and Temperature) limits and ensure (at certification) that the aircraft has a modest climb capability in the takeoff, en-route, approach, and landing configurations.

WAT limits are across the board and have no interest in specific aerodromes or obstacles - they are still air line in the sand limits for the AFM.

(b) operational climb limits

There is a variety of these animals and the SID and missed approach requirements fit in here. Absolutely nothing to do with WAT limits and, near invariably, more restrictive.

[aslan1982]

Thanks for the answers

So John, from what I understand by what you wrote

certification climb requirements are to do with approach climb gradient(2.1%)

operational climb limits are to do with MACG(2.5% and upwards)

In the tables i Have the MACG are much more restrictive as you say but they also are based on temperature and airfield altitude

So I understand what you are saying but am I taking it up wrong?

[Pitch Up Authority]

Hello Aslan 1982,

I fully understand your worries and have had the same. Lucky that JAR-OPS came with an answer.

Approach climb and Landing climb are capability criteria only; they have nothing but absolutely nothing to do with the go-around. A bit the same as the take off second segment. (Still air anyway).

The go-around starts from a configuration and speed that is completely different then the one used for approach climb or landing climb, hence the data of these gradients cannot be used. Before JAR-OPS was implemented we used (for a twin) to refer to the WAT curve for the second segment that was 2,4 % and close to the 2,5 %. All this just to have an idea since nothing else was available.

JAR-OPS recognised this and imposed that, data that actually correspond to reality (configuration andspeed) be used.

I used to work for Emirates Airlines in the 90's and nobody in the training department understood what was really going on they probably still don't. So you are not the only one who raises a legitimate question.

Now the issue is basically not very important unless you consider situations at high and hot airports and the context of a CAT III approach with one engine inoperative. Or situations where an overweight landing has to be considered.


Now the question really is, until what altitude the gradient applies. Is it an average value or not?

[john_tullamarine]

In the tables i Have the MACG are much more restrictive as you say but they also are based on temperature and airfield altitude

.. for the same sort of reason that WAT charts are based on weights, altitudes and OATs - these are the principal things determining climb capability

However, WAT and missed approach climb are two different animals looking at different things .. while being similar in that they are looking at (different) climb requirements


The go-around starts from a configuration and speed that is completely different then the one used for approach climb or landing climb, hence the data of these gradients cannot be used.

I wouldn't go along with that statement - in what way is the missed approach configuration different to the WAT considerations ? The only reason we don't use WAT data for obstacle considerations is that the WAT limiting weight gives a low gradient. There is no reason why one can't use the WAT chart data for a LOWER calculated weight to achieve the obstacle clearance requirement ...

Before JAR-OPS was implemented we used (for a twin) to refer to the WAT curve for the second segment that was 2,4 % and close to the 2,5 %. All this just to have an idea since nothing else was available.

Again, I don't think so. The AFM gives plenty of climb data suitable for massaging into obstacle clearance numbers. An operator has, and always had, the ability to go out and do some flight test data to confirm analysis for whatever might have been desired. JAR-OPS might have codified some extra stuff but there is nothing terribly new in the world ...

I used to work for Emirates Airlines in the 90's and nobody in the training department understood what was really going on they probably still don't.

.. which is why the training folk should have referred the matters to the ops engineering specialists .. just like any other airline. I don't know the folk who do Emirates' work but they surely have an ops engineering section ?

Now the issue is basically not very important

.. and ANY place which has obstacle problems. If you don't get someone to do the sums .. how do you have any idea of whether you might be able to miss the rocky bits ?

Now the question really is, until what altitude the gradient applies. Is it an average value or not?

..depends on what the specific Reg you are looking at says and how one might interpret the words if they are not written reasonably clearly

[aslan1982]

Basically the reasons behind my questions is mainly for pre flight planning in the crew room and also because I like to know the reasoning behind it, instead of just agreeing/accepting it. Id like to be able to explain to someone why it is the way it is rather than just telling them, thats the way it is

So for another example...

lets say I'm flying to Salzburg

So in the crew room I get the weather, expected TOW, Landing weights etc...

So lets say (just for argument sake) the weather in Salzburg is +40 Degrees and wind 160/10 1013 hPA and CAVOK with no change through out the day
Airport Elevation = 1411
My ELW is 60T

So i get some Plates and pick the ILS/DME 16 as most likely approach to be flown

So for RWY 16 it states that

CAT 1 MISSED APCH CLIMB ILS DME RWY 16
GRAD MIM 4.2%

CAT11 MISSED APCH CLIMB
GRAD MIM 5.9%

So its CAVOK so I choose the CAT1

Now for dispatch planning I check my Approach Climb Limited Weight chart and it says (based on B737-800 26k 2.1% One engine out F15)

@40 deg Press Alt 2000 = limiting weight = 69400kg

Then I check my MACG charts (based on B737-800 26k 2.1% One engine out F15)

So for 4.5% (nearest/more limiting to 4.2%)

@40 deg Press alt 2000 - Limiting weight = 55700kg

So I have

ELW = 60T
Approach Climb limit = 69.4T
MACG limit = 55.7t

So obviously Im going to have to reduce my ELW to below 55.7 by some means, be it PAX, BAGS, fuel etc.....to be safe/legal to depart

So is there a legal requirement to check Approach climb gradient limiting weights when I know that all charts are based on 2.5% MACG or greater, which are more limiting?

If so why would I check both?

Is the 2.1% just a figure for certification reasons and the 2.5% for actual operations?

.. for the same sort of reason that WAT charts are based on weights, altitudes and OATs - these are the principal things determining climb capability

However, WAT and missed approach climb are two different animals looking at different things .. while being similar in that they are looking at (different) climb requirements

John, would you mind explaining the different climb requirements or the differences between what WAT and MACG look at.

Thank you all for ur time and help:)

[Pitch Up Authority]

From the top of my head, it has been a while since I went into the details of this matter. As such a closer look to the definitions may change my answer slightly but the philosophy will remain the same.

All performance issues are WAT related nothing special there.

Approach climb: While making the AFM Approach climb tables the constructer is allowed to use speeds up to 1, 4 Vs. This is close to min drag and will give the highest figures. These results are just to show a certain capability and have NO practical use. Dont ask me why a second segment is 2,4; 2,7 or 3,0% it is just the way it is and so in a similar way I do not know why they allowed 1,4 Vs to be used. I refer to Joop Wagemakers for more info.

Go around: If you make a go-around, you start from your approach speed using landing flaps and then retract the flaps to a go-around setting at the same speed. This is not 1, 4 Vs and as such the approach climb tables cannot be used even if they provide the possibility to select another gradient. Unless they also allow the use of different speeds. Some of them do.

But the problem of obstacle clearance remains and the 2,5 % gradient is no guarantee since it is referenced to still air.

I am not aware of any operator that makes an analysis similar to the one for Take Off for the Go-Around. That is to say who publishes max landing weights as function of temp, press altitude and wind to meet obstacle clearance. And if you really want to precise, does also take into account the effect of temperature on errors in the altimeter.

As I said before it is JAR-OPS that introduced the requirement to publish WAT curves that were based on realistic Go-Around speeds and configuration. In the same way, was it JAR-OPS that required accounting for loss of climb gradient during turns at 15 bank (Above this the requirement was already in place). Some things change over time. In the same way that the provision for acceleration segments were removed from the Go-Around segments. Nobody really knows why they did that.

So the speed you are using during the go-around is far from 1,4 Vs, hence the performance data are different. To reduce the gap, some connection was made between the approach flaps and landing flap setting that may be used based on the stall speeds (Factor 1,1) in both configurations. This led for example to the use of flaps 2 and flaps 10 on the 737-200. These settings are normally skipped in normal operation and were only used for certification reasons.

Emirates Airlines: EK had a GMFO that refused to listen to the performance engineer who resigned for that reason and joined Boeing as a performance engineer. Of course did the GMFO not allow the PE to resign, he fired him after he resigned, question of keeping his Ego in the right place. Both of us informed Boeing about their practices in order to get some feedback from them so we could use that to force the GMFO to listen. He refused and was fired himself. That Mr John Tullamarine is a reality and I do not think that has changed a bit. At a certain level in management CRM goes out of the window.

Practical use: Depending on aircraft type, temp and press altitude your app or landing climb limiting weight may be lower that the 2,5 % (go-around limiting weight) relative to the ground (wind included).

It is a bit the same as if you would take off from an extremely long runway facing the sea. You might be able to take off with a very high take off weight and no limitations as far as obstacles are concerned. However the second segment gradient will impose a limit although there is no real practical use obstacle wise. It will however imply that when you convert this gradient into level acceleration you will have a certain performance as a consequence of that gradient. Of course you must use the NETT and not the Gross acceleration.

So in general the Approach and Landing climb gradients are a bit the reverse of the second segment requirements for take off. You could approach an airport with an extremely long runway in an aircraft with powerful brakes imposing no problems for landing, even when landing in overweight. In these instances the approach and landing climb need to be complied with. If the temperature at your destination is below a certain value and you have used anti-ice or encountered icing conditions some big corrections on the limit weight lure around the corner.

Parallel with this, an analysis based on obstacle clearance for the Go-Around needs to be made. The question to be answered here is: do I apply the gradient till the end of the Go-Around or do I use an average value? Again this is very unpractical.

These gradients may prevent you to make an premeditated (N-1) CAT III approach at max landing weight at a high and hot airport even when you have a long runway ahead and a strong headwind.

Regulations: Regulations require an analysis to be made for N-1 during all phases of flight, except for an engine failure during Go-Around or on final. Now since Go-Around flap setting all engines is often the same as the one used for take off, and since the speeds used are close to each other you are a bit in the same situation.

This is the story of an engine failure during an approach where the all engine flap setting is maintained. A real challenge, and a lot of fun for those in the OPS management who have to take the decision.

The recommendation of Boeing was to get out of there, definitely if it was a severe damage. The recommendation of EK was to continue although they did not know why and so they used the approach climb gradient as a reference.

[FlightPathOBN]

Aslan...you are mixing and matching.....the 4.2% is the min all engine, not EO. The obstacle clearance surface is based on 2.5%, with a 1.52% NET...

You must be able to meet these variables to use the procedure and the associated decision altitude.

As an example, even though the 737-700 is, by criteria, Class C, your configuration may push you into Class D, and therefore you must use the proper Class on the chart.

[rudderrudderrat]

the 4.2% is the min all engine, not EO.

Er ... no.

It's the gradient you need to make in order to clear the obstacles from that approach at Salzburg, either with all engines running or engine out. We must consider an engine failure at "the most critical phase of the flight", so it needs to be taken into account.

[john_tullamarine]

(I'm not able to comment on the numbers as I don't have your paperwork.)

So is there a legal requirement to check Approach climb gradient limiting weights when I know that all charts are based on 2.5% MACG or greater, which are more limiting?

Again, one needs to keep in mind what the various checks set out to achieve -

(a) the approach climb WAT limit has to be checked as part of figuring the maximum permissible landing weight for the day. This is a basic part of the aircraft certification and is built into the AFM performance information.

If you don't have any other local constraints - obstacles, runway length, etc., then you finish up with a landing weight which looked only at the basic certification requirements and may well be limited by, say, approach climb WAT limits.

(b) now, in the same sort of way you worked your way down from the structural MLW to the (perhaps lesser) LW limited by approach or landing climb requirements, if there are other local considerations, then you need to continue the iteration until you have examined ALL the relevant possible restrictions on LW. The restriction which gives the LOWEST LW becomes the limiting case for the day and determines the MLW for the day.

In effect, you consider the WAT limiting elements every time as part of the AFM process and you also consider all the other stuff as you work your way through the exercise to tick all the boxes. That which limits you at aerodrome A yesterday need not be that which does so today at aerodrome B.

Is the 2.1% just a figure for certification reasons and the 2.5% for actual operations?

that's probably a reasonable comment. Main thing is that you MUST consider the WAT limit EVERY time but sums relating to obstacle clearance only are relevant if you have obstacles to consider. So, for instance, if you are approaching a runway on the coast with the miss over the sea from near the water's edge, then you probably aren't going to be harassed by obstacles (other than the normal transient considerations built into the aerodrome runway numbers - in this case, ships' masts)

.. the different climb requirements or the differences between what WAT and MACG look at.

The Design Standards (say, FAR 25) requires that the aircraft has a set of capabilities, including climb gradient. In the same way as you run through the runway limit charts to check on TODR, ASDR, etc., to make sure you have a reasonable chance of getting off, up and away close in, you need to check on the climb requirements to make sure you can keep doing the away bit and so on through the flight.

Certification looks at the various phases of flight and requires a climb capability to ensure that the aircraft can stay up (go up ?) rather than necessarily have to come down. For instance, refer to FAR 25.111 and subsequent (http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=062ad2663e961a017ecc5bdb680b40c6&rgn=div5&view=text&node=14:1.0.1.3.11&idno=14#14:1.0.1.3.11.2.155.13) which talk about climb matters (amongst other things)

The aircraft, as certificated, is deemed to be OK to go fly. However, in the real world, there are other things (obstacles, for instance) which might cause the basic certificated aircraft some grief so we have Operational Standards which consider such additional matters.

So, if you look at FAR 121.189 and subsequent (http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=da36a4f4a14709f204a4d6e50b5a16a9&rgn=div5&view=text&node=14:3.0.1.1.5&idno=14#14:3.0.1.1.5.9.2.10) you can get a feel for the operational rules. I am not an FAR specialist so others may chip in with further references appropriate to the discussion. However, this is a suitable place for you to start some reading, I suggest.

Main thing to keep in mind is that the airworthiness (Design Standards) and operational rules are there to give you a reasonable chance of getting from A to B without coming to grief somewhere along the way ...

Rather than have me just rabbit on, perhaps you can put further specific questions and we can have a go at answering them specifically ?

Caveat - the current specific rules may not apply in detail to a specific older certification Type

While making the Approach climb tables

The AFM and associated OEM documents will provide guidance relating to the operational techniques for missed approach. It is reasonable to presume that there will be some degree of consistency in such advice. I didn't think it necessary to belabour the point that the operator is perfectly free to go do some more sums and flight tests to satisfy the operator on any point of concern. The AFM, being concerned with airworthiness issues, will not necessarily be easy for the pilot to use without some competent and relevant PE skills. That's the way things are, I'm afraid ...

I am not aware of any operator that makes an analysis

Many don't, some do. I suggest that any for whom I, Old Smokey, and Mutt have worked .. and others I can bring to mind from the past will have had such considerations looked at. It is not a case of running such analyses for EACH runway .. but, certainly, it is good corporate governance for risk management of the nasty ones ...

was it JAR-OPS that required to account for loss of climb gradient during turns.

I suggest that turn loss accounting predates the EASA folk by many decades. It has been a requirement for as long as I can recall to address gradient loss for other than insignificant heading changes. The usual AFM, for takeoff, will contain a chart providing such decrement data. The same sort of philosophy is just as relevant to missed approach escape matters.

One needs to keep in mind that the Rulebook sets a minimum standard only. Sensible corporate risk management, in many cases, ought to dictate additional conservatism in various areas ....

That Mr John Tullamarine is a reality

I can't speak to your specific operator and experience but, certainly, I have observed some in the past which have done things I wouldn't condone. Also, if I have got up your nose a tad, that wasn't my intention and, for that, my apologies ... ?

[Pitch Up Authority]

No problem John,

This forum is a nice place to address these issues. It is only a pity that these things are not properly addressed during ground school when preparing for the ATPL.

Cheers

PUA

[9.G]

aslan,
4.2. Go-Around Requirements
4.2.1. Normal Approach
During dispatch, only the approach climb gradient needs to be checked, as this is the limiting one. The minimum required gradient is the one defined during aircraft certification (Approach Climb). Operators have a choice of go-around speed (from 1.23 VS1g to 1.41 VS1g), and configuration (3 or 2) to determine the Maximum weight limited by go-around gradient. In the rare case of a go-around limitation during dispatch, operators can select CONF 2 and 1.4 VS1g for go-around calculation, and should no longer be limited. Nevertheless, even if the regulation authorizes such assumptions, it is important to warn pilots about the speed and configuration retained, as soon as they are not standard (CONF 3 and 1.23 VS1g). In a normal approach, the required climb gradient is 2.1% for twin and 2.7% for four engine aircraft, independently of airport configuration and obstacles. During dispatch, operators can account for the gradient published in the airport approach chart. :ok:

[HazelNuts39]

Is the 2.1% just a figure for certification reasons and the 2.5% for actual operations?

For an airplane certificated under European airworthiness rules (JAR-AWO), 2.5 % is a certification WAT limit that applies regardless of obstacles for dispatch to an airport with a forecast of CAT II conditions. It is more restrictive than the 2.1 % that applies for CAT I because of the increased probability of go-around in CAT II conditions.

Regards,
HN39

[john_tullamarine]

It is only a pity that these things are not properly addressed during ground school when preparing for the ATPL.

Ain't that the truth ...

I have seen the endorsement programmes vary from excellent to abysmal.

As a pilot, I was fortunate to have been exposed to the old AN (TAA and QF) systems in an earlier life and the folks running those shows were motivated to provide pilots with a lot of nice to know data. Wal Stack's QF notes, especially, are still quite highly prized for their reference value. John Walsh, Roger G and their successors at AN, and Peter T and his folk at TAA produced lots of equally useful material. I really think that a lot of the 60s-80s Australian airline pilot folks didn't quite understand just how lucky they were to have such folk as their instructors in the ground schools and their ops eng sections in the day to day stuff.

As an engineer, FT and ops eng happen to be the main interest thrust over my career .. although I ended up spending time in many and varied areas .. just the way things go, I guess.

The long time sorry state of ATPL training needs little comment ... at least, when I was involved actively in a long ago previous life, my theory students were dragged through much of the basics of the nitty gritty .. the exams being a sideline which most managed to pass without too much trouble. Likewise as a sim instructor .. many a student ended up with far more OEI knowledge than the customer may have thought necessary ...

In the PPRuNe environment, I am getting a little out of date with the specifics of the present regulatory operational requirements as I have been out of routine ops eng work in the day job for some years now. However, the basics haven't changed to any extent and, I suggest, the same considerations apply looking at the Regulatory and the sensible Corporate needs.

.. enough reminiscing.

[Pitch Up Authority]

The imposed 2,5% gradient is there for obstacle clearance and so wind has its role to play.

2,5 % is used for all approaches NP till CAT III C if you want.

Does the Approach climb need to be respected at all times? The answer is Yes.
Does the Landing climb need to be respected at all times? The answer is Yes.
Does the Go-Around climb gradient need to be respected? The answer is Yes.

Do you need 2,5 % gradient in still air? The answer is No as long as you make the 2,5 % relative to the ground. Landing Climb gradient and Approach climb gradient will help you to get on the way.

As far as CAT III versus CAT II and CAT I are concerned. During a CAT III with a DH (let's say 50 ft) the aircraft is already changing it's pitch.

In case of a CAT II that is not the case so at 50 ft, the differences are minor.

And last but not least. Not everything is covered by regulations.

The real issue is however that NOT the safety of the passengers is important but yours. If you are fine they will be also.

Time to go to bed, I have a 12 hr flight ahead of me.

[HazelNuts39]

Do you need 2,5 % gradient in still air? The answer is No as long as you make the 2,5 % relative to the ground.
CS–AWO 243 Go-around climb gradient
The aeroplane Flight Manual must contain either a WAT (Weight, Altitude, Temperature) limit corresponding to a gross climb gradient of 2·5%, with the critical engine failed and with the speed and configuration used for go-around, or the information necessary to construct a goaround gross flight path with an engine failure at the start of the go-around from the decision height.

Regards,
HN39

[catpinsan]

Dear asian '82,

You might like to look at these charts (from AIP HongKong - VHHH):

http://www.hkatc.gov.hk/HK_AIP/AIP/AD/HK_AD2-92A.pdf

http://www.hkatc.gov.hk/HK_AIP/AIP/AD/HK_AD2-91A.pdf

see the statement in bold lettering just before the missed approach description.

'pinsan

[aslan1982]

Thank you guys/girls for all your input and help

I just found a very helpful powerpoint presentation that explains the differences quite nicely. Although not an official document, it does explain it in a less compelx way


http://www.google.com/url?sa=t&source=web&cd=5&sqi=2&ved=0CDoQFjAE&url=http%3A%2F%2Fhome.scarlet.be%2Fppleducation%2FPerfo%2520 briefing%2520737.ppt&rct=j&q=icao%20missed%20approach%20climb%20gradient&ei=OVx7TYW2NOiAhAevkPyNCA&usg=AFQjCNGi4s6aGo0iBvsHwDXEqJvFduqAZA&sig2=RciCA276Gma9TEpGIMYfvA

The document states:

Approach Climb

Aircrafts are certified to conduct a missed approach and satisfy a Gradient of 2.1% - GROSS
The configuration is:
One Engine Inoperative
Gear Up
Go Around Flaps (15 on 737)
G/A Thrust
Speed must be <= 1.4 VSR
(Strictly speaking, the Flap Setting must be an intermediate flap setting corresponding to normal procedures whose stalling speed is not more than 110% of the final flap stalling speed)

Landing Climb

Aircrafts are certified to conduct a missed approach and satisfy a Gradient of 3.2% - GROSS
The configuration is:
All Engines Operating
Gear Down
Landing Flaps (30 or 40 on 737)
G/A Thrust
The speed must be >= 1.13 VSR and VMCL
It is also a requirement that full G/A thrust must be available within 8 seconds of the thrust levers forward from idle

JAA Low Visibility Climb

An Aircraft must be certified to conduct a missed approach and satisfy a Gradient of 2.5% - GROSS or the published Missed Approach Gradient
The configuration is:
One Engine Inoperative
Gear Up
Go Around Flap (15 on a 737)
G/A Thrust
This is only applicable if Low Visibility Procedures will be conducted with a DH of below 200 Ft or No DH

Max landing weight

The maximum landing weight for dispatch is the least of the:

Field Limited Landing Weight
Approach Climb Limited Landing Weight
Landing Climb Limited Landing Weight
JAA LVP G/A Climb Gradient Limited Landing Weight
Structural Limited Landing Weight

Procedure Missed Approach Gradient


Some specific procedures require a Net gradient of more than 2.5%. This will be indicated on the Chart
i.e 4.2% at FUERTEVENTURA


So from the charts/info/tables available to me at dispatch, I have

1) Go around Climb 'approach Climb' Limited weights (2.1%)
2) Go around Cat II/III 2.5 % Missed Approach Climb Gradient limited weights - Cat2/3 approaches only
3)Missed Approach Climb Gradient limited weights (3.0%, 3.5%, 4.0%, 4.5% and 5.0%) - valid for NPA, ILS CAT I and CAT II/III
4)Max certified landing weight
5)Field limited landing weight based on current weather

So if the weather is above CAT I, the only chart I would be consulting is the Approach Climb 2.1% assuming no special MACG procedure at airport

If the weather is below CAT 1 and no special MACG procedure, I would refer to both the Approach climb(2.1%) and CAT II/III MACG (2.5%) and take the most limiting

If the weather is above CAT I and there is a special MACG procedure then I would refer to the Approach climb (2.1%) and the appropriate MACG table, lets say 4.5% for FEU and take the most limiting one

Obviously still considering the MLW and the Field limiting landing weight for all.

So after all that - I think Ive got a fair understanding of it all.

[aslan1982]

Thanks 'pinsan for your input

At FUE the is a similar option

MACG 4.0% = DA:270
MACG 2.5% = DA:303

This is an extract from my OPS Manual

The nominal climb gradient of a missed approach based on ICAO PANS-OPS is
2.5%. At any airport where Jeppesen offers a choice of minima based on any
other climb gradient, those associated with a 2.5% missed approach climb
gradient must be used unless the airfield brief contains performance information
enabling the use of a higher climb gradient.

So unless the airfield brief allows us to use the 4.0%, we must choose the higher 2.5% DA

Ive just checked the airfield brief for FUE and all it mentions is that there are two DA's based on 2.5% and 4.0%, nothing else
Also the last time I flew there, I remember the captain saying in the cruise, can you check the MACG table for 4.0% against our est LW and OAT at FUE. I did and we were below the Limiting weight so we selected the lower DA. I.e. The 4.0%. :hmm:

[catpinsan]

BTW what aircraft're you flying, and does the manufacturer provide the MACG limit wt charts or are they developed by your company performance engineers?

Seeing you've raised your level of knowledge (and mine!), here's an extract that may also be of interest.

6.2 CLIMB GRADIENT AND MOC
6.2.1 Initial phase
6.2.1.1 The initial phase begins at the earliest missed approach point (MAPt) and ends at the start of climb point
(SOC). The manoeuvre during this phase requires the concentrated attention of the pilot, especially when establishing
the climb and the changes in configuration, and it is assumed that guidance equipment is not utilized during these
manoeuvres. No turns may be specified during this phase.
6.2.1.2 Climb gradient in the initial phase. In the initial phase the flight track is horizontal.
6.2.1.3 Obstacle clearance in the initial phase. In the initial missed approach area, the minimum obstacle
clearance shall be the same as for the last part of the final approach area except where the extension of the intermediate
missed approach surface backwards towards the missed approach point requires less clearance. (See Figures I-4-6-4
and I-4-6-5.)
6.2.2 Intermediate phase
6.2.2.1 The intermediate phase begins at the SOC. The climb is continued at stabilized speeds up to the first point
where 50 m (164 ft) (Cat H, 40 m (132 ft)) obstacle clearance is obtained and can be maintained. In the construction of
this phase it is assumed that advantage may be taken of available navigation guidance. During the intermediate phase,
the missed approach track may be changed from that of the initial phase by a maximum of 15°.
6.2.2.2 Climb gradient in the intermediate phase. The nominal climb gradient (tan Z) of the missed approach
surface is 2.5 per cent (Cat H 4.2 per cent). A gradient of 2 per cent may be used if the necessary survey and
safeguarding can be provided. Additional climb gradients of 3, 4 or 5 per cent may also be specified. These may be
used by aircraft whose climb performance permits the operational advantage of the lower OCA/H associated with these
gradients, with the approval of the competent authority.
Note.— In case of non-precision approach, any intermediate values (e.g. 3.4 per cent) between 2 and 5 per cent
may be considered.
6.2.2.3 Obstacle clearance in the intermediate phase
6.2.2.3.1 In the intermediate missed approach phase, the minimum obstacle clearance shall be 30 m (98 ft) in the
primary area, and in the secondary area the minimum obstacle clearance shall be 30 m (98 ft) at the inner edge,
reducing linearly to zero at the outer edge. See Section 2, Chapter 1, 1.3, “Obstacle clearance”.
6.2.2.3.2 The OCA/H for the nominal 2.5 per cent must always be published on the instrument approach chart. If
additional gradients are specified in the construction of the missed approach procedure, they and their associated
OCA/H values must be published as alternative options.
Note.— MOC may be obtained by increasing the OCA/H or by a longitudinal adjustment of the MAPt or both.
6.2.3 Final phase
The final phase begins at the point where 50 m (164 ft) (Cat H, 40 m (132 ft)) obstacle clearance is first obtained and
can be maintained. It ends at the point at which a new approach, holding or return to en-route flight is initiated. Turns
may be carried out during this phase.
6.2.3.1 Climb gradient in the final phase. The criteria of the intermediate phase apply.
6.2.3.2 Obstacle clearance in the final phase
6.2.3.2.1 In the final missed approach phase of a straight missed approach the minimum obstacle clearance shall
be 50 m (164 ft) (Cat H, 40 m (132 ft)) in the primary area, reducing linearly to zero at the outer edge of the secondary
area. See Figure I-4-6-4.
6.2.3.2.2 Turning missed approaches have specific criteria for MOC and for the arrangement and extent of
secondary areas (see 6.4, “Turning missed approach”).
Note.— MOC may be obtained by increasing the OCA/H or by a longitudinal adjustment of the MAPt or both. In
addition, obstacles may be excluded from consideration by defining a turn.

[aslan1982]

Im flying 737-800

At the bottom of the charts it says BPS version 3.1 landing analysis software, so I pressure BPS means Boeing Performance Software.

So from this, Id say Boeing provide the data and our engineers include that in their documents which I have access to.

Thanks for the extra info. Always appreciated.

[HazelNuts39]

Aslan1982;

At the risk of appearing pedantic, I think two minor clarifications will complement what you wrote:

Approach climb - From CS-25.121(d)(1):

The steady gradient of climb may not be less than 2·1% for two-engined aeroplanes, 2·4% for three-engined aeroplanes and 2·7% for four-engined aeroplanes, with –Landing climb - From CS-25.119:
In the landing configuration, the steady gradient of climb may not be less than 3·2%, with the engines at the power or thrust that is available 8 seconds after initiation of movement of the power or thrust controls from the minimum flight idle to the goaround power or thrust settingRegarding CS-25.119 - since the landing WAT-limit weight is the lesser of the weights limited by 25.119 and 25.121, and for many airplanes, twins in particular, the one-engine-inoperative requirement is the limiting one, it is quite common that full G/A thrust is not achieved within 8 seconds, although the required gradient of 3.2 % is.

Regards,
HN39

[mutt]

I am not aware of any operator that makes an analysis similar to the one for Take Off for the Go-Around. We do, and we publish WAT tables for MAP at a number of airports.

EK had a GMFO that refused to listen to the performance engineer who resigned for that reason and joined Boeing as a performance engineer Ummmmmm this guy sounds familiar, did he work for another ME airline prior to EK?

Mutt

(BTW, what happened to O_S? I havent seen him post in months?)

[Pugilistic Animus]

(BTW, what happened to O_S? I havent seen him post in months?)

I hope he just having a busy time flying the T7...I have been wondering the same thing, but you know how he can get busy...I can't wait for his return; I was expecting him in this thread to tell you the truth:{

[Pitch Up Authority]

Nice to see what you guys are doing.

Now we are approved a 15 kts tailwind on a CAT I, this may well mean that at 2000 ft higher the wind is 25 kts.

A 2,5% WAT Go-Around (for me WAT = Still Air ?) might not cover me for obstacles. Are you telling me that you make an allowance for that?

As far as I understand the whole thing, the 2,5 % gradient is used to design the procedure and identify the limiting obstacles. As a result you can then come forward with a DA (DH) or MDA and MAP.

Thanks for clarifying that to me.

Cheers PUA

probably better to PM the fellow's ID - JT

[HazelNuts39]

aslan1982;

From the document you posted in your #19:
Procedure Missed Approach Gradient
- A conflict exists between JAR-25 and ICAO (...)
- The case of an engine failure during Go-around is not considered as this is deemed a remote possibilitycatpinsan;

Re yr post #21: The Thirteenth Meeting of the Obstacle Clearance Panel (2003) added the following to the Foreword of ICAO Doc 8168 (PANS-OPS) :
1.5 The design of procedures in accordance with PANS-OPS criteria assumes normal operations. It is the responsibility of the operator to provide contingency procedures for abnormal and emergency operations.Regards,
HN39

[mutt]

Are you telling me that you make an allowance for that? Yep, splays are based on 30kt wind :):) But i have to admit that we only do this in Shiraz due to the missed approach procedure.

I read the name before J_T's edit...... thanks

Mutt

[FlightPathOBN]

The Pans-Ops criteria, nor the FAA 8260.52 consider Engine Out in the procedure design. The missed approach is based on a minimum performance gradient.
As you noted, the criteria nominal climb gradient of 2.5%.
This is a gross climb rate of about 227 feet per nm.
The net climb is about 167 feet per nm.

Check with the performance people...but EO performance for 2 engine aircraft is along the lines of 100 feet per nm depending on temperatures/loading, and I have worked extensively with 65 feet per nm.

EO procedures are separate, and, to date, custom designed.

Most regulatory agencies do NOT want EO procedures in the public realm, and want to direct the aircraft as able.

(this just in, thanks...Hazel!)

Re yr post #21: The Thirteenth Meeting of the Obstacle Clearance Panel (2003) added the following to the Foreword of ICAO Doc 8168 (PANS-OPS) :
Quote:
1.5 The design of procedures in accordance with PANS-OPS criteria assumes normal operations. It is the responsibility of the operator to provide contingency procedures for abnormal and emergency operations.

[mutt]

It is the responsibility of the operator to provide contingency procedures for abnormal and emergency operations.
FlightPathOBN is offline Report Post Reply The interesting thing about this is that when you take "your" contingency procedure to the authorities for a particular airport, they dont want to know anything about it. We have tried on numerous occasions to advise airports about what we are going to do in the event of an engine failure during takeoff, they wont discuss it. Gotta love the power of liability lawyers :\:\

Mutt

[FlightPathOBN]

Well, yes, and no...as the criteria do not support EO procedures, there is nothing for them to do with the procedure, and cant check if you did it correctly, and given that EO is emergency in nature, the 'if able' governs.

It is interesting noting everyones comments in these regards, it helps quite a bit when proposing procedures, and explaining the parameters of the public procedures.

[FlightPathOBN]

Now we are approved a 15 kts tailwind on a CAT I, this may well mean that at 2000 ft higher the wind is 25 kts.


Did you note the 8260.52 tailwind components for turn calculations?

Table 1-3 gives the minimums for turns....you get to 50kts at 1500'

[4dogs]

FlightPathOBN
As you noted, the criteria nominal climb gradient of 2.5%.
This is a gross climb rate of about 227 feet per nm.
The net climb is about 167 feet per nm.

A thousand years and a couple of lives ago, the net climb for 2.5% was always quoted as 152 ft/nm. When did the nm grow another 600 feet? :eek: :eek:

Stay Alive,

[FlightPathOBN]

152 ...its still there...

152/6076=2.5% I am not sure what the heck I was talking about!

[mav2147]

This is realy a very interesting issue to discuss and to try to obtain a correct answer which is not easy, as we can see.

Nevertheless let me introduce a couple of things for reflection.

1- When operating the aircraft (twin engine for instances) am I realy obliged to comply with the restrictions of FAR25 (or JAR/CS25)? Or this is a matter for the constructor when applying for certification of an aircraft model? Do I realy have to make sure that 2.1 % of climb gradient in AppClimb phase is being obtained? This is FAR 25.

Take a look on FAR 25 initial point:
Sec. 25.1

Applicability.

(a) This part prescribes airworthiness standards for the issue of type certificates, and changes to those certificates, for transport category airplanes.
(b) Each person who applies under Part 21 [New] for such a certificate or change must show compliance with the applicable requirements in this part.

2- If I am operating the aircraft (as a pilot or "Operator"-company) my "rules" are the JAR/EUOPS-1 or FAR 121/135/91. Right or wrong?

JAROPS1 states:
JAR–OPS 1.485 General
(a) An operator shall ensure that, for determining compliance with the requirements of this Subpart, the approved performance data in the Aeroplane Flight Manual is supplemented as necessary with other data acceptable to the Authority if the approved performance Data in the Aeroplane Flight Manual is insufficient in respect of items such as:
(1) Accounting for reasonably expected adverse operating conditions such as take-off and landing on contaminated runways; and
(2) Consideration of engine failure in all
flight phases.

FAA stated in PART 121:

Sec. 121.141

Airplane flight manual.

(a) Each certificate holder shall keep a current approved airplane flight manual for each type of airplane that it operates except for nontransport category airplanes certificated before January 1, 1965.
(b) In each airplane required to have an airplane flight manual in paragraph (a) of this section, the certificate holder shall carry either the manual required by Sec. 121.133, if it contains the information required for the applicable flight manual and this information is clearly identified as flight manual requirements, or an approved Airplane Manual. If the certificate holder elects to carry the manual required by Sec. 121.133, the certificate holder may revise the operating procedures sections and modify the presentation of performance data from the applicable flight manual if the revised operating procedures and modified performance date presentation are--
(1) Approved by the Administrator; and
(2) Clearly identified as airplane flight manual requirements.

Amdt. 121-251, Eff. 1/19/96


For me, it looks like in an OEI situation, the performance that is in AFM might not be the one that we are looking for (because once again it is prepared for the Certification Standards).

3 - What about the 2.5% (or greater) in Missed Approach phase?
This a metter of another "rule" - ICAO Doc 8168 PANSOPS.
This is designed and prepared in the assumption that ALL ENGINES ARE OPERATIVE.

In this case, IF ANY DOUBT EXISTS IN OEI YOU (your company) SHOULD HAVE A CONTINGENCY PROCEDURE (MAY BE AWAY OF THE MISSED APP TRACKING).

Another way to look at it is that weather conditions might interfere in the DECISION PROCESS.
If in VMC why to think in Decision Altitude at 200 feet? You can decide earlier and "COMMITTED TO LAND" at a higher altitude (1000 feet AAL for instance).
In this case if any thing goes wrong and Go Around in OEI is initiated, you are well above the requirement of the Doc 8168 (or TERPs in your case).

Conclusion:
For me what is important is that I AM SAFE (SAFETY FIRST) but I AM OPERATIONAL (Commercial Pilot).
What is SAFE?
The industry says that "have to clear all obstacles by 35 feet (50 feet in turns greater than 15º)"

Which means, IF YOU YOU ARE IN A "NET" CLIMBING AND CLEAR ALL OBSTACLES (even Visually is contemplated) then you are SAFE.
This is legislation then, WE ARE LEGAL complying with it.

Remember that TERPS / PANSOPS design Missed Approach with obstacle clearances of 98 feet and 164 feet in intermediate phase WHICH ARE MUCH HIGHER THAN THE FAR 121 and EU OPS-1 (35 feet).

This is another view of the problem
Best Regards

[HazelNuts39]

mav2147;

You're not really new here, are you? You think it's fun to keep posting the trollish nonsense you posted earlier as Skky?

[de facto]

So unless the airfield brief allows us to use the 4.0%, we must choose the higher 2.5% DA
Dont forget the vis that goes with it....

Also the last time I flew there, I remember the captain saying in the cruise, can you check the MACG table for 4.0% against our est LW and OAT at FUE. I did and we were below the Limiting weight so we selected the lower DA. I.e. The 4.0

Always a good idea to check,but figure should be about the same as on the loadsheet unless you saved loads of fuel,by that i mean its better to know your expected climb restrictions before you take off in case dispatch guys were snoozing...

[mav2147]

I am new here but not in the business.
Almost 43 years of experience and not behind a desk. Really "aviating" every day.
I am not Skky but always in the sky trying to earn my money in the most professional way.

My post is just "another" "different" way to look to this issue.

This is a matter of the legislation that you are in. And you are talking, and discussing, about the "certification rules" (one engine inoperative). But we are not certifying the aircraft when we are flying it. We are "operating it".

My point is that now, operating it, we have to apply different legislation/rules.

And for the Missed Approach, AIPs applies ICAO Doc 1868 and the gradients expressed there are for ALL ENGINES operative. In the same document ICAO states that "operators have to create a CONTINGENCY PROCEDURE in case of an engine out condition".

You might establish your "contingency" flying the same route/track as the Miss App Procedure contemplates, but in this case you are committed to the
"lower gradient", if possible, which permits "higher weight" with HIGH Temperatures and in OEI (One Eng Inoperative). Otherwise your company is loosing money because you are not carrying the contracted payload (i.e. PAX/Bags).

But looking into another set of rules/legislation, the JAR/EU-OPS-1, in it's ACCEPTABLE MEANS OF COMPLIANCE AND INTERPRETATIVE/ EXPLANATORY MATERIAL (AMC & IEM), sates this, for example:

(Quote)
IEM OPS 1.510(b) [and (c)]
Landing – Destination and Alternate Aerodromes
See JAR-OPS 1.510(b) [and (c)]
[ ] [The required missed approach gradient may not be achieved] by all aeroplanes when operating at or near maximum certificated landing mass and in engine-out conditions. Operators of such aeroplanes should consider mass, altitude and temperature limitations and wind for the missed approach [ ]. [As an alternative method,] an increase in the decision altitude/height or minimum descent altitude/height [and/or a contingency procedure (see JAR-OPS 1.495(f)) providing a safe route and avoiding obstacles, can be approved] [ ].
[Amdt. 3, 01.12.01]

(Unquote)

What do you take from this statement? Is my point of view a "trollish nonsense" as you mention?

I am not nuts; and I am not a fool. I am just THINKING WITH MY HEAD with an OPEN MIND.

Best regards

[HazelNuts39]

I am not nuts; and I am not a fool. I am just THINKING WITH MY HEAD with an OPEN MIND.If you are not Skky and not just copying him, then read the thread, in particular John Tullamarine's posts #3 and #11, before posting "another different way to look to this issue".