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Approach Climb Gradient vs EOSID

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Approach Climb Gradient vs EOSID

Old 12th Apr 2011, 00:58
  #141 (permalink)  
 
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what terrain clearance do you provide in the missed approach procedures you design, or do you put the "required" gradient on the chart?
The charts that I provide are certainly custom. They are RNP transition to a GBAS final, or just RNP. With the custom, all is coded, the missed approach and EO missed are coded, and therefore the alignment is reflected on the chart, if allowed by the regulator. SID and EO departures are shown on different plates.

Typically, the charts have a set DA/MDA, required gradients are not shown on the chart, as the entire procedure is coded in, and the procedures are custom designed for the aircraft.
The approach, same as the public criteria, is based on the coldest day of that airport (ie lowest effective GPA) with the required ROC.
The missed is based on the hottest day, max landing weight based on the elev/performance, etc to get the min net per the criteria.

Now, I do have charts with performance DA's. This is a specialty of my firm, operations based navigation, hence the name.

These procedures are based on the missed AND the required gradient is provided. The approach is still the same basis as above, but the missed is based on a real time performance for the aircraft/airport. So if the operator, based on weight/temp/etc determines the climb grade, at 6.5%, this is the DA/vis required. These CG range from the criteria 2.5% up to 12%. This design does not include any EO missed, that is separate.

For the obstacle clearance, where to begin...
Depends on several factors, rad alt, baro, head loss, and momentary descent for the particular aircraft, latency, exposure time, prox and regulators.

For all engine, the respective criteria clearances are used. This somewhat assures that the state is maintaining the obstacle database, and from a liability perspective, I consider this the BARE minimum.

For EO, I try to use the criteria obstacle surfaces, but can fall back to the 35 foot min with turn additives, etc. Turn additives and winds are significant factors in obstacle clearances. There are also mountainous and precipitous terrain additives

Another big factor is the respective aircraft and the prox warnings...some regulators allow for a prox warning on EO, others do not. a Smiths/Honeywell/thales/etc all have different settings for the warning, so that is really a wildcard in the design.

So...long story short, there is a combination of many factors when looking at a 'clearance' in the design. Clearances can be real of assumed additives.

The coded procedure has met the approval of all of the applicable minimums and worst case scenario given.
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Old 12th Apr 2011, 01:20
  #142 (permalink)  
 
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Interesting! Thanks.

But, if
required gradients are not shown on the chart, as the entire procedure is coded in, and the procedures are custom designed for the aircraft.
How does the crew know what weight they can do the approach at and still successfully complete an EO Missed Approach up to the MSA/LSALT?
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Old 12th Apr 2011, 01:35
  #143 (permalink)  
 
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in some respects 2 separate issues.

In PBN procedures...or in airport procedures EO are NOT accounted for. EO is completely up to the operator. If you want to use the public plates, you have to limit you weights, based on CG to get the 2.5%. As temps rise, you limits weights...

In a coded procedure, If you select the EO, you know that all of the mins have been accounted for.

If one looks at the performance with temps, this really limits MTOW. You an still get 2.5%, but as temps rise MTOW gets you to the paint on the aircraft.

To open up departures, a custom EO is designed, with temps and obstacles, to show the regulators, one can navigate an EO with extended weights.

Given climate change, either you will be sitting on the ground more often, be severely weight limited, or you will have a custom EO design.
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Old 13th Apr 2011, 06:36
  #144 (permalink)  
 
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Given climate change, either you will be sitting on the ground more often, be severely weight limited, or you will have a custom EO design.

I was just recently speaking to my expert contact on climate change, Ms Tooey...currently Mrs Hollaway,....becuase it's all a bunch of Horse hooey...

skip to 8:30...

seriously interesting topic...but I've put to rest climate change on JB...as scientific nonsense...and if you'd take note of my location...
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Old 13th Apr 2011, 14:45
  #145 (permalink)  
 
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hahaha...

Climate change is real...its just not man-made....

you have to figure how oil is formed, millions of years of warm, tropical temperatures, vegetation is compressed to form the oil....

where are some of the biggest reserves? the North Slope in Alaska.....
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Old 13th Apr 2011, 18:59
  #146 (permalink)  
 
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FPOBN

Only major changes in earth's orbital mechanics can account for major climate change...i.e wobble and tilt...incidentally CO2 levels rise during warm periods because of higher rates of cellular respiration and greater biological productivity...

come join us...

http://www.pprune.org/jet-blast/2833...ebate-192.html



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Old 13th Apr 2011, 23:54
  #147 (permalink)  
 
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Originally Posted by FlightPathOBN
EO is completely up to the operator. If you want to use the public plates, you have to limit you weights, based on CG to get the 2.5%. As temps rise, you limits weights...
This goes to the heart of what I have been asking.

So if I use one of the "public" plates, then I just need to achieve 2.5%? I assume that will give me 35ft obstacle clearance up to the MSA. I can cope with that.

In a coded procedure, If you select the EO, you know that all of the mins have been accounted for.
How do you present the gradient info to the operator so that they can work out the maximum weights for a procedure, or do you crunch the performance numbers for an EO and provide that data to the operator?
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Old 14th Apr 2011, 00:28
  #148 (permalink)  
 
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Cap,

I wish it was that simple...

So if I use one of the "public" plates, then I just need to achieve 2.5%? I assume that will give me 35ft obstacle clearance up to the MSA.
The 35 feet is not based on a 2.5% CG, the 35 feet is based on SID, the min obstacle clearance plane is based starting at the end of the runway, sloping up, with a min CG gradient of 3.3% The aircraft is assumed, for criteria calculations, to be at least 35 feet above the end of the runway. This 'surface' is what one needs to clear.


If, and IF, you have a 2.5% CG with EO Missed Approach, it may work, but you have to look at all of the factors. (just dont turn for a while)

How do you present the gradient info to the operator so that they can work out the maximum weights for a procedure, or do you crunch the performance numbers for an EO and provide that data to the operator?
With a coded procedure, it is a combination of worst case factors...highest temps for the airport, bleeds, etc on performance...this generates a max weight. We have to remember that the procedure for the public criteria is based on an ISA delta. So we try to design a path, that extends the weight limits aside from the public procedure.

Designs are good for a certain temperature. You may have an airport where the ISA D is always high, and you will always be weight limited for that airport. This is something that the people back in the office are always calculating the load diagrams for that aircraft. (you think ATC has it tough, look at what these people do)
Your aircraft should not have been loaded higher, using the the real-time temp at the destination, than all of these factors.
I am not sure of the SOP on EO, but many airlines contract EO procedures, just so they can extend weight limitations past the required 2.5% CG.

Last edited by FlightPathOBN; 14th Apr 2011 at 00:46.
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Old 15th Apr 2011, 19:06
  #149 (permalink)  
 
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legal requirements for the TO case mandate that a NTOFP...that clears all obstacles vertically by at least 35' and 200' horizontally within the airport boundaries...and 300' horizontally after passing the boundaries....The NTOFP is the actual flight path reduced by 0.8, 0.9,an 1.0...for twins, trijets and quads, respectively until a height of 1500' above the airport elevation,...after that it is a performance engineer's* art...

this thread needs a little Krupa














* J_T, O_S and Mutt
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Old 15th Apr 2011, 19:32
  #150 (permalink)  
 
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ummmm...are you explaining the profile

an engine out missed profile looks nothing like this...

there are also missed approaches that turn before the end of the runway...
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Old 15th Apr 2011, 20:24
  #151 (permalink)  
 
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Since the beginning of this thread, I've not yet figured out whether this thread is about departures or approaches...
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Old 15th Apr 2011, 20:53
  #152 (permalink)  
 
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its 2 (click) 2 (click) 2 threads in one....

at our company we are required to fly the EOSID in case SE missed approach at certain airports and OAT.
The thread has tried to illustrate the differences between EOSID and EO missed.

How are we doing?
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Old 16th Apr 2011, 01:12
  #153 (permalink)  
 
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All engine operating SIDs, ODP, and missed approaches assume a constant gradient; i.e, no level segment for acceleration.

Perhaps that is understood here, but I am not so sure.

In the United States, if the constant slope for the SID, ODP, or missed approach is greater than 200 feet per mile, then a 24% additive is factored in to compensate for more likely performance errors.

Having said that, the FAA is seriously considering doing away with the 24% additive for two reasons: 1. The smart, conservative guy who sold the concept has been retired for some time now. 2. The airline lobby doesn't like the additive because it can affect payload (read: revenue).
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Old 21st Apr 2011, 17:52
  #154 (permalink)  
 
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Cool GA Climb Gradient

Capn Bloggs,

Forgot to mention (busy with the Senate) that a handy page for you to contemplate is page 4.7 of the Performance Engineers Manual (Andy has it!) which gives you the Gross GA Climb Gradient (OEI, A/C Off, Gear Up, F18 and with icing corrections) as a function of airport Pressure Altitude and Ambient Temp, weight and airspeed. Unfortunately, it is in pounds...

Stay Alive,
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Old 22nd Apr 2011, 01:22
  #155 (permalink)  
 
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Thanks Dogs. I'll check it out.
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