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TOPCAT for the NG and 777

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Firstly (is that a word?), according to http://www.flightsimsoft.com/topcat/?p=types TOPCAT doesn't even support the PMDG 777, 

I simple search and

http://www.flightsimsoft.com/downloads/ 

 

O well.....


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I simple search and

http://www.flightsimsoft.com/downloads/ 

 

O well.....

 

So I was right. Their product page is outdated. Logically the first place I looked for compatibility information was the Topcat - Aircraft Types supported page.

Not sure what your "o well" is supposed to mean.

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Sorry you made the statement


TOPCAT doesn't even support the PMDG 777

 

Logically the first place to look is the Down load page, where you DL Topcat and there it is....so people don't need to go looking else where its very clear as you should be able to see below. Your statement was wrong so we are just pointing out it does work with the 777.

Just a mistake we all make them.

Untitled960d7.jpg


David Murden  MSFS   Fenix A320  PMDG 737 • MG Honda Jet • 414 / TDS 750Xi •  FS-ATC Chatter • FlyingIron Spitfire & ME109G • MG Honda Jet 

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Sorry you made the statement...Logically the first place to look is the Down load page, where you DL Topcat and there it is....so people don't need to go looking else where its very clear as you should be able to see below. Your statement was wrong so we are just pointing out it does work with the 777.

Just a mistake we all make them.

To be fair I said "according to http://www.flightsim...topcat/?p=types TOPCAT doesn't even support the PMDG 777". Quotes work much better when used in full context.

I disagree though. If I want to know what a product supports I would naturally go to the product information or FAQ page (or similar).

I don't go to the downloads section.

 

I wouldn't go the download section of PMDG to see if their planes are supported in XP-10 or not. That's what the product page is for, and TOPCAT has it's own product page which I linked above.

If the information should be anywhere, it should be there.

 

Anyway...seems they do support the 777. Thanks for the information.

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Kyle,

 

I'm going to have to disagree with you on this one. 

 

A "clearway" is not an area beyond the runway used to contain an aircraft in the event of an excursion.  That area is known in the US as the Runway Safety Area (RSA) or in ICAO-speak as the Runway End Safety Area (RESA).  In the US, the RSA typically extends 1000' beyond the end of the runway and is 500' wide centered along the runway centerline.  If there is less than 1000' RSA available, then ASDA is typically reduced to obtain the 1000' RSA length or an EMAS arresting system is installed.

 

A clearway is an area beyond the end of the runway that meets certain obstacle clearance requirements that is designated by the airport operator for use in takeoff distance calculations.  When a clearway is declared, its usable length is include in the declared TODA.  On a dry runway takeoff, the takeoff distance (both all-engines-operating takeoff distance and the OEI takeoff distance) to 35' is limited by the TODA.  The takeoff run, or the takeoff distance to a point equidistant from the lift-off point to the point where the aircraft reaches 35' cannot exceed the length of the runway (declared TORA). 

 

Clearways as a concept were introduce in the early 1950's to address space constrained airports in Europe.  It was a way to add extra payload but not build longer runways.  The first US turbojet rules (SR422) did not permit the use of either a stopway or a clearway.  When it became clear (pardon the pun) that US operators could benefit from the concept of clearway and stopways, the rules were changed with SR422A and SR422B to permit the use of both a clearway and a stopway.  Until recently, US airport policy has been to build runways long enough that a clearway is not needed.  However, that thinking has changed, and now some US airports have clearways.  Clearways have been in Europe for a long time.

 

If the runway is wet, a clearway is not usable since the OEI takeoff distance screen height is reduced from 35' to 15'.  That was too much of a reduction for regulators to agree to back in 1998 when the US wet runway rules went into effect for appropriately certificated airplane types.

 

The amount of clearway usable is included in the declared TODA, and the amount of stopway is included in the declared ASDA.  For US airports, declared distances are published in the Airport/Facility Directory (Google AeroNav Products for the e-version of the A/FD).   If it a Part 139 airport (air carrier ops) and it is not included TODA (i.e. TODA > TORA) in the A/FD, then the clearway doesn't exist regardless of what the airport says (ref: AC 150/5300-13A).

 

In rare instances, TORA will be less than TODA even though a clearway has not been declared.  This occurs when the Runway Protection Zone (trapezoid area beginning 200' beyond the end of the runway that is to be free of undesirable activities, like schools) overlies something it shouldn't.  That can result in TORA being less than the physical length of the runway and TORA being less than TODA, yet no clearway is provided.

 

Rich Boll

Wichita KS


Richard Boll

Wichita, KS

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I'm going to have to disagree with you on this one. 

 

Please go back and re-read my post. Specifically, re-read the last sentence of the paragraph you object to.

 

By definition, you're absolutely right. In practice - or in other terms - how we designed them when I worked on a team of airport planners.

 

 

 


Until recently, US airport policy has been to build runways long enough that a clearway is not needed.

 

Wonder why we still include them, then...  :wink:

 

 

 


In rare instances, TORA will be less than TODA even though a clearway has not been declared.  This occurs when the Runway Protection Zone (trapezoid area beginning 200' beyond the end of the runway that is to be free of undesirable activities, like schools) overlies something it shouldn't.  That can result in TORA being less than the physical length of the runway and TORA being less than TODA, yet no clearway is provided.

 

Yep. One of the principal reasons we recommended BCB move their entire runway. The RPZ was being penetrated by buildings off of the departure end of 12, and the owners didn't want to relocate so we could demolish. Plus, there was a safety concern with a runway excursion putting an aircraft on Main Street.

 

...again, not by definition, sure, but the clearway is also there in practice in the case of an excursion.


Kyle Rodgers

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Kyle,

 

What you said is that a clearway is the area beyond the paved runway that has been made clear in the case of a runway excursion.  That is a definition that more closely describes a RSA or REAS.  I say closely because in the US the RSA could include the runway.

 

A clearway does not need to be clear of obstructions, only that obstructions do not penetrate the 1.25% clearance plane except for runway threshold lights that are located off to the sides.  It does not even have to be "ground". It can water, it can the be the area off of a cliff .  FAA makes it clear that clearway need not be suitable for stopping the aircraft in the event of runway excursion (ref: AC 150/5300-13A, Airport Design, paragraph 311c). All that is required is that it is under the control of the airport operator, it is so designated as such, and that no fixed or moveable object penetrates the clearway plane.

 

On the other hand, the RSA must be graded & constructed such that it is capable of supporting an aircraft of design size (ARC or RRC) in the event of a runway excursion.  In many cases, an RSA that lies beyond the end of the paved runway "could" qualify for a clearway.  However, in practice that does not happen, or at least I haven't seen it. 

 

I would be curious to know about any US airport, especially a part 139 airport, that has clearway.  I have seen a few odd-ball TODA > TORA examples (e.g. Concord, CA - KCCR), but that is mostly due to RPZ requirements.  The only airport that I found that actually had a clearway (and a stopway) that conformed to the FAA requirements was Glasgow MT (KGGW), which had declared distances and A/FD entries that supported the designation.  However, that was a few years ago, and they have since re-surveyed their runways and eliminated both the clearway and the stopway on their runways.

 

 

Rich Boll


Richard Boll

Wichita, KS

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What you said is that a clearway is the area beyond the paved runway that has been made clear in the case of a runway excursion.  That is a definition that more closely describes a RSA or REAS.  I say closely because in the US the RSA could include the runway.

 

[Long dissertation that conveniently ignores my earlier reference to the sentence that matters]

 

Rick,

 

I appreciate your willingness to share knowledge, but at this point, I'm getting the impression you're simply trying to discredit me instead of actually just share knowledge.

 

The sentence I referred you back to earlier was this:

"It's included in TODA as it's space available for the climb out and for emergency use."

 

...or, to pinpoint my reference that was directly in line with both of your posts:

 

"It's included in TODA as it's space available for the climb out [...]."

 

That is what the clearway is there for by definition. Both of us have stated this. It is clear we're in agreement, despite your continued discussion.

 

The disagreement seems to stem from not understanding that, in a practical sense, airport planners are using clearways as an extra measure of protection in the case of excursions. It might not be the definition or original intention of a clearway, but that's some of the methodology behind current planning and development.

 

Think about it:

Climb performance over an obstacle really hasn't been much of a factor since we stopped using JT3Ds, which somewhat lends its hand to your earlier point that a lot of US Airports don't have them. Therefore, if one is there, it's probably there for runway excursions (or to meet some other requirement for a surface or zone).

 

Regardless, my earlier point is just fine. I clearly referenced the clearway being used for the initial climb, despite the point being secondary to my mention of how it's currently being used in practice.


Kyle Rodgers

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No one is trying to discredit you, just point to the error in the statement that a clearway is used for runway excursion.  Your other comments concerning clearway are correct, that's why I didn't mention them nor felt the need to do so.

 

Climb performance over an obstacle is still an issue. As a business jet pilot, I see obstacle limited takeoffs on the airport analysis, even at part 139 airports.  A clearway was never about getting over an obstacle. It was used to allow extra distance to complete the takeoff climb to 35' feet.   In fact, using a clearway is only possible when obstacles are not a factor in the takeoff since using a clearway places the start of the net takeoff flight path closer to the obstacle.

 

Rich


Richard Boll

Wichita, KS

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Yes, Clearway is meant for take-off and getting got 35' within the TODA

 

But!:

 

 

 


In fact, using a clearway is only possible when obstacles are not a factor

 - not as much

 

Using a runway/particular aircraft/specific payload/de-rated thrust is only possible when obstacles are not a factor. They're separate calculations. Yes a clearway would bring an aircraft closer to any given obstacle at 35' in the air, but that doesn't mean it's going to hit it just because it's using a clearway. As i'm sure you know, it depends on a wide number of factors.

 

Both calculations are separate (though the obsacle calc isn't independent), and the obstacle clearance calculation on some models of aircraft is dependant on the result of the takeoff distance calculation, and as such, you wouldn't be able to say "Clearway only works if there are no obstacles"

 

Now, for specific aircraft A, at weight B, for runway C, in conditions D, the clearway may very well only be usable with no obstacles through Obsacle Identification Surface E based on a TODA that uses a clearway. 

 

But look at how many variables must come together to make that statement work! As such I can't accept that "using a clearway is only possible when obstacles are not a factor".

 

I would revise it as saying "Using a clearway changes the distance a specific obstacle must be at in order to clear it"

 

I'm not saying this to pick on you, but rather to make sure that people following this post don't fall under the impression that an obstacle on the take-off path precludes the use of the clearway in the takeoff calculations - that simply isn't the case for all aircraft. It all depends on the math.

 

Luc

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The 777 and freighter are supported byTOPCAT the page must be out of date.

 

Whatannoys me about TOPCAT for the 777 and the 737 is that the N1 percentages calculated by it never correlate with actual thrust settings. So say (this is just a wildly inaccurate example of the top of my head) but if you calculate for a D-TO1 Takeoff at 44 degrees on TOPCAT, that will give an N1 of say 84.6%, yet when you insert 44 degrees D-TO1, it actually gives a thrust setting of 86% (or whatever). The V-speeds never match with the PMDG FMS figures either, for 777 or 737.

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The 777 and freighter are supported byTOPCAT the page must be out of date.

 

Whatannoys me about TOPCAT for the 777 and the 737 is that the N1 percentages calculated by it never correlate with actual thrust settings. So say (this is just a wildly inaccurate example of the top of my head) but if you calculate for a D-TO1 Takeoff at 44 degrees on TOPCAT, that will give an N1 of say 84.6%, yet when you insert 44 degrees D-TO1, it actually gives a thrust setting of 86% (or whatever). The V-speeds never match with the PMDG FMS figures either, for 777 or 737.

 

Well, didn't someone say it's still a beta? Probably don't have all the bugs ironed out.

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Luc,

 

You are absolutely correct, and I stand corrected on that statement. I have discussed clearways with various performance engineers and the issue of obstacle clearance always comes up.  Obstacles present in the takeoff path do not preclude the use of a clearway provided they can cleared by net takeoff flight path that begins over the clearway. 

 

The point I was trying to make is that a takeoff weight that is obstacle limited without considering the clearway will be further weight limited by the use of a clearway. The only exception being the use of an improved climb performance V2 speed to clear a distant obstacle where the clearway could be used to obtain the longer takeoff distance and the higher V2 speed.

 

Sorry for mangling my explanation. And, thanks for bringing that up!

 

Rich


Richard Boll

Wichita, KS

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I agree - the takeoff segment that follows the 35' portion is typically more restrictive in performance calculations than the TODR calculation.

 

That being said, I'm imagining some special plane that has landing gear with parachute-like drag, that once the gear is retracted it can rocket into the air really fast, and badly needs the clearway until that gear comes up ;)

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