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Nyxx

TOPCAT for the NG and 777

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I use PFPX for every flight. I try to do everything by the book, its just the way I like to do it.

 

Now Q

To me Topcat seems to add very little, as I use the CDU for V speeds and landing speeds.

 

So please explain what extra Topcat brings to the table. Does it make very little difference or just add that extra touch?

 

Is it worth it?

 

I like the way it works with PFPX and yes I do know its a different program to PFPX  :wink: for take off and landing calculations. 

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Basically TOPCAT is there for calculating takeoff performance, the fmc is very limiting in it's function.

 

Topcat gives you derate settings dependant on weight and it is very rare to use full thrust.

 

I did a 306,000kgs 777-300er flight from London to Hong kong and with a different tool I got a derate of nearly 50C (to thrust)

 

Yes, I think it's a really worthwhile investment for takeoff

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So please explain what extra Topcat brings to the table. Does it make very little difference or just add that extra touch?

 

Your FMC is providing what they call "balanced field" calculations. While this takes into account runway length (one of the reasons you don't get prompted with v speeds until you select a runway from the database), it's assuming whatever thrust rating you've thrown in there (which, unless you've used a takeoff calculator, it's a best guess).

 

Basically, you can work forwardly or you can work backwardly. What the FMC is doing is working forwardly: for a given thrust setting (or derate), with these conditions, and this runway, your v-speeds will be this. What TOPCAT allows you to do is work backwardly: for this runway and these conditions, you can use a thrust setting (or derate) up to this level, with these v-speeds and still safely operate on the runway. This is done for engine cost measures (not fuel savings). The calculator will also give you a table with the relevant margins. This margin is the runway remaining by the time you come to a stop if you were to abort the takeoff at V1. The size of an acceptable margin is up to the SOP or the PIC. I prefer my margin to be at least 500', but that's just me.

 

Additionally, the FMC is only concerned with the field itself. There are also restrictions for climb gradients and so on after the departure that a takeoff calculator would take into account (this is shown by TOPCAT in a CODE column that reports "FIELD" or "CLIMB/OBS", which you can see below).

 

3.jpg

(The CODE in this case - "OBS" - shows that the performance limitation is not the runway itself, but the performance necessary to climb above obstacles on departure. Image provided by AVSIM.)

 

Essentially, what you're getting is field-specific values that allow you to operate a little more realistically regarding de-rates (and/or assumed temps), and climb gradients.

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OK, good info, thanks Kyle for all that info, since I own PFPX and fly 90% of the time the NG/777 i will get it.

 

Thanks.

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OK, good info, thanks Kyle for all that info, since I own PFPX and fly 90% of the time the NG/777 i will get it.

 

Thanks.

 

Welcome. Just as a heads up: while TOPCAT does have the option to adjust the weights in aircraft.cfgs, do not utilize this function with PMDG aircraft.

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I would checkout TOPER 777 you also get it for the 737NG, this software takes uses the climb segment 1 and 2 gradients into account when performing calculations. Unlike TOPCAT

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I would checkout TOPER 777 you also get it for the 737NG, this software takes uses the climb segment 1 and 2 gradients into account when performing calculations. Unlike TOPCAT

 

This isn't true, actually. TOPCAT does address climb segment one (as shown in the above screenshot).

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Yeh from VLOF to gear up! But i think the second segment is more demanding as you'll be away from the TODA

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Yeh from VLOF to gear up! But i think the second segment is more demanding as you'll be away from the TODA

 

Where, exactly, are you getting this information?

 

Also, TODA is "take off distance available" - if you're into the climb segment, you're definitely not worried about TODA anymore...

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I only use TOPCAT to see how much of a de-rate is possible, then I use the CDU reference speeds which slightly differ from what TOPCAT calculates.

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Well the 1st seg starts at VLOF

 

Operations manual from a 737 NG pilot

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Yeh plus clearway

 

No. TODA is TODA. TODA is not TODA plus clearway. TORA plus clearway is TODA.

 

Well the 1st seg starts at VLOF

 

Operations manual from a 737 NG pilot

 

Yes, but again, TODA isn't a concern when you're in the climb.

 

...and I highly doubt an FCOM refers to TOPCAT, here. I meant "where are you getting this information about what TOPCAT does and doesn't do, related to climb calculations?"

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No. TODA is TODA. TODA is not TODA plus clearway. TORA plus clearway is TODA.

 

You have it wrong.

 

TORA is just runway length nothing more.

 

TODA - RUNWAY + CLEARWAY.

...and I highly doubt an FCOM refers to TOPCAT, here. I meant "where are you getting this information about what TOPCAT does and doesn't do, related to climb

 

Nope its not an FCOM. Its far away from that. The pilot got it issued from his company about performance of the 737NG

 

Very highly detailed

I read on the TOPCAT forum it doesn't use it and thats from the producer

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You have it wrong.

TORA is just runway length nothing more.

TODA - RUNWAY + CLEARWAY.

 

I appreciate your thirst for knowledge, but it appears that you've taken a wrong turn...

 

Take Off Distance Available

Definition

The length of the take off run available (TORA) plus the length of the clearway, where provided.

http://www.skybrary.aero/index.php/Take_Off_Distance_Available_(TODA)

 

This is becoming a problem, honestly. If you don't know what you're talking about, please refrain from posting and wait until the topic is about something that you understand.

 

You're trying to argue with a guy who worked in airport planning, which requires intimate knowledge of these various definitions.

 

 

 


I read on the TOPCAT forum it doesn't use it and thats from the producer

 

Link?

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AR-OPS 1.480 (a)(9) TakeOff Run Available (TORA): The length of runway which is declared available by the appropriate authority and suitable for the ground run of an aeroplane taking off. TORA is either equal to the runway length, or to the distance from the runway entry point (intersecting taxiway) to the end of the runway


JAR-OPS 1.480 (a)(7) Takeoff Distance Available (TODA): The length of the takeoff run available plus the length of the clearway available.


 

 


This is becoming a problem, honestly. If you don't know what you're talking about, please refrain from posting and wait until the topic is about something that you understand.

 

Maybe you can say that to the flight operations who wrote this manual and which i am reading from and studying

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AR-OPS 1.480 (a)(9) TakeOff Run Available (TORA): The length of runway which is declared available by the appropriate authority and suitable for the ground run of an aeroplane taking off. TORA is either equal to the runway length, or to the distance from the runway entry point (intersecting taxiway) to the end of the runway

JAR-OPS 1.480 (a)(7) Takeoff Distance Available (TODA): The length of the takeoff run available plus the length of the clearway available.

 

Maybe you can say that to the flight operations who wrote this manual and which i am reading from and studying

 

Re-read what you wrote above, versus what is being said right here.

 

"AR-OPS 1.480 (a)(9) TakeOff Run Available (TORA): The length of runway which is declared available by the appropriate authority and suitable for the ground run of an aeroplane taking off. TORA is either equal to the runway length, or to the distance from the runway entry point (intersecting taxiway) to the end of the runway"

This doesn't address TODA at all. It does discuss what TORA is.

 

"JAR-OPS 1.480 (a)(7) Takeoff Distance Available (TODA): The length of the takeoff run available plus the length of the clearway available."

This confirms exactly what I said above. This quote essentially says TODA = TORA + clearway.

 

You claimed that I was incorrect for saying that TODA is simply take off distance available by saying "yeh, plus clearway." This is incorrect by the definitions you've listed above. You then attempted to clarify in post #15 with: "TODA - RUNWAY + CLEARWAY." Again, false. It's TORA + Clearway. The clearway continues beyond the paved runway, so the use of "runway" is too ambiguous for the purposes of the discussion here.

 

I'm still waiting for that TOPCAT reference, by the way.

 

EDIT: I went over to TOPCAT and found several references to data for both 1st and 2nd climb segments. The only time I saw something referencing a limitation of providing climb performance is with the Airbus data: http://www.topcatsim.com/forum/index.php?topic=571.msg2417#msg2417

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Take Off Distance Available

Definition

The length of the take off run available (TORA) plus the length of the clearway, where provided.

http://www.skybrary....vailable_(TODA)

 

To be fair, Kyle -- isn't that what Vernon said?

 

TODA - RUNWAY + CLEARWAY.

 

 

You must reach a 35' (in the dry) screen height by the end of the TODA, which would include any clearway.

 

After that, you're in to the second-segment climb at Vwith gear retracted and flaps in the takeoff configuration to acceleration altitude, and I agree that at this point you're not bothered about the TODA or anything else to do with the runway environment.

 

At least that's my understanding of it!

 

EDIT: ah, I see what you mean!

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I use Toper Web, because there are no Topcat profile for 77W, it's quite handy but it doesn't have fixed derates, only assumed temperature.

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You claimed that I was incorrect for saying that TODA is simply take off distance available by saying "yeh, plus clearway." This is incorrect by the definitions you've listed above. You then attempted to clarify in post #15 with: "TODA - RUNWAY + CLEARWAY." Again, false. It's TORA + Clearway. The clearway continues beyond the paved runway, so the use of "runway" is too ambiguous for the purposes of the discussion here.

 

Yes i may have worded things differently but were still speaking of runway available + Clearway

 

I may have got things mixed up basically; Stopway  =  ASDA - TORA 

                                                           Clearway =  TODA - TORA


 

 


You claimed that I was incorrect for saying that TODA is simply take off distance available by saying "yeh, plus clearway.

 

Yes i assumed you knew TODA has runway length so i only said plus clearway


From the 737 NG performance manual

 

TAKEOFF RUN AVAILABLE (TORA) is the runway length

 

TAKEOFF DISTANCE AVAILABLE (TODA) is the runway length plus available clearway

 

ACCELERATE STOP DISTANCE AVAILABLE (ASDA) is the runway length plus available stopway

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Yes i assumed you knew TODA has runway length so i only said plus clearway

 

Not plus clearway -- including clearway.

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Yes i may have worded things differently but were still speaking of runway available + Clearway
 
I may have got things mixed up basically; Stopway  =  ASDA - TORA 
                                                           Clearway =  TODA - TORA

 

Correct.

 

 

 


Yes i assumed you knew TODA has runway length so i only said plus clearway

From the 737 NG performance manual
 
TAKEOFF RUN AVAILABLE (TORA) is the runway length
 
TAKEOFF DISTANCE AVAILABLE (TODA) is the runway length plus available clearway
 
ACCELERATE STOP DISTANCE AVAILABLE (ASDA) is the runway length plus available stopway

 

Incorrect.

 

"Yes i assumed you knew TODA has runway length so i only said plus clearway."

 

I referred to TODA. This already has clearway included in it. Your "correcting" my post referencing TODA with "plus clearway" would result in: TODA + Clearway. This would be a doubling in the clearway, or TORA + Clearway + Clearway.

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I referred to TODA. This already has clearway included in it. Your "correcting" my post referencing TODA with "plus clearway" would result in: TODA + Clearway. This would be a doubling in the clearway, or TORA + Clearway + Clearway.

 

Including ;)

Whats incorrect? Those definitions...

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Including ;)

Whats incorrect? Those definitions...

 

Vernon - I'm really not sure where you're not understanding this.

 

I referred to TODA in an earlier post. You then quoted my post with "Yeh plus clearway "

 

You took what I said (TODA) and added "plus clearway." The end result of that would be TODA (my post) + Clearway (your post). If TODA already includes clearway - as you admit, mind you - why would you then try to correct me by quoting a post and adding "plus clearway." That makes no sense. The end result would be TODA + Clearway, which would then essentially mean TORA + Clearway + Clearway. This is not a valid metric.

 

 

 

Additionally, we've still not seen quoted references to TOPCAT not calculating the 1st and 2nd climb segments as you've claimed. Information posted here needs to be - to the best of your knowledge - factual. If you post something in error it would be forgivable, but continuing to dig your heels in and continue arguing about it can be seen as intentionally misleading. This is especially true in this case because your argument is against a paid product.

 

Take a step back. Re-evaluate what your intention was in post #11 versus the definition of the terms that even you, yourself, have provided. While you're doing this, please also go find the reference to TOPCAT not calculating performance for the first and second segments of the climb.

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