Does everyone use TOPCAT?

[Fabo 213]

except the derating is not just about the wear and tear. Engine failure likelihood and, should it happen, controllability are two big things that derating (fixed or AST) makes much better.

 

btw. you will not see it in the NG, but come the 777, you can run into some cases when you are expressly prohibited from taking off without derate. The reason? If you have a very light airplane, it will become uncontrollable on full TO thrust should an engine fail on takeoff.

[Boeing or not going 578]

Derated takeoffs and climbs use MORE fuel, not less, so your accusation that it's a money saving scheme is utterly stupid.

 

A derate is calculated to assure takeoff is achievable with a single engine failing at V1, so it's not dangerous at all. In fact, with assumed temperature derate, you're free to advance power on the operating engine anyway.

 

If you're going to accuse people of ranting then doing so your self, I suggest not doing it from a point of ignorance.

 

A derated takeoff does not use more fuel. And I never once mentioned derated climbs either. So your accusation about my knowledge is baseless.

 

I think it is pretty clear 'gear up' has no idea what he is talking about. since it is not safe to cancel a derate in the event of an engine failure due to Vmcg/Vmca I would be interested to know his views on selecting TOGA on the remaining engine at Vr? From the sounds of it, always use TOGA V speeds..

 

Gear up.. Nothing unsafe about using max derate/assumed temp, nothing unsafe about going TOGA and respecting the time limit on the engines, it is all about understanding the machines limitations and correctly applying the appropriate perf calculations. Hense why this topic started.

 

You can talk all you want about bean counters, however the simple fact is the more you push a machine to its limits the faster it will eventualy fail.

 

Ah yes another troll insulting my knowledge. Of course it's unsafe to derate a takeoff. Plus to claim it prevents engine failure is ridiculous. As if there's a magical difference between say 94% and 90%. Any possible wear that would cause an engine failure no matter what thrust setting was used in the past would usually be found in scheduled maintenance. And that's why an engine would then need more maintenance to look for problems and thus the reason bean counters demand derates.

 

Excuse me?

 

Pot, kettle & black spring to mind.

 

Who are you BTW?

 

It's common practice to sign one's posts with one's real name about these parts - then at lease we can know who we are talking too.

 

Don't feed the troll guys.

 

I'm a troll and pot calling the kettle black? Considering you replied to my short comment about my preferences for not derating takeoffs unless very light was this:

 

If you are old enough to drive legally (wherever you live on the planet) I bet you pull away from traffic lights like an F1 car every time & red line your engine in every gear...Oh!...you don't right?....I wonder why?

 

Perhaps you should look in the mirror and go find another hobby that lets you take your pent up anger out?

 

except the derating is not just about the wear and tear. Engine failure likelihood and, should it happen, controllability are two big things that derating (fixed or AST) makes much better.

 

btw. you will not see it in the NG, but come the 777, you can run into some cases when you are expressly prohibited from taking off without derate. The reason? If you have a very light airplane, it will become uncontrollable on full TO thrust should an engine fail on takeoff.

 

Again, no magical difference between a few percentage points of thrust. Over time yes it leads to more wear which leads to more chances of engine failure, but thats why there would be more work done on said engines that would negate any supposed damage done. Hence the reason why bean counters want the maximum derate possible for each runway length and temperature, etc.

 

And I know all about derating that's done because of lower weights especially powerful power to weight ratio airplanes like the 777 and 747. That's why in my first comment I said "unless light weight" I don't like to derate.

 

And the rest is history, with a bunch of children and a few probable bean counters blowing everything I said out of proportion to help their sad little egos.

[Chase 303]

Gear up and Off, please put a signature with your first and last name in your posts in the PMDG forums.

 

G-CIVA, take a breath man, this topic isn't worth getting angry over.

[Fabo 213]

Boy, you really hate those bean counters, don't you?

 

Alas, you have shown again that you know squat, and unless and until you show you work for GE, Rolls Royce, P&W or SNECMA, I shall ignore your ramblings and I strongly advise everyone else to do just the thing.

[FLEX1978 373]

G-CIVA Chase has got the right idea bro.

 

@Gear up and off - Although the basis of your argument is correct, it is clear that you have tunnel vision regarding the bigger picture. Here's what I suggest, contact every major operator on the planet and advise them of the dangerous practice defined in each and every SOP.

 

Just to be sure, contact the daily mail and every other trash newspaper and let them know that professional flight crew are also blindly following these dangerous procedures with no thought for public safety.

 

You seem to have it all figured out mate Am sure they will see the errors of their ways and demand TOGA take off's.

 

Cheers

[cavaricooper 2,613]

As pilots we are creatures of habit.... One of the biggest arguments for a derated takeoff is the fact that it allows for an accustomed takeoff time window. After 40% the stabilized call TOGA is actioned. There is a hold and thrust set call. Transition to the HIGH SPEED REGIME and things are now VERY different at 80 kts. Then there is a period of TIME TO MONITOR AND REACT. V1 brings another set of rules followed by ROTATE and V2. All of which transitions into a nice two part rotation and pitch for speed. More and more important with massive power on one wing and a long airframe

 

Do all this without derates in a light airframe and in the blink of an eye you will wonder who will be the first to remove a part of your posterior, ATC, or your Chief Pilot? Not only will things happen very rapidly, reducing your ability to think, but the intermediate level off will be far behind you. Even airlines that do not use assumed temps (SWA) STILL use derates- with good reason.

 

SO- the short answer to the original question is, "Either get a complete set of airframe RTO Charts or use TOPCAT (I do) or some performance tool."

[krazyk 157]

I use TOPCAT for an estimate/reference only. Nothing beats good old printed charts with the numbers straight from the manufacturers/employers manual.

Time consuming, yes, but rewarding in it's own way. I guess I've never trusted a dispatchers number in real life until it's close to what me and the boss on the left seat come up with.

 

After that, it's a simple reference with what the aircraft throws at you and adjustments are made as required with the latest weather and NOTAM reports. Don't know how many of you would agree with that as a proper procedure but real world flying and as a creature of habit, it's hard to let go even when in the simulator. :rolleyes:

[Chrjs 61]

A derated takeoff does not use more fuel. And I never once mentioned derated climbs either. So your accusation about my knowledge is baseless.

 

 

Quote 737.org (written by Chris Brady, Training Captain, Safety Inspector and Maintenance test pilot of rthe 737 classic and NG)

 

"Some Facts About Assumed Temperature Thrust Reduction

[...]

Strange, but true. This is because:

1. Assuming an uninterrupted climb, it will take longer to reach the more economical cruise altitude than a full thrust climb.
   
2. Engines are less efficient when not at full thrust."
   

http://www.b737.org.uk/assumedtemp.htm

[ESzczesniak 128]

Again, no magical difference between a few percentage points of thrust.

 

Actually, there is. When engine power is expressed in %, the assumption is this corresponds to % first stage (N1) compressor speed. This is not a linear relationship. Cruise thrust typically being in the mid-80's, maximum thrust 103-105% and maximum continuous thrust right about dead on 100%. This means almost the entire operating range of the engine takes place in a range of 20%. Interprating N1 speeds as a linear thrust relationship must be done with caution. As an extreme example, the A-10C's flight range is approximately 82-85% with ground idle at 70% and maximum thrust at 85%. So a 5% difference there is huge.

 

And the point mentioned about the 777 isn't a matter of a few percent. The point is that the assymetric thrust seen after an engine failure can create a yaw moment so extreme that a lightly loaded aircraft could not be controlled on the ground. Hence the need to derate and reduce this yaw moment.

 

Eric Szczesniak

[Captain Kevin 586]

Again, no magical difference between a few percentage points of thrust.

Tell that to the FAA. One of my test questions as a maintenance student is "Which statement is true regarding jet engines?" The correct answer is "At the higher engine speeds, thrust increases rapidly with small increases in RPM."

[Gregg_Seipp 565]

What do you guys use for fuel planning?  Does TOPCAT handle that?

[Flamin_Squirrel 71]

What do you guys use for fuel planning?  Does TOPCAT handle that?

 

TOPCAT doesn't do fuel, but PFPX, made by the same people, will do when it's out soon.

 

It's not simply a fuel/route planner either, it's a full blown dispatch info generator. It'll allow simmers to bring the realism up yet another notch.

[mosteen 111]

What do you guys use for fuel planning? Does TOPCAT handle that?

I use FSCalc for iOS, together with wind predictions from AS2012 my fuel planning is spot on for B737 and MD11.

[Jarkko 59]

At the moment I use FSBuild and vRoute Premium for fuel planning.

 

Before that I used my own spreadsheets or FSCommander.

[Gregg_Seipp 565]

At the moment I use FSBuild and vRoute Premium for fuel planning.

 

Seems like everyone is getting into the dispatch business.  You need both programs for fuel planning?  I was half thinking just to use the 22 lbs per mile + 5500 lbs. estimate.  I have to admit that, after just completing the second tutorial on the NGX, that I sit back and wonder how I'm going to get all the info together for a simple flight from...say...KPHX to KLAX.  For my other airplanes I can go to three or four websites and get my route.  Granted, I know that the NGX is a lot more complex but it's daunting just trying to connect the dots of everythng you need from throttles forward to rolloout...fuel...cost index...derate/performance info...flaps setting for a steep descent.  Did I forget anything?