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Runway behind you - a way to save time?

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Runway behind you - a way to save time?

Old 30th Jun 2009, 13:04
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<<You'll have to take my word for that because I am not going to name the venue.>>

Why on earth not? It might help people to explain things to you.

I fell about at your mention of 20 seconds roll then up to FL400!!! Apart from jet fighters and the odd clockwork mice bizjets I think I've only seen one commercial aircraft get airborne in 20 seconds and that was a Dash 7. In busy airspace not too many aircraft "launch up to FL400".
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Old 30th Jun 2009, 13:17
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Heathrow Director, I do appreciate you've pretty much seen it all, but those 738's are blessed with an enormous amount of available thrust and if a captain wants to make a point of getting a nearly empty one heavenward in double quick time then if someone like me is watching the second hand, they may indeed register a number as low as 20 seconds from application of what sounded like a goodly amount of power at one end of the runway to last rumble from wheels about halfway down. And with one as empty as ours, launching in not at all busy airspace up to FL400 is what the locos apparently do with their derring at every opportunity
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Old 30th Jun 2009, 13:23
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Slip and turn...how much of this thread are you reading and just how much are you understanding?

I also know that once I am approaching flying speeds in something weighing 60+ tonnes and which normally uses most of 3000 feet or so to land and stop reasonably, that I'd rather have that and more available just prior to V1 than something only half as convenient.

You know what?

Why would you rather have something more available than the performance calculations require?

Apparently now you have moved on from:

Part-trained/studied, but not earning my living in aviation.
to:

I also know that once I am approaching flying speeds in something weighing 60+ tonnes
That was a quick change, without actually learning anything more about the situation you first described!

the rotation point was much further down the runway than is usual and a couple of seconds or 3 earlier just before V1,
The rotation point was a couple of seconds BEFORE V1?????

You really need to read some more about aircraft performance!

the picture of the end of the runway arriving would not have been much improved.
Why on earth do you care about the picture of the end of the runway? This is not a Cessna 150 you were traveling in! Unless that picture involves a truck driving out in front of you it does NOT matter. The calculations will tell you if with the associated power and flap settings you can achieve the performance requirements for a Perf A airacrft on that runway from that intersection, NOT your perception from row 30 of how much runway is left.

I'd be interested in some Performance calculations if anyone has the will. Let's be conservative: if anyone is feeling kind enough to provide some numbers to chew on, then what might they be for say 60 tonnes, NIL wind, temperature 15 degrees, and let's say sea level with 1022hPa? Runway dry of course. Qualify it with your packs and any other niceties. Anyone?
I'd be interested too, but without an aircraft type and an airfield I think you'll find it pretty hard to get any!

Please Slip and Turn if you genuinely are training to be involved in flying aircraft take a very long hard look at the tripe you are writing, go and have a look at some threads or books about aircraft performance and see if you think it is appropriate to re-write some of your posts!

Jazzy

Last edited by JazzyKex; 30th Jun 2009 at 13:44.
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Old 30th Jun 2009, 13:32
  #24 (permalink)  
 
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Wow, this thread really shows on of the most irritating things that I know as a professional pilot. When someone takes a step in to the flightdeck after landing saying something like: "that was a bit wiggly, wasn't it?"
A pilot for a serious airline would never do an intersection takeoff if he didn't know that he could make it safely. And what u described as hesitation of backtracking/lining up it is standard procedures, since the intersection distances are calculated from a different point than where the rapid exit taxiway centerline turns off the runway. We always have to make a slight "backtrack turn" to get the distance that is calculated.
The biggest time-saving is not won at the shorter taxi, but mostly from being able to get out before inbound traffic or other take-offs.

Now im gonna have to rush to work.
My first take off for the day will most certainly be an intersection-takeoff with my B738. (It always is at this base, pretty sure I don't need 3500meters)
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Old 30th Jun 2009, 14:12
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Slip and Turn

If you are genuinely concerned about this matter, why don't you address it to the Director of Flight Safety at the airline you flew with? You would then at least be able to name the airport, the exact flight you took and you might even get a reply. I take it you also disembarked without raising your concerns to the flight crew?

Or do you simply like riling feathers by posting anonymously here?
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Old 30th Jun 2009, 14:13
  #26 (permalink)  
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JazzyKex, I am not going to engage with your lengthy dissection save for two things:
1. to say that you misunderstood my sentence that led you to believe that rotation was before V1. My poor English grammar I guess. Sorry about that.
2. to say that our exact progress down the runway as measured by me was by looking out the side window at known reference points, and the picture at the front is imagined.

You have the type, its the trusty 738. I've given you an airfield elevation - sea level more or less as makes very little difference. You don't need a name. There are no airfield related restrictions to be factored in.

If time and time again I feel brakes graunching (protesting) at the end of a landing roll on 25 at Stansted which has included use of reverse thrust on touch down, and that's apparently necessary in order to make the last fast turn off, then I can start making some assumptions can't I? I go to Google Earth and find the approximate median of the all the rubber marks at touchdown, and measure the distance between the rubber and the SR Technics fast turn off, I can hazard a guess that stopping one of these things from flying speeds with no wind to speak of uses up most of 3000 feet more often than not. Sometimes of course, it can't be done with any comfort remaining so we sail past to the end exit point.

So I am not one to unconditionally accept that if I possess Perf A calcs in my sweaty hand or programmed into my machine, QED I can leave 2300 feet behind me when I start to roll. If I notice that my wheels leave the ground with only 1800 feet of runway remaining, I might perhaps wonder if those Perf A calcs I relied upon were yer actual gospel. They might have been ... just ... if it is further a fact that another 1200 feet used post V1 to wheels off is typical. I don't know. Sounds feasible, if a bit tight.

Maybe the Performance figures do easily show that just before V1 I can indeed stop well inside my imagined/roughly estimated 3000. I don't doubt the theoretical feasibility of that either.

But my question wasn't "is it ok/legal?". I suppose the gist of my question was, to borrow a word from 11Fan's first take on the thread, "Is it prudent?"

Why did the crew of one flight out of very many similar flights decide to do something different which relied on reduced margin for errors/failures/safety with corresponding gain that could only be measured in time/economy?
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Old 30th Jun 2009, 14:21
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Couldn't this entire slanging match been avoided by just one poster pointing out that, as 99% of airlines use Reduced Thrust for Takeoff :-

(1) If the full length had been used, the thrust reduction would have been MUCH greater, emulating a Field/Obstacle limitation, and

(2) As a reduced length was used, the thrust reduction would have been MUCH less, emulating THE SAME Field/Obstacle limitation.

In short, either of the Takeoff choices would have been operating to the same safety tolerances.

Sometimes.......................

Regards,

Old Smokey
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Old 30th Jun 2009, 14:38
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Guys, we are wasting our time here. He's not listening.
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Old 30th Jun 2009, 14:38
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You would think so Old Smokey, but then the OP is well known for being an argumentative besserwisser.

The ensuing 'match' is obviously the very purpose of the thread.

Last edited by One Outsider; 30th Jun 2009 at 15:02. Reason: Replaced probably with obviously.
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Old 30th Jun 2009, 14:41
  #30 (permalink)  
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I like Old Smokey's "sometimes" although I rather think he's referring to the way that sometimes threads really do make him want to bang his head, not how sometimes the two take-off choices yield the same safety tolerances

Sometimes, you just get the feeling that the pilot is slightly lost on the ground, or in two minds ... Rainboe mocks the feeling, as if SLF can't possibly know what is grinding the cogs. I imagine it's the same feeling you get when it's not your usual chauffeur who picks you up and he dithers at how to get around the usual obstacles and jams. Whereas your normal chauffeur just gets on with it before you even dream of looking up from your broadsheet in the back and saying "Don't dither man, get on with it!" ... never been there myself of course .

Besserwisser? Now I'll have to look that up.
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Old 30th Jun 2009, 14:42
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Here we go again...

Thank you for clarifying that the rotation was after V1.

As for the rest of your post, you are still not grasping the concept that no matter how perceptive you consider yourself to be you did not know the circumstances surrounding the decision to use an intersection on the day you quote.

Why did the crew of one flight out of very many similar flights decide to do something different which relied on reduced margin for errors/failures/safety with corresponding gain that could only be measured in time/economy?
How do you conclude that margins were reduced in any way?

Did you see the performance calcs? If so were was they adhered to? Unless that is the case then I cannot see how any 'margin for error' has been reduced.


You have the type, its the trusty 738. I've given you an airfield elevation - sea level more or less as makes very little difference. You don't need a name. There are no airfield related restrictions to be factored in.
It is a little more complex than using a generic 738 on a generic airfield. If you want to find out if your crew were being negligent as you apparently think they were then we need to know FOR THAT FLIGHT the exact weights, configs, flap settings and the power settings they used and compare them to what you think they should have used! Ideally we need to see their company take off performance manual and the loadsheet...see Slip and Turn, it isn't enough to google the tyre marks unless you know which ones are yours!!!!


So I am not one to unconditionally accept that if I possess Perf A calcs in my sweaty hand or programmed into my machine, QED I can leave 2300 feet behind me when I start to roll.
So what are you going to accept? Assuming your training continues and you intend to fly a commercial aircraft which manuals are you going to choose to ignore and which to obey? If the performance manual is not prudent enough for you then I suggest you ask why JAA regulations allow their use when clearly looking out of the side window at fixed points is far more accurate.

Sorry I forgot your back seat judgment is better than the perf calcs...

I might perhaps wonder if those Perf A calcs I relied upon were yer actual gospel. They might have been ... just ... if it is further a fact that another 1200 feet used post V1 to wheels off is typical. I don't know. Sounds feasible, if a bit tight.

If time and time again I feel brakes graunching (protesting) at the end of a landing roll on 25 at Stansted which has included use of reverse thrust on touch down, and that's apparently necessary in order to make the last fast turn off, then I can start making some assumptions can't I?
Are you trying to say that because on landing in Stansted using some reverse and after hearing some brake noise you pass a turn off occasionally that equates to RTO braking performance?

Please tell me that isn't what you are trying to say...

gain that could only be measured in time/economy?
Slip and Turn, when no safety is compromised how do you intend your flight is conducted if not with regard to time/economy?

If you do get into the seat of a commercial aircraft you'll find that safety, time and economy are very much at the forefront of your daily thoughts!
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Old 30th Jun 2009, 14:48
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If time and time again I feel brakes graunching (protesting) at the end of a landing roll on 25 at Stansted
The brakes certainly would protest at such a landing not to mention the various buildings and hangars etc you would be ploughing through on your landing roll

BTW is the airport in question Edinburgh? I have seen and been in countless intersection departures from there without incident.
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Old 30th Jun 2009, 14:49
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Yes Old Smokey it probably could but clearly our friend doesn't trust the concept of Perf A and has little understanding of its use and I suspect One Outsider is closer to the truth...

Anyway it's giving me somewhere to rant while watching some very mediocre ladies tennis!
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Old 30th Jun 2009, 14:59
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Oh dear, really rocked your boat I see, JazzyKex !

I simply estimated that at least half the rubber put down at Stansted was by 738s. It was an estimate ... you know that e-word you use for all your load weights apart from the fuel I guess?

Yes if you want to make things deliberately complicated for a rough answer then by all means include some flap settings/configs/whathisnots.

My training isn't continuing, JazzyKex. I'm a "don't-wannabe". Workplace politics are bad enough on the ground without walking into a job which places you in the thick of some of the worst workplace politics, but expects you to be constantly at the top of your game with regard to safeguarding lives down the back.

Are you a wannabe, JazzyKex? Cos you seem to have a great knack of getting hold of the wrong end of various sticks. You are right about the tennis however
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Old 30th Jun 2009, 15:23
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No boat rocked Slip and Turn and no sticks grabbed by the wrong end either.

I'm not trying to make the calculations complicated...just to explain that to assume that anything was being done without prudence would require you to know exactly what the circumstances were.

As for the estimates made for loads...just assumed weights for the men and women which err on the side of safety in the same way the Perf calcs have factors of safety built in with assumptions about aircraft performance.

As has been mentioned before safety is the priority and has been built into the system of performance calculations to negate the need for second guessing the validity of the data once it has been gross error checked.

As for choosing to be a 'don't wannabe' fair enough. I can't say that I've encountered any politics in the flight deck though. We leave that on the ground and in the hands of those that prefer their perch behind a desk rather than up front where we spend more of our effort in considering the expediency of intersection takeoffs!

Here's hoping Azerenka can stop it being an all William's final....
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Old 30th Jun 2009, 17:00
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From post # 1.

Am I being unfairly critical?
Yes, as a matter of fact you are. Intersection takeoffs are done every day all over world and they are completely safe.
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Old 1st Jul 2009, 00:01
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Offending a Profession

Slip and Turn,

I think what you will find is that whilst there is no penalty in asking a question, there is certainly going to be a backlash when you make accusations of unprofessionalism with extremely limited and subjective evidence.

To assume that pilots are tired and just want to get home 5 minutes earlier by compromising safety and performing intersection takeoffs contrary to policy is absurd.

To assume professional 738 drivers are 'confused on the taxyways' simply due to taking a different non-direct route to get to the TO runway is equally absurd. Were NOTAMs in effect? Was there garden maintenance vehicles near Taxiway F? How can you tell from one side of the back of the aircraft?

Credit where credit is due mate, these pilots are highly (and completely) trained professionals operating under strict safety regulations which are first priority ALWAYS. To assume that an intersection takeoff and indirect taxi equates to a tired and confused pilot is naive and offensive.

Please feel free to ask the question you asked, but be respectful of the answer, or don't assume incompetence/unprofessionalism straight away. That's offensive.

End rant.

Matt
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Old 1st Jul 2009, 02:13
  #38 (permalink)  
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Folks, this whole stupid thread has been a trolling expediton, with a troublemaker knowing how to tweak sensibilities here.

Don't feed the troll! I don't think I have read such stupidity on this board before. It is designed to cause a hysterical reaction. Ignore.
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Old 1st Jul 2009, 10:32
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No, no, Rainboe, you can learn a lot from knobbers like this. First of all you can learn to persist in illogical arguments, despite the fact that your question has been answered by professionals. You might think those exams you took and the every-day use of Perf A calcs are important but, as you can see you're wrong. So, from Mr K.Nob you can learn how an aircraft REALLY gets airborne by counting the number of seconds (whilst seated in row down-the-back) and comparing it to how it usually feels. He's done this many times, so what would the operating crew know. What's even better, is you can also learn all about auto-brake settings. Not from the landing weight, vacating distance, turnround time versus brake temps etc but, no; now you can learn using Google Earth.

On second thought, you're right. S&T you are a tw*t. You've got your answer now piss off to some Microsoft forum and discuss how real professionals do it.
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Old 1st Jul 2009, 10:55
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If you do a search on him/her then you will see a trend of posts with a common enough link. Lots of posts on BA038, Turkish at Schipol, Ryanair depressurisation, ground collision, Coventry incident and the like. Trolling no doubt to get a rise and or research a story as Rainboe points out.
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