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Runway behind you.

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Runway behind you.

Old 9th Aug 2009, 02:42
  #41 (permalink)  
 
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Some views cite the need for airmanship and the judgment within that when considering an intersection departure. This will involve assessing risk in the options.
Nothing is risk free; a takeoff on a dry runway using the minimum required distance is of ‘low’ risk and thus is acceptable (to the industry via regulation) for normal operations. A similar takeoff on a wet runway has more risk – reduced height over the end with an engine failure, or greater probability of an overrun during an RTO, but this increased risk is also accepted by industry (regulation), perhaps partly balanced by the likely lower exposure to a combination of critical conditions (wet and engine failure).

There may be additional risk due to the poor condition of the runway – how much rubber/paint is there on the stop end, is the runway grooved, what’s the width, what’s the overrun like.
This is where airmanship can provide a balancing view of the overall risk, but this depends on the way in which humans think about risk. There is also risk in other human activity - errors, your own or from other sources.

Unfortunately, many pilots don’t think about these aspects; not because they can’t, but due to a lack of knowledge about the risk adjusting factors or the size of the risk. This shortfall could be due to not seeing (perceiving) the factors, or even not looking for any.
In addition to basic knowledge, there is need for specialist knowledge; how to judge the risk in these factors; some may not apply on a wet runway, others involve risk at all times.

We are creatures of the present, more often failing to look ahead. We tend to rush, take short cuts, allow bias of what other people think/do effect our judgment, or we just forget – being unable to recall what might be important in a ‘routine’ situation.
IMHO those who believe in the fallibility of the human, and likelihood of personal error, would choose to have the additional the margin of a full length runway … but then again we tend to choose the option with most to gain – save time, save fuel.
I wonder if management would agree if they balance an intersection departure against the cost of an ‘avoidable’ serious incident. Instead of waiting for the hindsight which comes with an incident, use foresight to provide guidance or procedural ruling (company or personal SOP), e.g. no flex with wet intersection departure – balance the risk as well as balance the runway length.

For ATC’ers; what is the additional risk in intersection departures? Runway incursion more likely, differing points of focus for departing aircraft, additional calls (or chat) for ground movements. Everywhere there is change, there is opportunity for error.
And does any of this influence the pilot;- to rush, forget checks, or fail to look out?

IMHO, whether you are a PPL or a commercial pilot, the question is not about looking for the reasons for conducting intersection departures, it is about the justification for your decision – should you be making an intersection departure in these circumstances – even after considering the context of the current situation at some future point.
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Old 9th Aug 2009, 13:15
  #42 (permalink)  
 
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I get irritated reading this! The emirates a345 would still have tailstriked if they would have taken the whole runway, they had misscalculated the loadsheet, hadnt they?
And of course, runway behind you is useless, but runway u wont use in front of u is just as useless. I will always be able to stop before V1 and to continue the takeoff after V1, no matter how much runway i have left behind.
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Old 9th Aug 2009, 17:15
  #43 (permalink)  
 
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V1 is a speed not a distance.

You should be able to stop before V1 as long as you have calculated V1 correctly for the weight and similarly you should be able to continue the takeoff after V1, if you can accelerate to Vr in the runway remaining.
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Old 9th Aug 2009, 17:57
  #44 (permalink)  
 
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<<For ATC’ers; what is the additional risk in intersection departures? >>

I never saw any problems and I did it for 22 years at Heathrow where we used intersection departures a great deal.. I expect they still do. Properly trained controllers and pilots know what they are at..
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Old 9th Aug 2009, 18:17
  #45 (permalink)  
 
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Agreed.

I used to love the Block 16 departures from B12..you get a prize for guessing the reg of our little green Jumbalino that did that quite often.....how the CC got the cabin ready so quickly was beyond me.

Nothing wrong with an expeditious intersection departure, but to be fair, choosing it if a full length is nearly as quick is marginal..though I did that this morning to be fair.

Ho hum.
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Old 9th Aug 2009, 19:47
  #46 (permalink)  
 
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For ATC’ers; what is the additional risk in intersection departures?
The hazard was exemplified by the Shorts 330 collision at CDG in May 2000. But not every hazard brings an unacceptable risk.

There's a considerable difference in risk management strategy between aircraft designed and operated to be robust to an engine failure at any moment of the flight, and the less capable aircraft that the OP is likely to be flying. Ironically perhaps, there's a greater potential benefit in taking the whole of a 3500 m runway in a Piper Cherokee than in a Boeing 737, as the likelihood of using the last 100 m of it in an emergency is greater.
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Old 9th Aug 2009, 21:03
  #47 (permalink)  
 
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Jesper,
What I find irritating is someone saying they can ALWAYS stop before V1 and ALWAYS continue after V1. If you fly large aircraft, have your next sim instructor give you an engine in reverse at V1, or complete airspeed loss, or a host of other problems. I'd be glad to make you eat those words and introduce you to a little humility!
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Old 9th Aug 2009, 21:18
  #48 (permalink)  
 
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Jesper, an irritated mind might fail to use an opportunity to think about the issues. What is the link between a tail scrape (for what ever reason) and full length / intersection departure?

Heathrow Director, LHR may be special (IMHO exceptional - plaudits), but as you well realize the absence problems is not absence of risk. LHR risk management may have been able to ensure the highest standard of controllers and assistants, but not necessarily ensure the same for all of the visiting pilots.

Dash&thump, I also assume that you realize that an intersection departure on a non limiting runway is not the same issue as for one in limiting conditions. An intersection London HR might be OK, but even in your ‘Jumbalino’, an intersection departure at London CY might not be so sensible.

The point of post #41 was to encourage pilots/controllers to think about the decision to accept / reject an intersection departure and state (openly or to themselves) their justification. Many posts in this forum focus on the conclusions of thinking, whereas stating the justification could help others understand a point of view.
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Old 10th Aug 2009, 08:40
  #49 (permalink)  
 
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I think you have to be careful not to get too fixated on extremely improbable events, such as being unable to fly at V1. If that scenario is a big worry, then ETOPS is unthinkable! As others have pointed out, if you're happy to go from a wet/contaminated runway with the reduced margins involved (a reasonably well-used procedure), why should the far, far lower risk of needing a lot more runway than calculated be an issue?

For me, if an intersection departure saves time or taxi distance then I'll do it. As a consequence, I'm putting less energy into the brakes and tyres which is a safety plus. There are also many reasons why I'll take full length, such as contamination, MEL items, possible windshear, etc. I always have the option of not going if I don't like what I see, too.

IMHO, if you're worried about needing extra concrete post-V1, then you should spend a bit longer assessing the prevailing conditions, the serviceability of your aircraft and be *really* careful when you do your performance calculations. This is probably far better insurance than anything else.
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Old 12th Aug 2009, 04:29
  #50 (permalink)  
 
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I will always be able to stop before V1 and to continue the takeoff after V1, no matter how much runway i have left behind.
Oooh, no, sir, very wrong. MU3001A has got it more...err, "correctly worded" you should. Emphasize "should".

You wouldn't be so sure of that statement if you ever flied a full pax MD-83 (that's 152 in BC config), with around 15K pounds of fuel, plus some cargo, out of a 8360ft AMSL runway that is around 13000ft long.

V1 is OVER 140KTS, by the time you are rotating you are already in the last 3000ft of runway; plus if there's anything bad about the MD-80 series is their brake efficiency. RTO 1 knot below V1, you "will always be able to stop before V1", you say? Me thinks you'll be using the cow ranch (or the street and then the buildings) further down the runway as means of stopping.
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Old 23rd Aug 2009, 09:34
  #51 (permalink)  
 
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Hmmm...i'm quite sure all the experienced pilots know what they're on about doing this day in day out..however no matter how you justify it cost and so on regardless of your calculations you can't factor in all possible scenarios or acts of nature,surely it's preferable to give your self all available options in the 1/10,000 remote possibility of a serious problem.
Intersection takeof,.wet rny, xwind near limits, humid conditions, aircraft near mtow and just for kicks a shed load of geese in your engines right at v1 ......fr in rome springs to mind...

Personally i would opt for a straight ahead landing AND FAST....many aircraft have been lost following the ole chestnut "take it into the air sort out the problem and land " boL*o*ks to that.......you hardly have time to assess what the problem is ..bet you wished you had another 3000 ahead...................

It's amazing how company ops will choose to erode god given safety margins to increase profit,intersection takeoffs,reduced thrust noise abatement procedures at near mtow etc.etc...

Obviously talk is cheap and like it or not these procedures are here to stay but personally i like to think given the option most pilots would choose to have all options open.i know i would
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Old 23rd Aug 2009, 19:17
  #52 (permalink)  
 
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...many aircraft have been lost following the ole chestnut "take it into the air sort out the problem and land"...
Any notable examples of the above, references and/or links? I say this because I know of many accidents caused by post-V1 rejects but very few where the outcome would have been improved by an attempted stop. The statistics appear to be very much against you in this scenario.

Taking the recent accident at MEL, I don't think things would have been radically improved if they'd aborted when they realised something was wrong (about 600m from the end of the runway). The report on the AMS overrun reveals that the P1 *briefed* about a >V1 reject, then performed one on an aircraft that was perfectly capable of flight, destroying it in the process.

...I like to think given the option most pilots would choose to have all options open.
Oh yes. We like options. However, experience has shown that exercising this particular option almost always results in a poor outcome. There's nothing to stop Captain X making this decision if he thinks that it's the safer option than continuing with the takeoff. All I can say is he'll need to hire a bloody good legal team if it goes wrong...
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Old 23rd Aug 2009, 20:27
  #53 (permalink)  
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paweas,
Personally i would opt for a straight ahead landing AND FAST
You're a student atpl. You might think you know everything at this stage, but this is a professional pilot forum, and you, who actually have no experience, are here peddling stupid information and advice without making clear your inexperience? I suggest you remove that utterly daft posting!
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Old 25th Aug 2009, 17:26
  #54 (permalink)  
 
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Hey guys. Just to add a little humor.

For a pilot 3 things are never too much:

-Fuel
-Rwy leght available
-Women

Speed and altitude is life

Enjoy your flying.
Cheers
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Old 25th Aug 2009, 17:37
  #55 (permalink)  
 
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For a pilot 3 things are never too much:

-Fuel
Unless you are on fire.

Back to the topic, it chills me to the bone that people like paweas peddle this nonsense. I have just over 500 hours on the B757 and know that I still know very little. How does a student ATPL feel able to post stuff like this?
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Old 26th Aug 2009, 00:13
  #56 (permalink)  
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I suggest you remove that utterly daft posting!

How does a student ATPL feel able to post stuff like this?

A couple of thoughts -

(a) doesn't matter what the field of activity, the oft-observed progress sequence is along the lines of

- apprehension
- overconfidence even to the point of gross overconfidence
- self doubt (after frightening oneself with the umpteenth near death experience)
- caution and adherence to SOP
- (for some) back (towards) overconfidence
- (for others) continued reflection and caution

- the second point usually arrives for the new pilot either during his initial training or shortly thereafter.
- the latter two points constitutes the old-bold problem.

(b) one of the values of Tech Log is that the brashness of youth (or new chum ignorance) can be challenged by the wisdom of age (and experience) and, perhaps on occasion, the new chum might just learn a little along the way to his/her own enlightened development.

From my own experience, I started off knowing it all (like many) and progressively have had that view knocked out of me by a great many folk who did, indeed, know far more than I.

In fact, I reckon that, by the time I get around to dying ... I'll probably have come to realise that I know just about naught about anything at all ?
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Old 31st Aug 2009, 18:09
  #57 (permalink)  
 
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In my own words; ALL pilots [myself definitely NOT excepted] occasionally talk lots of Horse Hooey. that's why we come here to learn from one another. the reason I even have my few post is because I read A good deal JT your Techlog makes me Fat and blind

PA

Last edited by Pugilistic Animus; 9th Sep 2009 at 05:06. Reason: I always write definately---bah!!!
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