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02/11/2009, 10:29 AM Morbz Joined on 06/02/2007 UK Posts 263 JAR-OPS Hello When it comes to take off factors for JAR-OPS ruling for class B aircraft, I understand the following few points for example but I have a question or two I would like to ask.  Calculations such as the following can be used: 1.   (T/O + LDG Roll) x 1.3 gives you a safety factor that you compare to the ASDA -  useful to calculate the aborted takeoff roll distance you can play with 2.   T/O distance x 1.25 gives you a figure to compare to the TORA     OR    Several other calculations can be used if your RW has a clearway/stopway for T/O if you wish to comply with JAR OPS Also there are several landing figures such as Unfactored x 1.43 to give you a figure to compare to your LDA etc etc as well as a 15% increase safety margin for landing on wet surfaces. Knowing these few points as above from JAR OPS subpart H, I was just wondering whether or not there are any contamination factors (such as the wet factor used for landing) that are used for the takeoff?   It makes sense to have a wet factor for the landing roll as this is probably the most important and most affected part of the flight by surface contamination, however surely water contamination would contribute to an extended take off run, yet I cannot find any factors to use for the T/O.  I understand there is a similar factor to the wet landing 1.15 used for Class A aircraft but surely there is one for a class B bog standard twin fixed wing?  JAR OPs quotes: (b) An operator shall ensure that the unfactored take-off distance, as specified in the Aeroplane Flight Manual does not exceed: 1. when multiplied by a factor of 1,25, the take-off run available; or 2. when stop way and/or clearway is available, the following: (i) the take-off run available; (ii) when multiplied by a factor of 1,15, the take-off distance available; and (iii) when multiplied by a factor of 1,3, the accelerate-stop distance available. (c) When showing compliance with subparagraph (b) above, an operator shall take account of the following: 1. the mass of the aeroplane at the commencement of the take-off run; 2. the pressure altitude at the aerodrome; 3. the ambient temperature at the aerodrome; 4. the runway surface condition and the type of runway surface; 5. the runway slope in the direction of take-off; and 6. Not more than 50 % of the reported head-wind component or not less than 150 % of the reported tail-wind component.   Point 4 here makes me believe there must be additional safety factors! I hope you undestand what I mean here and if not please ask further questions.  Im just trying to get my head around the performance section of my flying before I sit my CPL skills test in a few weeks time (fingers crossed).  Morbz      Report

02/11/2009, 6:37 PM Nicky Joined on 01/02/2006 Nottingham Posts 256 Re: JAR-OPS Hey Morbz,  Yeah you're right they don't even give you a factor for the wet on T/O for Class A aeroplanes, only wet grass... (at 1.30) It would make sense to include a wet paved runway factor as you said it surely increases T/O run! Good question..    Report

02/11/2009, 6:57 PM Nicky Joined on 01/02/2006 Nottingham Posts 256 Re: JAR-OPS Just been having a look around and found a circular that mentions this topic. It states "For JAR-OPS performance purposes, runways reported as WATER PATCHES or FLOODED should be considered as CONTAMINATED". Therefore Dry, Damp or Wet runways aren't considered as contaminated for T/O. Anyway there's alot more information in the document so take a look for yourself: AIC 86(P126)/07    Report

02/11/2009, 8:15 PM Morbz Joined on 06/02/2007 UK Posts 263 Re: JAR-OPS Thanks, I'll give that a good read at some point when I'm next free.  It is a strange one so if anyone else can perhaps enlighten me with their commercial knowledge that would be great! Cheers Morbz    Report

14/12/2009, 4:42 PM Anthony Tester Joined on 24/09/2007 Vienna Posts 104 Re: JAR-OPS A wet grooved runway can be considered as dry, normally there is a performance table for contamination depending on contaminant type (water, snow, slush) water equivalent depth and braking action. In my commercial experience we tend to have what are called IRT's (Individual Runway Tables) which provide us with all the data we need, mostly they are used to calculate a takeoff power redution (airbus would call it Flex) by using an assumed higher ambient air temperature which is cross refferenced with aircraft weight. Therefore it is rare that we ever calculate the TODR. FO DHC8-300 and 400 Austrian Arrows    Report

15/12/2009, 10:25 AM Morbz Joined on 06/02/2007 UK Posts 263 Re: JAR-OPS Anthony I passed my CPL skills test today first time!  Absolutly over the moon!  Found out that for takeoff the AFM has the specifics for wet runways as JAR OPS only supply factors for landing and TO on dry.  Thanks for your help though. Morbz    Report

15/12/2009, 3:26 PM Aviator|Chris Joined on 28/01/2009 EGBO / Birmingham Posts 302 Re: JAR-OPS Congratulations - Very Well Done!!! Knew you would nail it in one!    Report

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