Climb gradient requirement on SID
Join Date: Mar 2011
Location: engineer at large
Posts: 1,409
Likes: 0
Received 0 Likes
on
0 Posts
terpster,
I think it is also important to show how the obstacles and terrain are calculated for the procedure design, as well as the design parameters.
Terrain data will have several additives. There will be an automatic add to the elevations of one contour interval, the a canopy add of usually 100 feet for trees.
Obstacle data provided will have accuracy codes per obstacle that must be accounted for. As an example, a wind turbine will typically have a 5E code, which means you have a circle 500' around the point and add 125 feet to the recorded elevation. (iterations around obstacles with different accuracy codes is a pleasure, as well as determining shielding and time of exposure)
For the aircraft, the design will use the max high recorded temperature for that airport, as well as the max low.
Aircraft will use MTOW with all bleeds on, and actual engine parameters, or the worst case in the fleet the procedure is designed for.
Very, very seldom has there been a design that works for both Boeing and Airbus aircraft...
The performance profile for the ac given the above parameters is then used in the procedure path, with additional additives for turns.
Design also assumes that the ac will be crossing the runway end at 35 feet.
Then its up to the people back at Company, to load the ac accordingly, with the real time parameters, and start limiting wt with temp.
When you add up all of these parameters, it becomes easier to understand why there are very few EO procedures in anyones database, and why the procedures are expensive to design.
I think it is also important to show how the obstacles and terrain are calculated for the procedure design, as well as the design parameters.
Terrain data will have several additives. There will be an automatic add to the elevations of one contour interval, the a canopy add of usually 100 feet for trees.
Obstacle data provided will have accuracy codes per obstacle that must be accounted for. As an example, a wind turbine will typically have a 5E code, which means you have a circle 500' around the point and add 125 feet to the recorded elevation. (iterations around obstacles with different accuracy codes is a pleasure, as well as determining shielding and time of exposure)
For the aircraft, the design will use the max high recorded temperature for that airport, as well as the max low.
Aircraft will use MTOW with all bleeds on, and actual engine parameters, or the worst case in the fleet the procedure is designed for.
Very, very seldom has there been a design that works for both Boeing and Airbus aircraft...
The performance profile for the ac given the above parameters is then used in the procedure path, with additional additives for turns.
Design also assumes that the ac will be crossing the runway end at 35 feet.
Then its up to the people back at Company, to load the ac accordingly, with the real time parameters, and start limiting wt with temp.
When you add up all of these parameters, it becomes easier to understand why there are very few EO procedures in anyones database, and why the procedures are expensive to design.
Last edited by FlightPathOBN; 9th May 2013 at 15:39.
Join Date: Mar 2011
Location: engineer at large
Posts: 1,409
Likes: 0
Received 0 Likes
on
0 Posts
ooops, forgot to mention that every 56 days, you have to re-run the analysis for any updated obstacles, then
just prior to the AIRAC cycle, you get a build from all of the navdatabase providers to verify they have the coded procedure correct (which somehow, they do manage to screw up between cycles)
you must monitor each airport there is a procedure the NOTAM's 24/7 for obstacles that would affect the procedure (since it is not public) The write the NOTAM yourself to send out to everyone affected.
just prior to the AIRAC cycle, you get a build from all of the navdatabase providers to verify they have the coded procedure correct (which somehow, they do manage to screw up between cycles)
you must monitor each airport there is a procedure the NOTAM's 24/7 for obstacles that would affect the procedure (since it is not public) The write the NOTAM yourself to send out to everyone affected.
Join Date: Jun 2009
Location: switzerland
Age: 69
Posts: 21
Likes: 0
Received 0 Likes
on
0 Posts
>7% up to 1700ft
departure 31 sez with right turn before hills.
know of a company using thrust reduction and acceleration at 800ft for a while and this is what a first officer told me to have happened to him three times in a row:
before right turn had a hard warning from egpws to pull up...
so even never flying below the 7% extension from runway end is not allways enough for some aircraft with "look ahead - but never around a planned corner - feature", when during acceleration the fms derived path is below required and to stay on safe side most of the time I follow the "sabenaboy"-method and delay acceleration all the way but sometimes when sure gradient is NOT due obstacle and limit goes up a lot (dxb up to 8000ft towards west until some time ago) I use flight path vector during clean up even if gradient is only 5% or 3degrees just to show to my colleague that his method (disregard) is wrong.
however as allways using not trained methods has downsides and this happened to me in athens with 7% to 7000ft: speed sneaking up with 3 to 4 kts per 10 seconds as shown by speed trend but crossed "f"-speed anyway.
good solution: increase angle even more and wait for the 7000ft.
my not so good solution: retract flaps and see minimum selectable speed "overtaking actual speed"...
know of a company using thrust reduction and acceleration at 800ft for a while and this is what a first officer told me to have happened to him three times in a row:
before right turn had a hard warning from egpws to pull up...
so even never flying below the 7% extension from runway end is not allways enough for some aircraft with "look ahead - but never around a planned corner - feature", when during acceleration the fms derived path is below required and to stay on safe side most of the time I follow the "sabenaboy"-method and delay acceleration all the way but sometimes when sure gradient is NOT due obstacle and limit goes up a lot (dxb up to 8000ft towards west until some time ago) I use flight path vector during clean up even if gradient is only 5% or 3degrees just to show to my colleague that his method (disregard) is wrong.
however as allways using not trained methods has downsides and this happened to me in athens with 7% to 7000ft: speed sneaking up with 3 to 4 kts per 10 seconds as shown by speed trend but crossed "f"-speed anyway.
good solution: increase angle even more and wait for the 7000ft.
my not so good solution: retract flaps and see minimum selectable speed "overtaking actual speed"...
Join Date: Jun 2004
Location: Australia
Posts: 1,843
Likes: 0
Received 0 Likes
on
0 Posts
For ANY aircraft fitted with Flight Path Angle / Flight Path Vector indication (or "The bird" on your A320), multiply the Climb (or descent) gradient in % by 0.6 to convert to degrees. The FPA/FPV indicates (or is selectable) in degrees. For your 7% gradient, 7 X 0.6 = 4.2 degrees FPA/FPV. A piece of cake and dead accurate.
Regards,
Old Smokey
Regards,
Old Smokey
Join Date: Apr 2012
Location: planet earth
Age: 59
Posts: 48
Likes: 0
Received 0 Likes
on
0 Posts
Old Smokey,
Your reply is missing the point.
The original poster wants to know how he can ascertain, before departure, that he will be able to respect the required climb gradient.
Telling him how he can see his climb angle (or gradient) at any given time, is not really helpful)
Your reply is missing the point.
The original poster wants to know how he can ascertain, before departure, that he will be able to respect the required climb gradient.
Telling him how he can see his climb angle (or gradient) at any given time, is not really helpful)
Per Ardua ad Astraeus
Join Date: Mar 2000
Location: UK
Posts: 18,579
Likes: 0
Received 0 Likes
on
0 Posts
Cagedh - you do the venerable Old Smokey a disservice! He is merely responding to all the other irrelevant twaddle on here about achieved climb gradient.
It was established very early on that IFLY has no way of determining whether his/her potential climb gradient in his airline operations is suffcicient.
It was established very early on that IFLY has no way of determining whether his/her potential climb gradient in his airline operations is suffcicient.
