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Author Topic: Interesting ND Depiction from KEWR  (Read 392 times)

emerydc8

  • Join date: Jun 2015
  • Location: Tucson, AZ USA
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Interesting ND Depiction from KEWR
« on: Thu, 7 Nov 2019 08:46 »
I would have thought the 220 heading/vectors line would be drawn starting from 2.3 ILS, but it looks like the conditional waypoint at 400' AGL gets in the way, or the HDG is displayed as soon as the conditional waypoint is passed, regardless of the maneuvering done prior to getting to that heading.






Newark 4 Departure RW22R: Climbing LEFT turn heading 190 to D2.3 ILSQ, then climbing RIGHT turn heading 220. MAINTAIN 2500.
« Last edit: Thu, 7 Nov 2019 08:59 by emerydc8 »

emerydc8

  • Join date: Jun 2015
  • Location: Tucson, AZ USA
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Re: Interesting ND Depiction from KEWR
« Reply #1 on: Sat, 9 Nov 2019 06:54 »
Now, from the other direction, this looks like what I would expect to see on the ND. But why the difference with the heading segment of the leg?





Newark 4 Departure RW04L: Climb heading 039 to 500, then climbing RIGHT turn heading 060 to D4.0 IEZA, then climbing LEFT turn heading 290. Cross TEB R214 WESTBOUND at or above 2500. Climb and MAINTAIN 3000.

Hardy Heinlin

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Re: Interesting ND Depiction from KEWR
« Reply #2 on: Sat, 9 Nov 2019 17:30 »
These are two conditional, floating waypoints in a row: First the path termination at 500 ft which can be anywhere, then the termination at the 4 DME arc which can be anywhere because the starting point of this path can be anywhere. The computation of the locations of such floating waypoint sequences can be a nightmare, especially if 500, for example, will be reached outside the 4 DME arc, or at a point before the arc where HDG 060° is no longer possible -- and so on. Such a constellation is like a can of worms; the can may open when one parameter is by just a hair outside the scope.

On your first photo, the start of the vectors line seems correct as it starts at the 2 DME arc (should it really be 2, not 4 DME?) but at that point -- and at that predicted fly-over radius -- it may be impossible to turn far enough to the left to heading 190° before reaching 2 DME, and thus the line to ILSQ/02 may shoot into random nirvana anywhere outside the 2 DME arc.

If you reach 420 or 500 that late, the FMC must think you're very heavy.


||-ardy

andrej

  • Join date: Apr 2012
  • Location: Bratislava, Slovakia
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Re: Interesting ND Depiction from KEWR
« Reply #3 on: Sat, 9 Nov 2019 19:28 »
Hardy,
Regarding your query in the first photo, it is 2.3NM.

Screenshot from most recent NEWARK 4 dep. chart (source: Navigraph).



EDIT: I am unable to resize the image as I am posting my Smartphone....I will do it on Monday. Sorry to all.

EDIT: fixed it already -- Hoppie
« Last edit: Sat, 9 Nov 2019 22:15 by Jeroen Hoppenbrouwers »
Andrej

emerydc8

  • Join date: Jun 2015
  • Location: Tucson, AZ USA
  • Posts: 1829
Re: Interesting ND Depiction from KEWR
« Reply #4 on: Sat, 9 Nov 2019 22:46 »
Quote
If you reach 420 or 500 that late, the FMC must think you're very heavy.

We were about 80,000 pounds under our max takeoff weight on both departures. I'm just wondering why the turn to 220 heading off RW22R doesn't start from the ILSQ D2.3 waypoint, like the turn to 290 off RW04L starts right at D4.0 IEZA. Both have conditional waypoints. The only difference I see is that on RW04L there is an at--or-above waypoint prior to the start of the last heading for vectors (TEB R214).

Quote
On your first photo, the start of the vectors line seems correct as it starts at the 2 DME arc (should it really be 2, not 4 DME?) but at that point -- and at that predicted fly-over radius -- it may be impossible to turn far enough to the left to heading 190° before reaching 2 DME, and thus the line to ILSQ/02 may shoot into random nirvana anywhere outside the 2 DME arc.

Even on the 747-200 at max takeoff weight, I have never done this departure without being fully established on the 190 heading well before reaching the D2.3 ILSQ. On this departure, there is a sound measuring device in the steeple of a church off the end of the runway, so SOP was to start the turn at 50' to avoid getting a $2500 fine.

I'm not home to check what PSX would display on these departures.

[EDIT] If you look at the LEGS pages, the departure off 22R shows a 190 heading for 0 miles, whereas the departure off 04L shows a 060 heading for 2 miles. Hardy, you may be right that if a heading is to be flown after a conditional waypoint on takeoff, followed by another turn at a specified arc distance, if the arc distance is only 2 miles (2.3 in this case), the ND will depict it as 0 miles as it does for 22R. But where the arc distance is 4 miles (as it is for 04L), the ND will depict it as 2 miles.
« Last edit: Sun, 10 Nov 2019 16:13 by emerydc8 »