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MDA

Old 22nd Aug 2013, 19:57
  #61 (permalink)  

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Franzl, they are just kids playing now. No proper knowledge at all.
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Old 22nd Aug 2013, 20:47
  #62 (permalink)  
 
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aerocat and boac

I simply meant the following: sometimes the dive and drive technique allows you to see the runway and maneuver around clouds that might otherwise be in the way of a constant descent.

if there is a cloud at the mda in the exact place that the constant descent leads you to, then you don't get in.

if you get to the mda early and DO NOT LEAVE THE MDA until it is safe to do so, you might observe the runway and a way to it that the constant descent would not allow you to see.

I DO NOT, say again, DO NOT advocate leaving the MDA until the runway can be safely made. But the harsh reality of non precision approaches simply means the clouds have to be out of the way...flexibility, crew coordination, precise understanding of the particular approach, airport environment and the like all are part of the equation.

and for the record I do not steepen an approach to a runway if the runway is seen ''too late''.
I also remind you all that circling or non straight in approaches also have an MDA and even with the restrictions airlines now impose of basic vfr to circle, observations at MDA on the early side (or basic vfr equiv for certain airline ops ) aid in the approach.


oh, and just in case...sometimes, in odd situations, a non precision apch may get you in while an ILS leaves you in the cloud for the same runway...

Last edited by flarepilot; 22nd Aug 2013 at 20:53.
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Old 23rd Aug 2013, 06:25
  #63 (permalink)  
 
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Understand what you're saying, though the point of a constant descent approach is to hit the MDA on profile (ie 2w/2r on PAPI), so if you can't get in off the CDA because there is cloud on profile at the MDA then you shouldn't be getting in off the dive and drive either if, as you say, you are not leaving the MDA below or above profile.

oh, and just in case...sometimes, in odd situations, a non precision apch may get you in while an ILS leaves you in the cloud for the same runway...
Not in our company it wouldn't, unless the ILS is not aligned with the runway. The final 400 feet we have to be stable including being on runway centerline. Cloud on the ILS at the DA would mean cloud on the final approach of the NPA as well.

Last edited by AerocatS2A; 23rd Aug 2013 at 06:34.
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Old 23rd Aug 2013, 09:12
  #64 (permalink)  
 
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we have some exceptions to your company's rule.

lining up on final at at least one airport here requires maneuvering at low altitude.
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Old 23rd Aug 2013, 09:27
  #65 (permalink)  
 
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Originally Posted by Aerocat
so if you can't get in off the CDA because there is cloud on profile at the MDA then you shouldn't be getting in off the dive and drive either if, as you say, you are not leaving the MDA below or above profile.
Not quite. If on a close-to 3 profile with cloud at MDA + 20 on a CDA, you will almost always be forced into a Go Around, whereas you could be level at the MDA for a mile before and get in because you are just under the cloud, especially if the vis is OK. All you do is maintain altitude until flying into the PAPI and then descend.

Given the number of times this scenario is actually encountered, CDAs are better. No worries about bumping into/off/thru limiting steps.
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Old 23rd Aug 2013, 14:41
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thanks capn blogg

originally, these approaches were called, ''cloud breaking approaches''

I also recall at one time, apchs were based on visibility and ceiling...now of course most are just visibility.
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Old 24th Aug 2013, 00:52
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oh, by the way...some ILS approaches have higher mins than some localizer only for the same runway...interesting huh?
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Old 24th Aug 2013, 02:17
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flarepilot:

oh, by the way...some ILS approaches have higher mins than some localizer only for the same runway...interesting huh?
TERPs 101. The visibility for the ILS must be geometrically valid from DA to the threshold. Not so for NPA minimums.
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Old 24th Aug 2013, 09:38
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oh, by the way...some ILS approaches have higher mins than some localizer only for the same runway...interesting huh?
I'm interested! Please post one or tell us what approach it is so we can look on Airnav.
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Old 24th Aug 2013, 12:18
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Europe once again shows its anarchist face against UNO/ICAO system. They contest the laws, the logic, the reality of the ground's and obstacles' limits. Please don't fly out of Europe and don't transport not European passengers. (But once again what is "Europe" and which "Europe" - ICAO European region, European Union of 28 sovereign Countries, Eurozone, Benelux, Geographic zone from Atlantic to Oural? ?) Watch Europe's crazy history ! Aviation safety and travel freedom needs to have only one system based on international worldwide treaties in ICAO. Millions People died during worldwide Wars to get SUCH FREEDOM in a SAFE world.

Constant descend angle method once again shows its ideologic agressive and limited private conception.

Dive and drive method respects the actual ground's shape irregularities and is building approach procedures at minimum price with minimum descend (and not decision) altitude. Dive and drive concepts are build on experience of pilots, not on insurance rates and off-shor Banksters connected to Kings and Queens European Countries. Dive and drive method respects operational mathematical analysis rules where TWO sorts of parameters - and not only ONE - are used differently : 1. variables who state Limitations ("constraints"), and 2. adjustables variables who increase performance, wealth, optimization. In the approach design the first are mandatory couples distance/altitude (true altitude not baro dependant indicated altitude or angle), the latter are used to verify the path (tables in NPA) but are not mandatory.

I would like to refer too to the existence of the 15% rule of obstacle clearance in NPA procedures design : The captain of the F-GGED crash flew it (220 kts, 3300 FT/mn) but could not see he had to stop at 3660 FT until the FAF ar 7 NM DME to STR VOR, as the AF/ATLAS chart did not show the FAF position where altitude is mandatory. Appearant "Constant" descend angle method just ignores it.... as it decides to ignore MDA is ground- minimal.

Last edited by Jetdriver; 27th Aug 2013 at 04:11.
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Old 24th Aug 2013, 12:39
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I'm shocked too!
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Old 24th Aug 2013, 13:01
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capn blogg

check out KRNO, reno,nv usa...both ILS 34L and LOC DME 34L

look under cat a and b...loc dme has lower vis req than ILS
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Old 24th Aug 2013, 13:16
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... some ILS approaches have higher mins ...

Although not a direct comparison, an old NPA to Zurich 29 had visibility minima where it was impossible to see the runway at 'MDA' when on the approach path.
The then procedure design assumed level flight to MAP, from which if the runway was seen resulted in a 6 deg flight path.
Unfortunately it took a tragic CFIT accident to alert the authorities to this and change the procedure, and ultimately to install an ILS.
IIRC this accident also strengthen the case for EU CDA regulation and procedure review by ICAO; perhaps other authorities have yet to learn, adopt CDA, or implement the MDA concept.
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Old 24th Aug 2013, 13:25
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roulishollandais

"Millions People died during worldwide Wars to get SUCH FREEDOM in a SAFE world."

I was not aware that WW1+2 were about the right to fly NPAs in a certain way.

Thank you for enhancing my education.
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Old 24th Aug 2013, 13:38
  #75 (permalink)  
 
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Originally Posted by Flarepilot
check out KRNO, reno,nv usa...both ILS 34L and LOC DME 34L

look under cat a and b...loc dme has lower vis req than ILS
Fascinating. Thanks.
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Old 24th Aug 2013, 15:35
  #76 (permalink)  
 
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http://155.178.201.160/d-tpp/1309/00346I16R.PDF

http://155.178.201.160/d-tpp/1309/00346L16R.PDF

Lower mins, both ceiling & viz, for all cats, ABCD + additional E on the LOC, both straight-in and circling, versus the ILS.

Why would anyone fly the ILS in preference other than to avoid reading the note about glider activity? Long live the NPA.

There is an LPV with even lower mins ceiling wise, lower viz than LOC for CD, higher viz than LOC for AB.

Go figure.

http://155.178.201.160/d-tpp/1309/00346RX16R.PDF
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Old 24th Aug 2013, 16:41
  #77 (permalink)  
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I assume it is the different slope that raises the minima although that is a mighty jump to 7SM! I guess it must be the 6361' or 6219' that does for the ILS. Why put in a 3.1 ILS??
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Old 24th Aug 2013, 16:53
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True the LOC is 3.49 VDA to 55' TCH....but both the ILS & LPV are 3.10 degrees to a 63' TCH??

Identical slope & TCH and the LPV gets you ~1200' lower mins than ILS.

Terps 102?
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Old 24th Aug 2013, 17:28
  #79 (permalink)  
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Ah - didn't look at the LPV plate.....................yes, strange. Interesting too that the ILS does not refer to the MALSR, but since it appears little more than a 'cloudbreak'..........................
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Old 24th Aug 2013, 18:03
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dear capnblogg

you are welcome...and thanks for the civil conversation...so many say things are not so.

I grew up flying in nutty mountainous / special airports all over the USA...go figure.

Reno, Lake Tahoe , Truckee...all mountainous with unique stuff

unique stuff back east too.

all i'm saying is that whenever anyone says NO...well, you have exceptions somewhere.

and I could tell you stories about ...well, that would just garner someone calling me a liar and i'd rather be a flyer than a liar.

folks, you can also check certain notes about papi not being useable more than six miles out due to terrain...and I mean TERRAIN.
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