Comments on: Parallel approaches http://www.foraviators.info/parallel-approaches Fri, 03 Feb 2012 08:45:03 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: admin http://www.foraviators.info/parallel-approaches/comment-page-1#comment-6577 admin Mon, 08 Mar 2010 16:07:46 +0000 http://www.foraviators.info/parallel-approaches#comment-6577 <p>>Frankfurt (EDDF) gives separations to the previous aircraft even if this <br /> >one is for the alternate RWY. This is quite understandable since the <br /> >lateral distance between both RWYs is much smaller then in Paris. <br /> >I'd like to know now what ICAO states about parallel approaches. What is <br /> >the minimum lateral distance between the RWYs, that the approaches can be <br /> >considered as independent separation wise? <br /> <br />Your observation is correct -- separation for parallel approaches is primarily <br /> dependent upon the distance between the runways.  There is another factor that <br /> is considered, however -- the equipment and personnel available at the <br /> controller's end.  What I'm about to write is how it's done in the USA, which <br /> is about 90% compliant with ICAO on most things.  However, in this case, I'm <br /> not sure exactly what the ICAO standards are, but I imagine that although the <br /> numbers might be different, the ideas are probably the same. <br /> </p><p>The first major criteria is "final monitors".  Additional controllers must be <br /> plugged into a monitor position, one for each final which is being run <br /> parallel to another less than three miles away.  These controllers don't <br /> actually "work" airplanes.  If everything goes perfectly, they'll just sit <br /> there and never talk to a soul.  However, should one aircraft stray too far <br /> from the approach course, the monitor controllers initiate instructions which <br /> assist the aircraft back to the courseline.  If the aircraft strays too far, <br /> the affected monitors issue instructions to parallel aircraft which build and <br /> ensure separation (they take airplanes off the approach).  Without monitors, <br /> finals less than three miles apart can't be run independently of each other. <br /> </p><p>"Monitors" also require finals to be established on the final approach course <br /> WELL outside of the FAF.  Sometimes monitors are not used because the <br /> controllers don't want to take aircraft out that far. <br /> </p><p>Another major factor is the update rate of the ASR.  Conventional ASR's update <br /> something like once every four seconds.  "Quick-look" radars, like the one <br /> used at KRDU, can update once every second or even faster.  Monitors are still <br /> required to run simultaneous parallel approaches, but the distance between the <br /> finals can be reduced. <br /> </p><p>As for the distance required, 4300 feet between parallel runways is required <br /> for conventional monitors.  Quick-look radar reduces this separation -- I <br /> believe the figure is as little as 2500 feet between parallel runways, but I'm <br /> not sure. 2500 feet is the minimum for reduced separation on parallel finals <br /> (1.5 or 2 miles instead of 3). <br /> </p><p>SR - ILM <br /> </p> >Frankfurt (EDDF) gives separations to the previous aircraft even if this
>one is for the alternate RWY. This is quite understandable since the
>lateral distance between both RWYs is much smaller then in Paris.
>I’d like to know now what ICAO states about parallel approaches. What is
>the minimum lateral distance between the RWYs, that the approaches can be
>considered as independent separation wise?

Your observation is correct — separation for parallel approaches is primarily
dependent upon the distance between the runways.  There is another factor that
is considered, however — the equipment and personnel available at the
controller’s end.  What I’m about to write is how it’s done in the USA, which
is about 90% compliant with ICAO on most things.  However, in this case, I’m
not sure exactly what the ICAO standards are, but I imagine that although the
numbers might be different, the ideas are probably the same.

The first major criteria is "final monitors".  Additional controllers must be
plugged into a monitor position, one for each final which is being run
parallel to another less than three miles away.  These controllers don’t
actually "work" airplanes.  If everything goes perfectly, they’ll just sit
there and never talk to a soul.  However, should one aircraft stray too far
from the approach course, the monitor controllers initiate instructions which
assist the aircraft back to the courseline.  If the aircraft strays too far,
the affected monitors issue instructions to parallel aircraft which build and
ensure separation (they take airplanes off the approach).  Without monitors,
finals less than three miles apart can’t be run independently of each other.

"Monitors" also require finals to be established on the final approach course
WELL outside of the FAF.  Sometimes monitors are not used because the
controllers don’t want to take aircraft out that far.

Another major factor is the update rate of the ASR.  Conventional ASR’s update
something like once every four seconds.  "Quick-look" radars, like the one
used at KRDU, can update once every second or even faster.  Monitors are still
required to run simultaneous parallel approaches, but the distance between the
finals can be reduced.

As for the distance required, 4300 feet between parallel runways is required
for conventional monitors.  Quick-look radar reduces this separation — I
believe the figure is as little as 2500 feet between parallel runways, but I’m
not sure. 2500 feet is the minimum for reduced separation on parallel finals
(1.5 or 2 miles instead of 3).

SR – ILM

]]>