From: todd@valinor.mythical.com (Todd Lawrence)
Newsgroups: rec.aviation.ifr
Subject: Re: RADAR REQUIRED for IAF
Keywords: Approach
Date: Mon, 23 Nov 92 00:36:00 CST
Distribution: world
Organization: (What? Organized??) - Mythical Computer Systems

stephens@access.digex.com (John Stephens) writes:

> In article <1elm19INNdiq@bigboote.WPI.EDU> tpc@wpi.WPI.EDU (Terence Pau Croch
> >
> >Looking at the NDB 29 approach chart from the NOS, it looks like the term
> >RADAR REQUIRED was ommitted for the entire approach. REVER is the only IAF
> >and a procedure turn is NA. Therefore, it seems that radar would be need
> >to insure that you could get lined up on the inbound course. The only other
> >way would be to fly around until you wound up inbound on the 290 bearing to
> >the SKR NDB. Therefore, radar is essential to the approach.
> >
> >This is only my view. Anyone please correct me if I'm in error.
> 
> I don't believe that inbound course alignment is the need for
> radar.  Two possibilities come to mind: either radar is required
> for the whole approach because this is a high traffic density area
> and the approach does not lend itself to high positional
> accuracy, or, the radar requirement was added to ensure the
> identification of REVER intersection.  I think the latter is more
> likely, based on the NOTAM wording.
> 
> Note that REVER is identifiable only by the 030 radial of BOS and
> the 111 radial of GDM.  It is possible that GDM reliability in
> this area was judged marginal, and that this is what led to the
> radar requirement.  
> 
> This is only a supposition -- does anyone have any hard facts?
> 


There could be many reasons for Radar being required for an approach, 
No published IAF (Where would you go when simply "Cleared for the 
approach", (ie a cruise clearance)? right-you have to be vectored to 
final. Also, abscense of a procedure turn. According to the AIM (HARD
Fact, it's FAA).. One of the reasons for a procedure turn is to help you 
align yourself on final approach.. If this particular approaches' 
procedure turn for some reason has become not authorized then RADAR IS 
required for final approach course alignment- How would you align 
yourself and decide when it was safe to decend from your enroute altitude 
to the Final Approach intercept altitude? (ie - NOS/JEPP profile View 
remark "REMAIN WITHIN XX MILES"), (Another reason for a procedure turn 
(In MY opinion, One of the most important..), is so we can remain within 
this PROTECTED airspace), remember we are supposed to cross the IAF at 
the last assigned altidude, Start time (So we can ENSURE we remain within 
the XX miles as specified on the profile view)...
when aligned with the outbound course, ONLY THEN do we begin our decent to the
published Proc Turn Altitude, Make our course reversal on the published 
(Some people like to call it the "Protected") side, and line ourselves up 
on the final approach Segment.. and so on.. So If there is no published 
course reversal/IAF you will Always see radar required because the 
controller is now responsible for Aligning you onto final approach and 
keeping you at a safe/protected altitude within Protected Airspace.. 
There are many other reasons for radar being required on a particular 
approach.. But in the above post the "procedure turn Not Authorized" is 
most likely the reason.. Also many folks look at the "10 Mile Ring" on an 
approach plate and assume this somehow reflects the protected airspace, 
this however is incorrect, a good example is "TALLAHASSEE COMMERCIAL, 
VOR-A", there is a 10 Mile ring depicted on the Plan View, however when 
one refers to the remark in the profile view one see's Remain within 5 
miles...), the 10 mile ring simply tells you that the objects depicted 
inside are "to Scale.."

Todd Lawrence
CFIAIMEI, ATP BE-1900 USAir Express
(opin's My Own NOT USAirs..)


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 Todd Lawrence   
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 -Maybe he just ran off the cliff, like a lemming... -mar/lod
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Organization: Carnegie Mellon, Pittsburgh, PA