Protected airspace

[Sea King]

All,

this is question I've come across recently. Please answer it, by using a verifiable reference (FAR/AIM, Instrument Procedures Handbook, etc.). Here it goes:

Regardless of approach category/speed, all aircraft must remain within 4NM of XXXXX (IF/IAF for a GPS Approach) to ensure the aircraft stays within protected airspace.

True or False?

 

[innovator152]

victor airways and dme arcs are 4nm wide either side. not sure of gps... other than enroute 5nm, terminal 1nm, approach .3nm required navigational performance is standard.

 

[Sea King]

uhm...I think I figured it out...the question refers to the IAF, and on the approach chart there is a hold-in-lieu of Procedure Turn.
I think the question is worded in a weird way, but bottom line, I think they are asking within how many NM from the fix (IAF) am I protected during the racetrack pattern.
Well, there are no notes in the profile view of the approach that talk about distance (the usual stay within 10NM). The only piece of info given in the profile view is "1 min".

Now, AIM 5-4-9-3 states that "When the approach procedure involves a procedure turn, a maximum speed of no greater than 200kts (IAS) should be observed...[regardless of approach category/speed]..."

200kts * 1min= 3.33NM

So 3.33NM is the protected airspace in this instance.

So, since the question is talking about 4NM, I'm gonna go w/ False...

 

[Landis]

Don't forget wind. I believe the instructions for creating a hold include 50 knots of wind at 4,000MSL and go up from there.

The approach plate in question, and the exact question, might help.

 

[mshunter]

victor airways and dme arcs are 4nm wide either side. not sure of gps... other than enroute 5nm, terminal 1nm, approach .3nm required navigational performance is standard.

Aren't those RNP levels? I thought GPS enroute required 2NM for some reason. But now that I think about it, I could be confusing it with a RAIM cert'ed GPS.

 

[DirectApproach]

For a GNSS IAF/IF, I'll refer you to FAA Doc's 8260.3 "TERPS" and 8260.54A. The newer RNAV .54A approach design criteria is, as I understand it, in transition and not yet fully implemented.

The protected airspace in the initial segment, and the starting width of the intermediate, is 2nm either side of the centerline for the primary protection areas, and then another 1nm either side of that for the secondary protection areas.

After the IF the width starts to taper. The resulting widths are different in the "old" 8260.3 and new 8260.54A, and also depends on what type of approach you are doing i.e. LNAV - LNAV/VNAV - LP - LPV..

These docs are generally available at: http://www.faa.gov/about/office_org...s/afs/afs400/afs420/policies_guidance/orders/

www.directapproach.ca