New Circling Minima Criteria

[TangoWhiskey]

Just read an interesting article in the December 2013 issue of IFR.

Something new you'll start seeing on approach plates, such as this RNAV (GPS) RWY 05 approach in Frederick, MD:

http://download.aopa.org/ustprocs/current/NE-3/fdk_rnav_gps_rwy_05.pdf

Notice the circling minimum line. If you saw that inverse block "C", would you know what it signifies?

 

[davidm767]

Yes,

Its actually been in the Aeronautical chart users guide since October (maybe even earlier this year) . It means that for procedures developed in late 2012 and on there were new circling maneuvering distance criteria accounting for true airspeed increase for an increase in altitudes. Essentially old CAT A-E distances were further complicated by altitudes CAT A-E (1000, 1001-3000, 3001-5000, etc).

Good one for DPE's (if they know!) to ask new instrument candidates if they know what it is and where to find it.

I find a lot of colleges do not show their students the Aeronautical Chart Users Guide, which is really unfortunate because that has ALL of the information a student really needs to understand about their charts.

 

[TangoWhiskey]

Yes,

Its actually been in the Aeronautical chart users guide since October (maybe even earlier this year).

http://aeronav.faa.gov/index.asp?xml=aeronav/applications/digital/aero_guide

 

[NoHeat]

Okay, so I looked it up in that guide, and I don't get it.

For Category A approach speeds, which is most small aircraft, this change makes no difference for any airport under 7000' MSL. And above that altitude the 'protected radius' is increased by only 0.1 NM.

So does it matter?

 

[BobThePilot]

Okay, so I looked it up in that guide, and I don't get it.

For Category A approach speeds, which is most small aircraft, this change makes no difference for any airport under 7000' MSL. And above that altitude the 'protected radius' is increased by only 0.1 NM.

So does it matter?

Yes, have to admit I don't understand why I should care?

Somebody in charge of the legends on these plates must be bored. Must have wanted this to be their legacy.

 

[flyingron]

Okay, so I looked it up in that guide, and I don't get it.

For Category A approach speeds, which is most small aircraft, this change makes no difference for any airport under 7000' MSL. And above that altitude the 'protected radius' is increased by only 0.1 NM.

So does it matter?

Look at the other Categories, substantial changes as the approach speed goes up.

 

[akpilot907]

Yes,

Its actually been in the Aeronautical chart users guide since October (maybe even earlier this year) . It means that for procedures developed in late 2012 and on there were new circling maneuvering distance criteria accounting for true airspeed increase for an increase in altitudes. Essentially old CAT A-E distances were further complicated by altitudes CAT A-E (1000, 1001-3000, 3001-5000, etc).

Good one for DPE's (if they know!) to ask new instrument candidates if they know what it is and where to find it.

I find a lot of colleges do not show their students the Aeronautical Chart Users Guide, which is really unfortunate because that has ALL of the information a student really needs to understand about their charts.

Good comeback question for the canidate to ask the DPE's (Stump em')
But in all seriousness, if you want to pass your checkride, do NOT use what I just suggested. If you wish to see the light off day again after an Oral Exam!

 

[aterpster]

Just read an interesting article in the December 2013 issue of IFR.

Something new you'll start seeing on approach plates, such as this RNAV (GPS) RWY 05 approach in Frederick, MD:

http://download.aopa.org/ustprocs/current/NE-3/fdk_rnav_gps_rwy_05.pdf

Notice the circling minimum line. If you saw that inverse block "C", would you know what it signifies?

This was announced sometime late in 2012. It's a big deal for most biz jet operators as well as airlines that do circle to land (not many of them).

The first IAPs with the new circle to land criteria were published in May of this year. This is from the FAA IAP chart legend:

 

[denverpilot]

So, they gave the kids going faster a bigger safer playground when the C exists? If I'm reading that right, makes sense to me.

 

[poadeleted20]

So, they gave the kids going faster a bigger safer playground when the C exists? If I'm reading that right, makes sense to me.

That's it. IIRC, this all has to do with an accident involving an Airbus circling to land at high DA and hitting something just outside the CTL maneuvering area.

 

[RussR]

Notice also, that the side effect of the increased radii is that the MDA in many cases will go up, sometimes significantly, as more obstacles are brought into the circling area.

 

[aterpster]

Notice also, that the side effect of the increased radii is that the MDA in many cases will go up, sometimes significantly, as more obstacles are brought into the circling area.

That happen hasn't to much extent thus far. CTL sector exclusion has worked fairly well at difficult locations thus far.

KAEJ, Buena Vista, Colorado, amends on the 12th. The airport sits at almost 8,000 feet, msl, with high terrain around. CTL is limited to the west of the runway.

The new criteria resulted in the following radii for construction of the CTL maneuvering area:

CAT A: 1.38 NM
CAT B: 1.97 NM
CATC: 3.12 NM
CAT D: 4.38 NM (D isn't published but the calculation was nonetheless made.)
CLT MDA is 9980 for A, B, and C. The obstacles permit lower CTL for A and B. But, they chose to use the CAT C controlling obstacle for all three categories. That doesn't make sense.

It presently is 9540.

Edit: I looked again, it is 9980 because that is the non-climb gradient LNAV MDA.