KCRQ Proposed RF Leg

[aterpster]

Attached are the existing and proposed replacement for the KCRQ RNAV Runway 24 IAP. The RNAV criteria has changed considerably since the present IAP was designed. Under the newer, existing criteria, the course changes to the KANEC IF on the OCN terminal route are "too tight" for today's criteria. Further, the restricted airspace just north and northeast of OCN VOR prevents designing the OC terminal route to go more to the northeast, thus permitting a series of TF to TF legs that would meet present criteria.

So, the FAA WSA airspace folks, who are a cooperative group, proposed an RF leg transition, which does meet present criteria. (also attached). This is an outstanding solution.

Problem is, the "other" FAA in DC believes pilots have to be akin to astronauts to fly RF legs. So, even in this world of TAA and NextGen, those Washington types continue to sit on their hands (or such) denying TAA the authorization to fly RF legs.

So, the two database providers, Jepp and Lido, will almost certainly not publish the proposed procedure, thus denying the airport it only non-RNP-AR RNAV IAP.

My organization is trying to get the FAA to publish both the present procedure and a second procedure without the OCN terminal route.

This is a prime example why pilots and pilot groups should keep a keen eye out for proposed IAP changes at airports that matter to your operations.

 

[TMetzinger]

Sigh... I don't get it. the various GPS' are as capable of providing left-right guidance on this as they are on a DME arc.

Or just publish the procedure and NOTAM the OCN route as "RNP required". Put a note on that on the chart.

 

[Fearless Tower]

So, the two database providers, Jepp and Lido, will almost certainly not publish the proposed procedure, thus denying the airport it only non-RNP-AR RNAV IAP.

Am I missing something....why would they publish the procedure if it is only a proposal and not approved?

SoCal can't assign a procedure that isn't approved.

 

[aterpster]

Sigh... I don't get it. the various GPS' are as capable of providing left-right guidance on this as they are on a DME arc.

Or just publish the procedure and NOTAM the OCN route as "RNP required". Put a note on that on the chart.

That note is at VISTA WP.

It's an issue with the database providers and the avionics manufacturers. They won't do it until the FAA authoizes TAAs to fly RF legs. Any aircraft that is presently RNP AR approved could fly this RF leg. And, perhaps a few other high-end airplanes.

 

[aterpster]

Am I missing something....why would they publish the procedure if it is only a proposal and not approved?

SoCal can't assign a procedure that isn't approved.

SoCal could assign the TRM or JLI terminal routes or provide vectors onto the IAP.

If it publishes the procedure would be approved as it does comply with the present RNAV order.

 

[John Collins]

SoCal could assign the TRM or JLI terminal routes or provide vectors onto the IAP.

If it publishes the procedure would be approved as it does comply with the present RNAV order.

Is there anything later than 8260.54A?

 

[John Collins]

That note is at VISTA WP.

It's an issue with the database providers and the avionics manufacturers. They won't do it until the FAA authoizes TAAs to fly RF legs. Any aircraft that is presently RNP AR approved could fly this RF leg. And, perhaps a few other high-end airplanes.

At least for GA, more is involved. None of the existing GA GPS units permit the use of the RF leg in their AFMS. The proposed approach is a hybrid, not fully an RNP or RNAV.

 

[aterpster]

Is there anything later than 8260.54A?

No, that is it.

 

[aterpster]

At least for GA, more is involved. None of the existing GA GPS units permit the use of the RF leg in their AFMS. The proposed approach is a hybrid, not fully an RNP or RNAV.

The approach is considered Advance RNAV, not RNP. The construction has been authorized in Order 8260.54A for quite sometime.

As to the fact RF legs are not in many TAA AFMS is inexcusable at this point in time.

It is not exactly RNP AR. That RF leg (well two actually) at CRQ has a two mile primary area each side of centerline with a 1 mile secondary each side of those areas, at least 1,000 feet of obstacle clearance in those primary areas, and a 4 mile radius of turn. An RF leg in advance RNAV cannot have a radius of less than 3 miles, and it has to end not less than 2 miles from the start of the final segment.

 

[Henning]

Okay, I openly admit I am not an IFR maven. I am IFR competent and able to operate. I don't know all the creation theory, but my question looking at the proposed is what part of this is supposed to be difficult for me to execute?

 

[aterpster]

Okay, I openly admit I am not an IFR maven. I am IFR competent and able to operate. I don't know all the creation theory, but my question looking at the proposed is what part of this is supposed to be difficult for me to execute?

It would be difficult because the procedure won't be in your database until the FAA somday lets you do RF legs.

 

[Henning]

It would be difficult because the procedure won't be in your database until the FAA somday lets you do RF legs.

Right, but you are saying they won't allow it because it's difficult, I was wondering what was supposed to be difficult.

 

[aterpster]

Right, but you are saying they won't allow it because it's difficult, I was wondering what was supposed to be difficult.

The FAA thinks it difficult not me.

 

[COFlyBoy]

Right, but you are saying they won't allow it because it's difficult, I was wondering what was supposed to be difficult.

I guess the FAA thinks you would have trouble following the CDI around the radius.

I think it would be easier than following a DME arc, since you would just continuously correct to whatever the CDI is saying.

Edit: Maybe the problem is that it would not be a standard rate turn. And us bugsmashers don't know how to do those. Only an autopilot coupled to an FMS with intertial nav can handle that!

 

[Henning]

No worries, it'd be painted on my G-500, I can fly it slick as snot if they give it to me.

 

[aterpster]

I guess the FAA thinks you would have trouble following the CDI around the radius.

I think it would be easier than following a DME arc, since you would just continuously correct to whatever the CDI is saying.

Edit: Maybe the problem is that it would not be a standard rate turn. And us bugsmashers don't know how to do those. Only an autopilot coupled to an FMS with intertial nav can handle that!

Any roll-steering autopilot will fly an RF leg quite nicely.

 

[Henning]

Any roll-steering autopilot will fly an RF leg quite nicely.

Well, if you think it requires an A/P then I understand their concern.

 

[aterpster]

Well, if you think it requires an A/P then I understand their concern.

No, I don't. But, that is the way the FAA thinks, as stated in AC90-105:

http://rgl.faa.gov/Regulatory_and_G...ircular.nsf/list/AC 90-105/$FILE/AC90-105.pdf

They believe it requires either a roll-steering autopilot or flight director. What do I believe? I believe they are full of it.

I work with RNP AR, which does require all the bellls an whistles because of the flexible and very small RNP protected areas.

But, this "Advanced" RF leg has a huge protected area. With an EHSI it can be hand-flown with ease, especially if the RF leg is on a decent map display like even a 400W or 500W.

 

[John Collins]

Although the RF leg has a large primary protected area, essentially +/- 2 NM on either side of the center radius path, it is half the size of the primary protected area for a DME arc, which is +/- 4 NM on either side of the arc. In the case of the DME arc, a CDI is not used or required as one has the distance read out to guide the pilot action. On the GNS series and later GPS units, it is true that CDI guidance along with a moving map depiction is added to assist with navigating the arc, but it is not available on a non GPS based GA aircraft. In the case of an RF leg, the radius of the turn is not charted and there isn't a radius read out nor a location of the center of the radius depicted on the chart. This means that a CDI or cross-track distance, or FD or roll steering is required to know where one is. The moving map if set to an appropriate zoom could probably be used to assist with this task, but if set to an inappropriate zoom, could easily be misleading.

I am not making a judgement regarding flying the RF leg type, but merely pointing out some considerations.

 

[aterpster]

Although the RF leg has a large primary protected area, essentially +/- 2 NM on either side of the center radius path, it is half the size of the primary protected area for a DME arc, which is +/- 4 NM on either side of the arc. In the case of the DME arc, a CDI is not used or required as one has the distance read out to guide the pilot action. On the GNS series and later GPS units, it is true that CDI guidance along with a moving map depiction is added to assist with navigating the arc, but it is not available on a non GPS based GA aircraft. In the case of an RF leg, the radius of the turn is not charted and there isn't a radius read out nor a location of the center of the radius depicted on the chart. This means that a CDI or cross-track distance, or FD or roll steering is required to know where one is. The moving map if set to an appropriate zoom could probably be used to assist with this task, but if set to an inappropriate zoom, could easily be misleading.

I am not making a judgement regarding flying the RF leg type, but merely pointing out some considerations.

The radius of the RF leg, as well as the arc center point, will show in the IAP's database.

 

[John Collins]

The radius of the RF leg, as well as the arc center point, will show in the IAP's database.

No argument, it has to be defined in the database so the navigator can calculate the arc. My point is that it isn't charted or displayed by the navigator.

 

[aterpster]

No argument, it has to be defined in the database so the navigator can calculate the arc. My point is that it isn't charted or displayed by the navigator.

It will show on the legs page to the pilot. It can be loaded and reviewed in advance. I believe that is what I said in my Post #20.

 

[John Collins]

It will show on the legs page to the pilot. It can be loaded and reviewed in advance. I believe that is what I said in my Post #20.

OK, post 20 wasn't very clear on this point. I am guessing you are referring to the flightplan page as I am not aware of a "legs page" on the GA GPS units. Maybe you are referring to some non GA equipment. Feel free to clarify.

Regardless, since none of the GA GPS units currently include the capability for RF legs (GNS480 Pilot guide does say it can support the leg, but the AFMS does not), where did you come by this understanding? Is it a part of a TSO, AC, or DO? Reference please.

 

[aterpster]

OK, post 20 wasn't very clear on this point. I am guessing you are referring to the flightplan page as I am not aware of a "legs page" on the GA GPS units. Maybe you are referring to some non GA equipment. Feel free to clarify.

Regardless, since none of the GA GPS units currently include the capability for RF legs (GNS480 Pilot guide does say it can support the leg, but the AFMS does not), where did you come by this understanding? Is it a part of a TSO, AC, or DO? Reference please.

See private response.