AC90-100, rnav sids and stars / rnav approach ISSUE

Calvin and Hobbs Meter

Calvin and Hobbs Meter

Well-Known Member
If a FMS is not eligible to fly RNAV SID/STAR/ODP's per AC90-100a, and the subsequent "AC90-100a compliance table", but they are eligible to fly RNAV routes (Q and T routes), can that FMS be used to fly rnav (gps) approaches? E.g. the FMS is RNAV 2 but not RNAV 1 compliant.

Put another way, is there a reg or AC, that I can be pointed to, that lists the requirements for RNAV instrument approaches (specifically stating RNAV 1 is required to shoot an approach). AC90-100a only discusses terminal and en route area navigation (RNAV) operations, but not standard instrument approach procedures.

I'd say the answer is "no" you can't shoot an approach if your box is not RNAV 1 approved, but would like a reference to point to that I can show to others.

Thanks
 
I would have to dig into my books and such. I believe what you are looking for lies within the operating manual of the FMS. The ACs dealing with SID/STARS etc are more about the ability of the FMS to pull a procedure up by name than the accuracy of the unit.

FWIW my Collins 850 FMC can do GPS LNAV approaches. No Q routes (per ops specs) and no RNAV SID/STARS
 
The GNS-XIS in the Brasilia is filed as "RNVE99" in the ICAO equipment block...and is approach capable.
 
This information should either be in the AFM or the AFM supplement for the FMS in question. Although your logic is sound concerning 90-100, it may not be correct. RNAV 1/2 approval is just that - a specific FAA approval (has nothing to do with actual capability). Most new AFMs make reference to the following approvals:

- RNAV 1/RNAV 2
- RNP .30
- PRNAV (RNP 1 in Europe - requires an LOA/OpsSpec)
- BRNAV (RNP 5 in Europe)
- LPV (SBAS Capability)
- RNP 10 (Requires an LOA/OpsSpec)

The reason I mention this is to show the complete lack of standardization on behalf of the authorities. Performance Based Navigation needs to align all these terms to RNP XX.XX, getting rid of all these proprietary names (PRNAV, RNAV 1).

Another reference would be FAA 8400.13. There is mention in there of "supplementary navigation," which specifically addresses using an FMS to execute an "overlay" procedure.

Good luck! This can be quite an adventure with older equipment!
 
Autothrust Blue said:
The GNS-XIS in the Brasilia is filed as "RNVE99" in the ICAO equipment block...and is approach capable.
Click to expand...

That's actually the unit in question.

C150J said:
Although your logic is sound concerning 90-100, it may not be correct.
Click to expand...

I'm more so trying to go against my logic on this one, by saying "no we can't do it", because we do it every day with that unit. I know she (GNS-XLS) can shoot rnav approaches, being that that's what we are trained in, and the AFM includes the fact that we can do so. But I also know the unit can shoot SIDS/STARS/ODP's... but we can't accept them because "she's not good enough".

What got me started was my thinking, "If I can shoot a GPS approach to mins, explain to me why I can't accept a arrival route. Well because AC90-100a says I can't. Ok, well where is the compliance list/AC for what units can shoot approaches then?"

Essentially, the best I can gather is that aircraft are packed tighter together during the terminal arrival process (over a mile apart or so, thus the RNP1 requirement), v.s. a greater horizontal separation during the approach/missed segments.


Thanks again
 
Per ICAO guideline:

"For clarification, RNAV and RNP systems are similar, but they are not the same.The main difference between the two is therequirement for on-board performance monitoring and alerting.RNP requires on-board navigation performance monitoring and alerting, and requires a letter of authorization from the FAA (or controlling agency) RNAV does not have on-board performance monitoring and alerting requirements and does not require a letter of authorization from the FAA.Most GA aircraft with GPS capability for enroute navigation (but not RNAV SIDs & STARs) would be RNAV 5 GNSS and RNAV 2 GNSS."
 
That's a very interesting/possibly misleading statement from ICAO. RNAV 1/2 procedures requires OpsSpecs in the 135 world. To assert that a GA FMS system qualifies as RNAV 5 or RNAV 2 is a huge assumption, most of which is based on bureaucratic approvals.

For example, most WAAS-equipped GA planes with FDE/Alerting have positional uncertainties of less than 20 feet and protection layers (the basis of RNP) of less than 60 feet.

All that being said, it is the OEM's responsibility to establish equipment approvals and furnish that information to operators. It is then the operator's responsibility to determine what operational approvals must be sought to actually use the equipment.

I feel your pain on this stuff - it's a mixing of terms that needs to stop. In my opinion, everything should be an RNP level and these PRNAV/BRNAV/RNAV 1/ RNAV 2 need to be eliminated. Therefore, only one LOA/OpsSpec needs to be issued - the "tightest" RNP you're authorized to execute. If you're RNP 0.1, guess what?You can execute any procedure requiring a higher RNP.
 
I do not know if it is true or not but I was told the reason that most of the XLS’s were not approved for RNAV arrivals and departures was that they had no way to include some of the fixes. Take a look at the Jake arrival into TEB. There are 3 fixes off to the left of the arrival that are not part of normal arrival. They are also not in the arrival database of most XLS’s. They are in the main database just not in the arrival database.

Now go back to the AC 90-100a and you will notice that the bottom two XLS’s are approved for the sids and stars. I know that Honeywell was offering an upgrade or exchange program to the newer unites but do not know if they are still doing it. If I remember right the mod was around 20K each a few years ago.

I do not think it had anything to do with the navigational performance of the units.
 
I heard somewhere that Honeywell wasn't servicing the XLS anymore, and that if our box broke down we would have no choice but to replace it. I've never actually seen that notice myself though. If true, I need to convince a line guy that our lav port is located in the FMS, and that it needs to be topped off with some blue juice.

We have also found that most airports with runway lengths below 5,000 ft are not stored in the box. Meaning, we can only go in VFR since by default the rnav waypoints associated with that airport and the related approaches are also unavailable. Only twice have I come across this though. One main limitation of the FMS the memory.

Funny that we could plug in a Garmin (540) now a days and have a more capable unit.
 
  • Like
Reactions: JLF
Calvin and Hobbs Meter said:
I heard somewhere that Honeywell wasn't servicing the XLS anymore, and that if our box broke down we would have no choice but to replace it. I've never actually seen that notice myself though. If true, I need to convince a line guy that our lav port is located in the FMS, and that it needs to be topped off with some blue juice.

We have also found that most airports with runway lengths below 5,000 ft are not stored in the box. Meaning, we can only go in VFR since by default the rnav waypoints associated with that airport and the related approaches are also unavailable. Only twice have I come across this though. One main limitation of the FMS the memory.

Funny that we could plug in a Garmin (540) now a days and have a more capable unit.
Click to expand...

Unless you are flying a lot of international you need to change your database subscription you are using. If you go down to just Canada, US, and Latin America you will gain airports down to 2500 feet. Check out http://www.honeywellbusinessaviation.com/resources/dyn/files/767867z731a23c8/_fn/direct-to-fms-newsletter-2012-q1.pdf and look at page 5 and 6 to find the database that suits your needs. Just call Honeywell and they should change your subscription for no charge.
​
I am almost sure that Honeywell is still supporting the XLS but I know what you mean about Garmin. Our Honeywell database for the Citation is over 3K a year and in the Cessna 340 with 2 530WAAS units it is less than $700 a year.
 
You must log in or register to reply here.
Back
Top