GPS approach

[michelda]

Hi guys,

I'm new on these type of approaches!!
Somebody can explain me differences between:
Gps approach
Gnss approach
Rnp approach
Rnav approach
Rnp ar approach

Thanks very much for your help
Michelda

[FE Hoppy]

Wow, that's a half day course right there my friend.

[rudderrudderrat]

Hi michelda,

Gps approach = Approach using GPS satellites position updating (uses the USA System of Global Positioning Satellites)
Gnss approach = Approach using Global Navigation Satellite System (can use present GPS and the new European Galileo Sat Nav System of the future) (eg GNSS APP LGW 26L required accuracy = 0.3nm)
Rnp approach = Area Nav Approach using DME/DME, VOR/DME, or Satellite system for position updating with a position accuracy of "X". (X is usually 1 nm)
Rnav approach = Area Nav Approach as above - but not necessarily to the same required accuracy
Rnp ar approach = Not certain - think it might be the Arrival Procedure leading to the RNAV Approach.

[FE Hoppy]

Oh go on then.
Gps approach = Approach using GPS satellites position updating (uses the USA System of Global Positioning Satellites) Now being phased out and replaced by RNP APRCH
Gnss approach = Approach using Global Navigation Satellite System (can use present GPS and the new European Galileo Sat Nav System of the future) (eg GNSS APP LGW 26L required accuracy = 0.3nm)don't forget the Russian, Chinese and indian systems and see note above
Rnp approach = Area Nav Approach using DME/DME, VOR/DME, or Satellite system for position updating with a position accuracy of "X". (X is usually 1 nm)Includes RNP approach procedures and RNAV (GNSS-based) approach procedures designed with a straight segment, the accuracy normally being 0.3.

GNSS is the primary navigation service that supports RNP APCH procedures. The acceptability of the risk of loss of RNP APCH capability due to satellite failure or loss of onboard monitoring and alerting function must be considered during procedure design.

The missed-approach segment may be based on RNAV or conventional navigation procedure.

RNP APCH navigation specification does not include specific requirements for communication or surveillance.

Rnav approach = Area Nav Approach as above - but not necessarily to the same required accuracyObsolete term now being replaced by RNP
Rnp ar approach = Not certain - think it might be the Arrival Procedure leading to the RNAV Approach.An RNP approach procedure featuring special aircraft aircrew and approach procedure authorization by the regulatory authorities.

It normally applies to airports where there is complex terrain and limited airspace and requires accuracy normally between 0.3 and 0.1.

Only GNSS is the allowed to be the navigation source and achievable actual RNP precision shall be predicted.

The specification excludes specific communication and surveillance requirements.

[aterpster]

RNP AR is advanced RNP with Authorization Required. Minimums can be predicated on containment areas as small as 2 X RNP 0.10. VNAV of a high degree of accuracy is also a required element.

[FlightPathOBN]

Quick rule of thumb..

RNP APCH: TF to TF legs only
RNP AR: TF-RF-TF legs

GPS and GNSS are synonymous... GPS is the name of the US based sat system...globally, it is called GNSS. Currently only GPS (US), GLONASS (Russia) are operational...Beidou (China), Galileo (EU), and IRNSS (India) are a long way off, perhaps by 2020.

Interestingly, in the GPS accuracy diagrams, I never paid attention to the outer band at 2200m accuracy, Omega. It wasnt until I visited the Omega Tower, at about 1400feet,the tallest structure in the Southern Hemisphere, in AUS, did that click....

[michelda]

Thanks very much for your replies.

Another question......
FSIA (seychelles) Rnav(gnss) rwy 13
Rnav (rnp) rwy 13
EDDM (frankfurt) Rnav (gps) rwy 07C

An airline must be authorized for flying these procedure? (entry in AOC certificate)

Do you use same procedures when you fly these approaches?

Michelda

[FlightPathOBN]

Not sure what to make of the RNAV (GNSS) RW13 approach to FSIA....didnt find one called "RNP" to compare. (was looking for RNP AR...)

For all intensive purposes, this would be RNP APCH, but an offset approach. with a min of 1870', I would not use this as an example of what to do....

RW31 has a straight in ILS approach, yet the RNAV GNSS is offset as well..

Is this a Jepp design?

[Denti]

Hmm, weird one. The RNAV (GNSS) Y 13 has on the LIDO map a note that says Straight-In Not Authorized. 1870 is of course only the minimum for a very low GA gradient, shown as circling minimum on the LIDO chart. Since there is a RNAV (RNP) Z 13 approach available which has a 410' minimum that would be my first choice. It requires an RNP of 0.15 and is only available between 5° and 46° C.

[FlightPathOBN]

Concur,

not sure why the offset...I didnt find the RNP track with Jepp, so not sure why it is so different from the GPS track, if it is...so not knowing that I just looked at the 2.5 missed number.

Same with 31, straight in ILS, but offset GPS.....what does LIDO show on this?

[Sir George Cayley]

RNP = Required Navigation Performance - just though I'd mention that.

Now for 10 points - PBN?

SGC

[alphacentauri]

C'mon, thought you had a hard one for us

PBN = Performance Based Navigation

:)

[FlightPathOBN]

PBN: what happens when the French get involved with RNP....

now one just has to find AC in Seychelles that have a GPS.....

[alphacentauri]

PBN: what happens when the French get involved with RNP....


HAHA GOLD :D

A relevant comment considering what they are currently trying to do to the BARO-VNAV criteria......seems a "change it because you don't understand it" mentality applies

[FlightPathOBN]

exactly why we have RNP procedures in OZ...

and the frogs are in study mode.

[Oktas8]

As an aside....

The description above does not apply to all countries. In some, the RNP specification excludes satellite-only based position fixes. Satellite fixing as part of a full FMS installation is fine, of course.

[aterpster]

Oktas8:

As an aside....
The description above does not apply to all countries. In some, the RNP specification excludes satellite-only based position fixes. Satellite fixing as part of a full FMS installation is fine, of course

ICAO has, thus far, adopted the U.S. criteria (FAA Order 8260.52) for RNP AR IAPs. The qualification process is quite rigorous and contained in a separate advisory circular (AC 90-101A). (Both the criteria Order 8260.52 and AC 90-101A are posted on the FAA's website.)

In addition to GPS position a minimum of one IRU is required for extraction in the event of a failure of GPS. This is not required to operate to RNP 0.30 minimums so long as the missed approach does not require RNP of less than 1.0 (telescoping missed approach).

As a practical matter thus far all aircraft approved for minimums of less than RNP 0.30 (to as low as RNP 0.10) and/or missed approaches of RNP less than 1.0 all have triple IRUs because the airplanes were designed for oceanic.

Also, RNP AR requires a lot more than GPS and IRUs. The FMS and flight computer redundancy is far greater than with "ordinary" RNAV. TAWS is mandatory as well. Thus, the integrity, alerting, and monitoring is quite rigorous and necessary to achieve a target safety factor of E10-7 that 2XRNP will not be breached.

[Potsie Weber]

As a practical matter thus far all aircraft approved for minimums of less than RNP 0.30 (to as low as RNP 0.10) and/or missed approaches of RNP less than 1.0 all have triple IRUs because the airplanes were designed for oceanic.

We fly to 0.15 RNP AR. 737-800. 2 x IRU

[Denti]

Yup, the NG is certified for RNP 0.10 as standard level with only two IRS. And for GNSS based CAT I approaches, CAT IIIb is currently in the testing phase.

[aterpster]

Denti:

Yup, the NG is certified for RNP 0.10 as standard level with only two IRS. And for GNSS based CAT I approaches, CAT IIIb is currently in the testing phase.

As I said only one IRU is required. And, as a practical matter most presently authorized RNP AR airplanes have 3 IRUs.

[FlightPathOBN]

2 working systems, hence 3...if you go below 2 you cant use the RNP level..


did you mean GBAS CATI, with CAT III in cert?