Navaid outtage & SID

[ImbracableCrunk]

I was flying out of Zhengzhou, China last month and was told by my company not to accept the usual SID due to the NDB for the SID being out of service.

It seems to me that a 737-800 with a few GPS's and a nice FMC could probably do just fine without an NBD, but I'm uncertain where the info is to prove or disprove this.

Any suggestions?

[Pugilistic Animus]

If it says ADF required..etc....you are definitely not authorized...also perhaps GPS/RNAV is not approved for navigation i.e the SID is not authorized...or quite simply your company forbids it in their OpsSpecs...All the 'Laws' for DPs or SIDS IAPs...are on the chart or in the OPSpecs

[ImbracableCrunk]

Well, I don't see anything on the ZHCC BS-11D SID chart that says NDB req'd.

I think this is the same logic that was cited when I asked if we could do the GPS-overlay approach for a VOR that was out of service and was told, "No. How can you do the approach without a VOR????"

Still looking for some reg. . .

[Pugilistic Animus]

GPS use is not universally approved for all types of Navigation... very similar to the fact that you can't use GPS in order to calibrate your VOR receiver even though it definitely would work...
you must either do a VOT test or cross check between dual receivers...if you did; this will be the applicable reg*. ---assuming you work for a US carrier---and even if it is approved on the chart .... your OpSpecs are regulatory--and are the company's medium for part 121 compliance!
I'm not being a wise *ss :)

*91.13 Careless or reckless operation

(a) Aircraft operations for the purpose of air navigation. No person may operate an aircraft in a careless or reckless manner so as to endanger the life or property of another.
(b) Aircraft operations other than for the purpose of air navigation. No person may operate an aircraft, other than for the purpose of air navigation, on any part of the surface of an airport used by aircraft for air commerce (including areas used by those aircraft for receiving or discharging persons or cargo), in a careless or reckless manner so as to endanger the life or property of another.

[ImbracableCrunk]

Yes, yes, yes. POM/FOM is a reg. However, a Chief Pilot saying something over the phone or on a note on his desk is decidedly not.

Pan-Ops, FARS, whatever. I'm looking for something black and white and reg-based.

[BizJetJock]

You're looking at it back to front.
The point is that if it is not an RNAV SID then you need to have all the beacons on the route serviceable, since they are your navigation reference. The same with the VOR approach example.
The fact that you are using your nice FMS to get the a/c along the track is irrelevant, you are supposed to have the raw data displayed to ensure that you actually are following the correct track.
The problem that still exists in large chunks of the world is that modern GPS/FMS systems are too accurate! They take you to where the beacon is supposed to be rather than where it actually is, and all the flight testing for obstacle clearance was done by someone tracking the real beacon.
So if you are not cross checking the raw data you may be in for a shock one day!:ouch:

[Pugilistic Animus]

From the FAA instrument Procedures Handbook although the criteria for you may be PAN-OPS and not TERPS not familiar at all with JAR-OPS--so I cant comment:

PROCEDURAL NOTES
Another important consideration to make during your
flight planning is whether or not you are able to fly
your chosen departure procedure as charted. Notes giving
procedural requirements are listed on the graph
portion of a departure procedure, and they are mandatory
in nature. [Figure 2-25 on page 2-25] Mandatory
procedural notes may include:
• Aircraft equipment requirements (DME, ADF,
etc.).
• ATC equipment in operation (RADAR).
• Minimum climb requirements.
• Restrictions for specific types of aircraft (TURBOJET
ONLY).
• Limited use to certain destinations.
There are numerous procedural notes requiring specific
compliance on your part. Carefully review the
charts for the SID you have selected to ensure you can
use the procedures. If you are unable to comply with a
specific requirement, you must not file the procedure
as part of your flight plan, and furthermore, you must
not accept the procedure if ATC assigns it. Cautionary
statements may also be included on the procedure to
notify you of specific activity, but these are strictly advisory


and
§ 119.49 Contents of operations specifications.

(a) Each certificate holder conducting domestic, flag, or commuter operations must obtain operations specifications containing all of the following:
(1) The specific location of the certificate holder's principal base of operations and, if different, the address that shall serve as the primary point of contact for correspondence between the FAA and the certificate holder and the name and mailing address of the certificate holder's agent for service.
(2) Other business names under which the certificate holder may operate.
(3) Reference to the economic authority issued by the Department of Transportation, if required.
(4) Type of aircraft, registration markings, and serial numbers of each aircraft authorized for use, each regular and alternate airport to be used in scheduled operations, and, except for commuter operations, each provisional and refueling airport.
(i) Subject to the approval of the Administrator with regard to form and content, the certificate holder may incorporate by reference the items listed in paragraph (a)(4) of this section into the certificate holder's operations specifications by maintaining a current listing of those items and by referring to the specific list in the applicable paragraph of the operations specifications.
(ii) The certificate holder may not conduct any operation using any aircraft or airport not listed.
(5) Kinds of operations authorized.
(6) Authorization and limitations for routes and areas of operations.
(7) Airport limitations.
(8) Time limitations, or standards for determining time limitations, for overhauling, inspecting, and checking airframes, engines, propellers, rotors, appliances, and emergency equipment.
(9) Authorization for the method of controlling weight and balance of aircraft.
(10) Interline equipment interchange requirements, if relevant.
(11) Aircraft wet lease information required by §119.53(c).
(12) Any authorized deviation and exemption granted from any requirement of this chapter.
(13) An authorization permitting, or a prohibition against, accepting, handling, and transporting materials regulated as hazardous materials in transport under 49 CFR parts 171 through 180.
(14) Any other item the Administrator determines is necessary.
(b) Each certificate holder conducting supplemental operations must obtain operations specifications containing all of the following:
(1) The specific location of the certificate holder's principal base of operations, and, if different, the address that shall serve as the primary point of contact for correspondence between the FAA and the certificate holder and the name and mailing address of the certificate holder's agent for service.
(2) Other business names under which the certificate holder may operate.
(3) Reference to the economic authority issued by the Department of Transportation, if required.
(4) Type of aircraft, registration markings, and serial number of each aircraft authorized for use.
(i) Subject to the approval of the Administrator with regard to form and content, the certificate holder may incorporate by reference the items listed in paragraph (b)(4) of this section into the certificate holder's operations specifications by maintaining a current listing of those items and by referring to the specific list in the applicable paragraph of the operations specifications.
(ii) The certificate holder may not conduct any operation using any aircraft not listed.
(5) Kinds of operations authorized.
(6) Authorization and limitations for routes and areas of operations.
(7) Special airport authorizations and limitations.
(8) Time limitations, or standards for determining time limitations, for overhauling, inspecting, and checking airframes, engines, propellers, appliances, and emergency equipment.
(9) Authorization for the method of controlling weight and balance of aircraft.
(10) Aircraft wet lease information required by §119.53(c).
(11) Any authorization or requirement to conduct supplemental operations as provided by §119.21(a)(3).
(12) Any authorized deviation or exemption from any requirement of this chapter.
(13) An authorization permitting, or a prohibition against, accepting, handling, and transporting materials regulated as hazardous materials in transport under 49 CFR parts 171 through 180.
(14) Any other item the Administrator determines is necessary.
(c) Each certificate holder conducting on-demand operations must obtain operations specifications containing all of the following:
(1) The specific location of the certificate holder's principal base of operations, and if different, the address that shall serve as the primary point of contact for correspondence between the FAA and the name and mailing address of the certificate holder's agent for service.
(2) Other business names under which the certificate holder may operate.
(3) Reference to the economic authority issued by the Department of Transportation, if required.
(4) Kind and area of operations authorized.
(5) Category and class of aircraft that may be used in those operations.
(6) Type of aircraft, registration markings, and serial number of each aircraft that is subject to an airworthiness maintenance program required by §135.411(a)(2) of this chapter.
(i) Subject to the approval of the Administrator with regard to form and content, the certificate holder may incorporate by reference the items listed in paragraph (c)(6) of this section into the certificate holder's operations specifications by maintaining a current listing of those items and by referring to the specific list in the applicable paragraph of the operations specifications.
(ii) The certificate holder may not conduct any operation using any aircraft not listed.
(7) Registration markings of each aircraft that is to be inspected under an approved aircraft inspection program under §135.419 of this chapter.
(8) Time limitations or standards for determining time limitations, for overhauls, inspections, and checks for airframes, engines, propellers, rotors, appliances, and emergency equipment of aircraft that are subject to an airworthiness maintenance program required by §135.411(a)(2) of this chapter.
(9) Additional maintenance items required by the Administrator under §135.421 of this chapter.
(10) Aircraft wet lease information required by §119.53(c).
(11) Any authorized deviation or exemption from any requirement of this chapter.
(12) An authorization permitting, or a prohibition against, accepting, handling, and transporting materials regulated as hazardous materials in transport under 49 CFR parts 171 through 180.
(13) Any other item the Administrator determines is necessary.
[Docket No. 28154, 60 FR 65913, Dec. 20, 1995, as amended by Amdt. 119–10, 70 FR 58823, Oct. 7, 2005; Amdt. 119–13, 75 FR 26645, May 12, 2010]

[ImbracableCrunk]

AOPA Online: Air Traffic Services Brief -- Use of GPS in lieu of DME/ADF (http://www.aopa.org/whatsnew/air_traffic/gps_in_lieu.html)



Effective July 16, 1998, pilots may substitute IFR-certified GPS receivers for DME and ADF avionics for all operations except NDB approaches without a GPS overlay. GPS can be used in lieu of DME and ADF on all localizer-type approaches as well as VOR/DME approaches, including when charted NDB or DME transmitters are temporarily out of service. It also clarifies that IFR GPS satisfies the requirement for DME at and above Flight Level 240 specified in FAR 91.205(e). This approval represents a major step toward removing the need to retain DME or ADF in our cockpits for any reason.
Note: Air carrier operators should consult their operations specifications and their principal operations inspector for approval.
Limitations

There are still three instances in which DME or ADF are still required.

NDB approaches that do not have an associated GPS overlay approach must still be flown using an ADF.
A non-GPS approach procedure must exist at the alternate airport when one is required to be filed by regulation. If the non-GPS approaches on which the pilot must rely require DME or ADF, the aircraft must be equipped with DME or ADF avionics as appropriate. GPS substitution for DME/ADF is not permitted in this case.
DME transmitters associated with a localizer may not be retrievable from your GPS until the manufacturer incorporates them in the database. Pilots are not authorized to manually enter coordinates.
Yes, I've underlined a note about the op-specs. This is the FAA's take, but I'm in Korea for the time being.

[Pugilistic Animus]

The problem that still exists in large chunks of the world is that modern GPS/FMS systems are too accurate! They take you to where the beacon is supposed to be rather than where it actually is, and all the flight testing for obstacle clearance was done by someone tracking the real beacon.
So if you are not cross checking the raw data you may be in for a shock one day!http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/shiner.gif

Excellent point :ok:

[Pugilistic Animus]

Then what BizJetJock Said it the most conservative answer so probably the best---until you get clarification...sorry I definitely can't say anything about Korean Law:)

[Denti]

It really depends on your OPS Manual. For example we do not need any raw data coverage at all as long as we do have 2 FMC, 2 IRS and 2 GPS operating and ANP is below required RNP (0.15 for approaches, 0.30 for departures). Even if raw data is available it does not need to be cross checked if the above conditions exist. Granted, that is under EU-OPS instead of US or korean regulations.

[ImbracableCrunk]

I'm digging through the company website trying to dig up an English version of the ops specs.

I've seen airports that weren't where airports were supposed to be in China databases, so I know what a couple of the remarks are about. I've also flown RNP approaches in some scary valleys, so I understand the breadth and limitations of the dangers.

I've already been given a conservative answer by the CP. I needs me some facts.

[CL300]

China WGS84 compliant ????

[ImbracableCrunk]

From ICAO:

China advised APANPIRG/19 that
WGS 84 implementation is in
progress and planned to be
completed in 2010 for all existing
airports. All new airports will use
WGS84 immediately.


So that's a maybe. . .

[Pugilistic Animus]

Always follow what the CP says:\

if he or the DFO are friendly types then..you could ask for clarification or an explanation, or a referenc in the procedures...but if the 'OspSpecs' are not in English :\

[reynoldsno1]

Bear in mind that the default coding for a waypoint is fly-BY - conventional procedure fixes are, by definition, fly-OVER. The fifference could be critical under some circumstances.

[ImbracableCrunk]

Bear in mind that the default coding for a waypoint is fly-BY - conventional procedure fixes are, by definition, fly-OVER. The fifference could be critical under some circumstances.

Which circumstances did you have in mind?

That aside, my original question wasn't so much on construction of SIDs and TERPS. It's a question of where does it say what my CP says it says - that you can't do a pilot-nav SID with two FMCs, two IRSs, two GPSs, two autopilots, two pilots and a partridge and a pear tree?

We fly enroute with navaids out all the time. VOR U/S? No prob. Where does it say that that is acceptable?

[Pugilistic Animus]

I would think that if their WGS84 compliance is questionable...it could be dangerous the reason I think it's allowed in the US is because the data is internally consistent and predicated on a single reference datum.

[LOAL]

Jepp ATC - Flight Procedures - General Principles (Extracted from ICAO Doc 8168)

Section 1.4 - Use of Flight Management System (FMS) / Area Navigation (RNAV) Equipment
1.4.1 Where FMS/RNAV equipment is available, it may be used to fly conventional procedures provided:

the procedure is monitored using the basic display normally assosiated with that procedure; and...
the tolerances for flight using raw data (dispayed) on the basic display are complied with.

The italicized text is my interpretation of this line.

So as stated above, even thou the aircraft is perfectly capable of operating independently of the ground based aids, you are still required to tune, identify and display the "raw data" for SID's and overlay approach's VOR's etc.

Hope this helps in some way? :ok:

[ImbracableCrunk]

LOAL,

That's the type of info I'm looking for. Thanks.

[GlueBall]

was told by my company not to accept the usual SID due to the NDB for the SID being out of service.

But would ATC actually assign you this particular SID knowing that the NDB is out...? That's the real question.

[ImbracableCrunk]

But would ATC actually assign you this particular SID knowing that the NDB is out...? That's the real question.

They did and it being China, they weren't to impressed with our request for a vector or something else in lieu of the procedure.

[BOAC]

But would ATC actually assign you this particular SID knowing that the NDB is out...? That's the real question. - quite common in Europe (and UK) in my experience. You point out their error, there is fluster, and then "expect radar vectors":)

[Denti]

Probably because many european airlines have the approval by now to fly departures or arrivals even if the navaid for that departure or arrival is u/s.

[BOAC]

Some have, some have not - it cannot be assumed!

[Denti]

Yup, but how are they to know? So they just try the usual way (SID) first and then offer something else if you can't do that.

[BOAC]

Yup, but how are they to know?- How about - Nav aid = u/s -"Are you able RNAV SID 06C" - OR "If able, RNAV 06C or radar vectors available" - seems simple to me.

This actually dates back to well before RNAV capability and was then just down to 'not thinking'.

[A321COBI]

A later model of a 737 should be fine
http://www.boeing.com/news/releases/2007/photorelease/q4/K64229_lg.jpg

[reynoldsno1]

Which circumstances did you have in mind?

Obstacle abeam, say right of track - fix established to ensure aircraft passes safely over before turning right.
Using fly-by waypoint would have aircraft use turn anticipation and turn inside fix, compromising procedure as designed....

[ImbracableCrunk]

Obstacle abeam, say right of track - fix established to ensure aircraft passes safely over before turning right.
Using fly-by waypoint would have aircraft use turn anticipation and turn inside fix, compromising procedure as designed....

You're talking about a conditional waypoint, right? eg. reach 2500' or fix YADDA then proceed direct BLAHH. I don't think that has any relation to LNAV and navaid outtages, does it?

The FMC really doesn't care that the NDB isn't there. It knows how the waypoints are coded and where it should go next - navaid or no.

It seems that there's no logic to this, just how conservative your controlling agency, POI, etc is.

[rudderrudderrat]

It seems that there's no logic to this, just how conservative your controlling agency, POI, etc is.

Your FMS data base probably gets updated once a month and I bet there is some data that gets corrupted every time.

We departed Hong Kong about 10 years ago with an FMS data way point error. It was coded fly by rather than fly over. The aircraft started the SID turn early, so we selected heading and delayed the turn until the correct DME distance out. A following company aircraft on the same departure received a Terrain GPWS warning.

Unless the chart says approved for GPS NAV - then you are obliged to cross check your position using the published ground based aids. Anybody trusting someone else's NAV coded data accuracy implicitly is an accident waiting to happen.

[Denti]

The database should be updated at least once every 28 days for each AIRAC cycle.

I do share concerns about database "bugs" or corruption, having seen the results first hand departing FRA where wrongly coded departures lead us outside the noise monitored sector and resulted in the LBA pressing charges up to 10.000€ against the captain on that flight.

However the database providers now promise that their quality management system assures a correctly coded database every cycle, and apparently the authority follows that reasoning and allows us to fly without displaying and checking raw data for departures.

[idg]

Sorry but classic PRC!! Been there before.

PRC is not yet WGS-84, therefore the BS NDB is required (as previously stated) and if it is u/s then you were correct to ask for a different solution.

Practically however the FMS will fly the plane more than adequately and if you want to depart then this is what you will have to do.....as will the 'local' operators!

Some Jepp charts have MSAs based on NDBs so the only way to get the 25DME is to use the FMS progress page (or similar). Khaosiung in Taiwan is an example of this. If your ops manual does not specify that substitution is acceptable with Navaid outages or for MSA calculations, then you must ask for radar guidance. Would also actually need to confirm with PRC AIP that ZHCC is approved for radar vectors before accepting. Not all PRC airports are so approved...radar monitoring but not vectoring...beware! Possibly why they were reluctant.

Furthermore since you would be above the MSA by DUMAG terrain clearance would not be an issue and direct WXI would also be a practical solution.

[Checkboard]

It really depends on your OPS Manual. :rolleyes:

Actually it depends upon your regulating authority. :hmm:

IFR nav - approved navaids.
RNAV - approved enroute (above the MSA) navigation.
B-RNAV (RNP 5)- approved navigation below the MSA, when approved navaids are also available and monitored.
P-RNAV (RNP 1)- stand alone navigation below the MSA (terminal navigation, SIDs & STARS)
P-RNAV (RNP 0.5) - stand alone instrument approaches.

[reynoldsno1]

You're talking about a conditional waypoint, right? eg. reach 2500' or fix YADDA then proceed direct BLAHH. I don't think that has any relation to LNAV and navaid outtages, does it?


No, I'm not - I'm talking about the difference between a fly-OVER waypoint & a fly-BY waypoint, both very much related to LNAV.

A conventional procedure flown using RNAV must treat each fix/waypoint as fly-OVER i.e as it would be using conventional navigation aids.

[dispatchshmoe]

We fly enroute with navaids out all the time. VOR U/S? No prob. Where does it say that that is acceptable?

Under 121 Flag OpSpecs, B034(e)(7), which states

An approved area navigation system fix may be substituted for a required en route ground facility when that facility is temporarily out of service, provided the approved navigation system has sufficient accuracy to navigate the aircraft to the degree of accuracy or navigation performance required for air traffic control over that portion of the flight.

[ImbracableCrunk]

Actually it depends upon your regulating authority. http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/yeees.gif

IFR nav - approved navaids.
RNAV - approved enroute (above the MSA) navigation.
B-RNAV (RNP 5)- approved navigation below the MSA, when approved navaids are also available and monitored.
P-RNAV (RNP 1)- stand alone navigation below the MSA (terminal navigation, SIDs & STARS)
P-RNAV (RNP 0.5) - stand alone instrument approaches.

So the B738 I was in was flight planned with "NAV/RNAV1 RNAV5 RNVD1E2A1." It sounds like we were filed with the EQ to do the SID, at least.

Checkboard, can you point me to a source for that list. I've seen it before, somewhere. . .

[BOAC]

This (http://www.pprune.org/tech-log/394971-prnav-rnp-1-equipment-requirements.html) may help. What does your Ops Manual say?

[ImbracableCrunk]

Well, I gave up looking for the Op Specs. I went back the to the FOM and found the appropriate section.

Here's something that I think backs up what most of the posts have been saying:


• P-RNAV procedures apply to operations including departures, arrivals, and
approach phases (From Initial Approach Fix (IAF)/Initial Approach Way
Point (IAWP) to Final Approach Fix (FAF)/Final Approach Way Point
(FAWP)). Final Approach Segment and Holding patterns shall be flown
with conventional procedures.
• Type A, B procedure apply to departure and arrival procedures
• Pilot operating in a designated airspace as RNAV 1 or RNAV 2 shall
confirm the RNP value in the FMS matches with required RNP Value 1 or 2.and this section:

■ Equipment required for operation in RNAV 1 area and
RNAV 2 area
• Effective Navigation Database
• One FD in NAV Mode
• Single FMC, Single (M)CDU, Dual IRU, Single ND
• Required Equipment should be accorded between RNAV 1 area operation
and RNAV 2 area
― Single GPS Receiver(inculding RAIM funtion) or,
― DME/DME Receiver or,
― VOR/DME Receiver *(1) or,
― DME/DME/IRU Receiver *(2)To me it sounds like we were equipped and approved to do what I thought we were.

Maybe the company just decided (like many have noted) "It's the PRC. Don't do it without raw data."

[LLLK]

It is worrying when even the FOM's have it wrong. RNAV 1 may not be flown using VOR/DME as a position sensor. It was allowed with P-RNAV but never with RNAV 1.

Second point - the datahouses code the conventional procedures taking account of fly-by and fly-over as appropriate - provided they have not made any mistakes, and there are QA systems in place to guard against that, then it is usually OK to fly the departure using GPS as the sensor. It is NOT OK to manually enter fixes in the FMS and then fly the manually created procedure.

Third point - Some regulators have approved operators to fly conventional procedures using GPS, some of those require the conventional aids to be monitored, some don't care if the aids are monitored or not, some don't care if the aids are there or not. Some regulators don't allow the ANSP to publish procedures based upon GNSS so I would expect that they don't allow their operators to use it either!

Fourth point - B-RNAV is definitely NOT to be used below MSA.

I thought that performance based navigation was supposed to make things simpler.:ugh:

[LLLK]

Oh yes, and P-RNAV = RNAV 1 (except for the bit about VOR/DME) not RNP 1 or RNP 0.5

[Permafrost_ATPL]

A lot of answers that are not appropriate to the question :-)

Checkboard has given the answer in official wording. Here is a simple version:

- once you are navigating towards the failed SID Navaid (remember, the original question is about SID, not approach), you must be above MSA UNLESS IT'S A P-RNAV SID (I am assuming here we are talking about minimum B-RNAV equipped aircraft).

Simples.

So it all depends where that failed NAVAID is in the SID. On a side note, you are allowed to START a turn towards the failed Navaid below MSA (e.g. when passing 2000', turn towards ABC). You just need to be above it once your FMGS starts tracking towards it (using GPS/IRS). Again, all of this does not apply in the case of P-RNAV.

P

[RMC]

Our ops manual that we can fly an RNAV STAR below MSA up to the Final Approach Waypoint (FAWP).

My understanding of this is that an FAWP should appear on RNAV STAR plates...but the handful of places we fly into with RNAV STARs don't depict a FAWP only an IAF?

Can anyone direct me to a chart with a FAWP and verify if this restriction is similar for other airlines with both BRNAV and PRNAV approval?

[Speedwinner]

If I have a SID which is RNAV/GPS. Can i fly it without GPS wenn there are waypoints like NEGRA which are undefined. So i mean with raw data nav not pointable?

Or do I just have to check wether my RNP and actual RNP are good?

Thanks

[reynoldsno1]

My understanding of this is that an FAWP should appear on RNAV STAR plates

The FAWP is part of the instrument approach, not the STAR - the STAR ends at the IAF. There is no ICAO charting requirment to have the FAWP on the STAR chart, and I have never ever heard of thus before - I assume it is a company 'thing'?

If it is an Ops Manual requirement, then it sounds as though you need company customised charts.

[LLLK]

The term FAWP was used to define the extent of the P-RNAV approval. You have approval to fly RNAV 1 (P-RNAV) up to but not past the FAWP. (These days the term FAWP has been replaced by the term FAF.)

There is no requirement for the STAR to end anywhere near the FAF. However, there are some States that publish STARs or Approach Transitions which end at the IF or FAF.

See EDDF Transition to Final Approach

As for RNAV/GPS SIDs - you can only fly them if you have GPS as a navigation sensor and are approved for Basic RNP 1 or RNAV 1 (P-RNAV)

[Denti]

As for pure GPS SIDs i would agree, however for P-RNAV SIDs or RNAV/GPS SIDs only the applicable RNAV ANP is required, not a GPS if you can achieve the ANP without it. We had all our 737 classics without GPS certified to P-RNAV and could fly everything down to RNP 0,5 legally with them, except for pure GPS-Procedures.

[LLLK]

We had all our 737 classics without GPS certified to P-RNAV and could fly everything down to RNP 0,5 legally with them, except for pure GPS-Procedures.

If the SID is charted as RNAV(GNSS) then the ANSP has not assessed the DME/DME coverage and has only protected the procedure for GNSS (GPS). I would call that a pure GPS procedure. If the ANSP has done a DME/DME assessment then the chart title should just be RNAV - no '/GPS' - and then the RNP<0.5 would apply.

[FE Hoppy]

I would recommend that almost everyone on this thread needs to do a Performance Based Nav course and read the ICAO PBN doc. The terms P-RNAV and B-RNAV and many others used in this thread have no relevance in China where they have adopted and are implementing PBN precisely as prescribed by ICAO.

If you want to fly RNAV1 or RNAV2 procedures you need to ask for them. If you ask for a radio nav based procedure in China that's exactly what you are expected to fly and if the navaid is out then you can't.

Not everywhere is surveyed to WGS84 yet which is why you cannot use an RNAV system to fly non RNAV procedures and when flying RNAV1 then you must only use GPS, DME/DME or DME/DME/IRS position solutions. VOR/DME updating is not allowed.

[alosaurus]

FE Hoppy... I also need to do a performance based nav course. Please can you advise how the WGS84 survey (which I have seen mentioned but don't really know what it is) will protect you (once fully completed) when flying an RNAV system with non RNAV procedures.

In the meantime will work on the management to get me on a course!

Thanks in advance

[FE Hoppy]

alosaurus,

In the simplest terms WGS84 is a grid system used by GPS based on the position of true north in 1984. Your GPS position is with reference to this grid.
Now imagine taking your chart and drawing the lat and long lines a little offset to the north and west. Your gps tells you you are N10W10. on your chart using the original grid there is a navaid at this position but because the GPS grid and the charts grid are not the same when you tune the navaid you find it is displace from your position by the difference between the two grids.
Any navaid based procedure will have you at the appropriate position because it's based on the grid used to define the navaids position and your position is referenced to the navaid.
If you try and use an RNAV system that is using GPS as it's position solution on a procedure based on a different grid and ground based navaids, you may well find yourself offset from where you should be. And this may put you somewhere unsafe.
Some aircrafts AFMs specify that GPS position updating is prohibited in areas which are not WGS84.
So you shouldn't fly a radio based procedure using only GPS based RNAV without using the navaid raw data to confirm your position unless (as is the case in many places) the local regulations allow.