Navaid outtage & SID
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was told by my company not to accept the usual SID due to the NDB for the SID being out of service.
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But would ATC actually assign you this particular SID knowing that the NDB is out...? That's the real question.
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Originally Posted by Glueball
But would ATC actually assign you this particular SID knowing that the NDB is out...? That's the real question.
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Yup, but how are they to know?
This actually dates back to well before RNAV capability and was then just down to 'not thinking'.
Which circumstances did you have in mind?
Using fly-by waypoint would have aircraft use turn anticipation and turn inside fix, compromising procedure as designed....
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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....
Using fly-by waypoint would have aircraft use turn anticipation and turn inside fix, compromising procedure as designed....
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.
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It seems that there's no logic to this, just how conservative your controlling agency, POI, etc is.
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.
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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.
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.
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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.
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.
It really depends on your OPS Manual.
Actually it depends upon your regulating authority.
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.
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?
A conventional procedure flown using RNAV must treat each fix/waypoint as fly-OVER i.e as it would be using conventional navigation aids.
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We fly enroute with navaids out all the time. VOR U/S? No prob. Where does it say that that is acceptable?
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.
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Actually it depends upon your regulating authority. 
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.
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.
Checkboard, can you point me to a source for that list. I've seen it before, somewhere. . .
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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:
and this section:
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."
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.
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.
■ 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)
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)
Maybe the company just decided (like many have noted) "It's the PRC. Don't do it without raw data."
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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.
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.