DFW TMA: P-RNAV Problems??

[ebenezer]

Can anybody provide details of an alleged problem (adequate track keeping??) with P-RNAV routes in the Dallas/Forth Worth TMA area where it's rumoured that ATC has had to revert to good old-fashioned radar vectoring??

Just interested....

Thanks in advance for your co-op.

:confused: :ok:

[Scott Voigt]

It's no rumor... We are violating MANY pilots for not staying on the RNAV tracks. Right now they are trying to figure out if it is pilot error, equipment or software. There seem to be varying issues for different aircraft and airlines. Since they have turned it on, we have probably had over 120 deviations.

Atlanta is having issues also...

regards

Scott

[West Coast]

"We are violating MANY pilots for not staying on the RNAV tracks. Right now they are trying to figure out if it is pilot error, equipment or software"

Either you worded it poorly or its a piss poor way to operate. Violate (again, an ASAP gets me out of 99% of what controllers try to get pilots on) then investigate is ass backwards.

Investigate, then make the determination.

BTW, ATC does not violate pilots.

[Scott Voigt]

West Coast;

Well talk to our managment about it, we report the deviations and then QA files the deviation report that goes to FSDO. We went about four months before we started filing deviations, we figured that was long enough to learn to fly the Departures... Pilots are still making errors and creating problems, with airspace deviations or getting to close to other aircraft, QA looks at it either as our fault or the pilots...

Oh and ASAP only gets you out of it if all the parties come to agreement <Grin>...

later

Scott

[West Coast]

"Oh and ASAP only gets you out of it if all the parties come to agreement"

Nope, not the way it works.

[Scott Voigt]

Not if you read the MOU between the airlines and the FAA... Every airlines ASAP shows that the airline, the union and the FAA have to come to concensus for the ASAP to fly, or ASAP is dead at that entity...

regards

Scott

[Euroc5175]

Scott,
Can you advise as to the reason for the deviations that are being observed at DFW?
Are there design flaws in the P-RNAV SIDs? Do you know what criteria was used in the design? Are all aircraft flying the P-RNAV SIDs 'approved' against a proven set of criteria, such as those found in the JAA's Temporary Guidance Leaflet (TGL) 10?
A small-scale P-RNAV arrival trial has been conducted at both Gatwick and at Heathrow, and the radar plots provided show that the aircraft are nailing the procedures time and time again. A P-RNAV SID trial is due to start at Gatwick in the not-too-distant future. I'd be interested to learn as to why such deviations are being encountered with the DFW and ATL procedures.
Regards

[Scott Voigt]

It appears that most of the problems are due to pilots not entering the data correctly, but that is only what we have heard in the interim. They are investigating the FMS boxes as well as the software. So I think it is too early to do a final WHY... The sids are fine as they are done up now, when the info is entered correctly and the box is working they nail it.

We have our standards here for RNAV, I would expect that they are compliant with ICAO, but since I am not ICAO conversant in RNAV, I wouldn't bet the farm on it... Got to run...

regards

Scott

[West Coast]

Talked with our ASAP program manager today. ATC doesn't have any input or are they required to agree as you infer.

[Euroc5175]

Scott,

Thanks for the reply.

In Europe, the P-RNAV standard (TGL-10) prohibits crews from actually entering waypoint data or editing the data already contained in the FMS. The crews simply select the cleared procedure, e.g. GWC1N, in the FMS and the series of waypoints and associated constraints are populated from the database as issued by the database supplier. This requirement of TGL-10 is intended to prevent waypoints being manually entered incorrectly and it seems to work. To the best of my knowledge, the P-RNAV procedures in use in Europe are being flown accurately by those aircraft approved to do so.

[CAP493]

...the series of waypoints and associated constraints are populated from the database as issued by the database supplier.
BUT...the major flaw is that in Europe (currently) there's absolutely no safety regulatory oversight of the accuracy of commercially-produced databases (nor indeed, of commercially-produced charts and docs). So there remains the possibility of inadvertent error during data input which most times could go unnoticed until an aircraft flies off track according to ATC but on track according to its FMC and HSI.

And this from an associated thread:

I had not heard of any specific technical problems with the RNAV arrival and departure procedures until reading your post. I did a quick search and found this interesting discussion which I believe may address your point. If so, it appears that the problem may be generic to many more airports than just DFW in particular. I will reserve judgement on the specific cause until I have seen more information.

Apparently, there are over 60 NASA ASRS reports relevant to this problem of straying off the published track while flying assigned DPs. Evidence appears to point to either crew data entry errors or possible database glitches in the few reports I have so far reviewed. It should allready be SOP to check the flight plan page waypoints against the printed procedure plate following loading of the procedure into the active flight plan. From what I have read of this so far, it might not be a bad idea to re-check the flight plan page after making any modification such as a direct to entry. Looks the the best and last chance to catch any error, whatever the cause.

I have used the RNAV procedures extensively at LAS and a few times at ATL and DFW without experiencing any problems related to dropped waypoints in the flight plan or any track keeping errors. My only problem with these procedures have been related the 90 degree turn on the KEPEC arrival into LAS. The turn anticipation and track keeping ability of the flight guidance system in our aircraft does not appear to be up to the task of completing this turn accurately and requires manual correction most of the time. More of an avionics intergration issue it seems. Works well in all other regards.

In any case, I hope you find the link I provided useful. Also check out this page at NBAA.

Westhawk

Interesting....

:hmm:

[Euroc5175]

CAP493,
With regards to your comment about the lack of regulatory oversight for databases, I thought that this issue had now been resolved and that EASA was providing a letter of approval to the European database suppliers that had passed the regulatory audit, and that the FAA were doing a similar thing over in the US.
There had certainly been a long wait whilst the regulatory oversight issue was addressed but I believe that EASA and the FAA have now done so. Now that the database issue appears to have been resolved, the number of airlines applying to the UK's Safety Regulation Group for P-RNAV approval appears to be on the rise.
Regards.

[Scott Voigt]

West Coast;

The "FAA" portion that I refered too wasn't ATC even though we are FAA <G>, it refered to Flight Standards (FSDO) who approves the airlines ASAP program in the first place and who sit on the event review committee...

regards

Scott

[CAP493]

...EASA was providing a letter of approval to the European database suppliers that had passed the regulatory audit
Don't know about the FAA but...whilst EASA may have put such an arrangement in place, it seems that EASA is far from on top of the issue, primarily because of allegedly poor organisation, lack of resources (= adequate staff) and other institutional problems that are still impacting the organisation's ability to discharge its regulatory functions. As far as NSAs are concerned (i.e. State CAAs/DCAs/DGCAs) I'm not sure that there is still any really effective regulatory oversight of this.