bookworm wrote:
NCY, are you aware of the criteria and level of scrutiny that was applied before adding “or GPS” to existing conventional IAPs? And what proportion of approaches turned out to be unsuitable for GPS overlay?
I don’t know a percentage, but most VOR and NDB approaches were included in the initial overlay program. They had to be in the GPS database, and not all were included because of coding issues with leg types. In the database, they had a small GPS suffix that would be displayed, even though it was not part of the title of the procedure. These were phase 2 procedures which required that the equipment and facility had to be in working order. In phase 3, all of the approaches that an overlay was permitted had the procedure name changed to include ’or GPS". Approaches that were phase 3, did not require the equipment to be installed or the facility to be operating. By early 2001, all of the phase 2 procedures had been converted, although by then many never became phase 3. As time has gone on, it is the policy of the FAA to eliminate the phase 3 procedure “or GPS” portion when the airport has RNAV (GPS) approaches to serve the runways. Most phase 3 approaches are now gone. So now there is no point to flying an overlay in the US, with very few exceptions.
I must shamefully admit I regularly do the ILS at L2K using GPS instead of ADF.
The other day, during my annual IR revalidation I did a conventional departure from LFPN. After departure from 07L you intercept TSU R077° until 4,1 DME TNO and the turn left to intercept bearing 301° from POY NDB. I diligently set up the instruments for departure, and identified the NDB. When turning to intercept the bearing from the NDB the ADF needle did not turn. POY is apparently too far away.
So much for using NDB. The problem with that departure is that there is no GPS overlay unless you enter one of the POGO departures.
Aviathor wrote:
I diligently set up the instruments for departure, and identified the NDB. When turning to intercept the bearing from the NDB the ADF needle did not turn. POY is apparently too far away.
Interesting. Did you also check that the NDB actually “pulled” the ADF needle after tuning it?
Is any lobby or hope glimpsed that this regulatory approach by EASA might change at some point? Put another way what safety case is there for not allowing GPS overlays where an NDB is part of an approach? other than the databases will have to be updated to load the new approach.
RobertL18C wrote:
Put another way what safety case is there for not allowing GPS overlays where an NDB is part of an approach? other than the databases will have to be updated to load the new approach.
There is no safety case, but there is no such thing as an overlay in Europe. The database ones are purely done by Jepp. US overlays were official.
Jason agree, but why hasn’t EASA followed the USA and allowed overlays to be added to the databases – officially. For reasons of a personal propensity towards finger malfunction am not a believer in DIY overlays or DIY approaches.
Hopefully this would be a red tape reduction for all – just getting rid of the old drag producing LF antenna wire (old kit) must be justified on energy saving grounds.
No idea Robert. It seems a little too pragmatic to happen in Europe. The risk assessment would prob kill it.
I can’t understand why the UK/EASA haven’t allowed them to be flown in overlay like they did in the USA.
Its it a revenue/job creating scheme making everyone apply for approaches from scratch.
As someone who only useful navigation aid in his aircraft is an ADF I find all the NDB approaches to be quite useful and I don’t have the GPS database costs either.
