Am I lucky with R9 that my kit is allowed to use RF legs?
I would be surprised if you are. What does it say in your flight manual supplement? Mine for example says:
The Garmin GNSS navigation system complies with the equipment requirements of AC 90-105 and meets the equipment performance and functional requirements to conduct RNP terminal departure and arrival procedures and RNP approach procedures without RF (radius to fix) legs.
The only Garmin system that supports RF legs is the G1000 STC upgrade system for the King Air. The capability is available in all the Garmin WAAS systems, but is currently disabled. Garmin was hired by the FAA to conduct a study to see what was required for all levels of pilots to fly the RF leg. They used several minimum configurations with a simple CDI, both with and without a moving map, roll steering autopilot, or flight director. Several complex back to back to back RF legs were flown and pilots of all experience levels easily adapted to them with minimal training and maintained the 95% RNP standards. Garmin recommended that the FAA reconsider their stance, but so far the FAA has not done so, although it is said to be coming. It will take a simple software change to enable the leg type in the Garmin GPS units.
I would be surprised if you are. What does it say in your flight manual supplement?
As at the moment I only have the general manual for R9 and not the one with the aircraft I have sent an email to Avidyne to find out. I will report once I get news.
Avidyne just responded:
RNAV GPSS and RNAV RNP are supported and legal to fly with R9 and IFD540. However if the RNP approach contains an RF leg or has the extra AR (authorization required) tag associated with it then no, R9 and 540 are not legal to use. Those are a small percentage of RNP and GPSS approaches.
Note: on second reading I have emailed Avidyne again to ask for clarification. The above sound like the existence of RF legs or AR makes it a no while he was talking that RNAV RNP were no problem. I’ll post what I receive back.
The terminology is confusing. See 1-2-2 in this part of the AIM
Chart label RNAV (GNSS) = RNP APCH operation
Chart label RNAV (RNP) = RNP AR APCH operation
Bookworm, you are spot on the terminology issue so much so that the airline I fly for has produced a cheatsheet to make sure we get the approach flown to legal minimums.
I can quite see how when under pressure of an unplanned diversion confusion could creep in and apparently following the publication of the document my employers training department agree with you !
In the US, we had names for all this stuff before ICAO renamed them, primarily to cause confusion and NIH factor. ICAO now wants the RNAV (GPS) name to go away and be replaced with RNP. Our FAA finally grew a pair and refused to change the names for a third time. Ya’ll in Europe won’t be so lucky.
After a bit more conversation with Avidyne – over this weekend :-) – I eventually got this:
Yes, R9 will fly the RF legs, but it is not “approved.”
I’m still trying to figure out what the quotation marks around the word approved mean.
What do RF legs mean in practice?
In “classical” GPS behaviour, autopilot coupled, you have a route made up of a number of waypoints, the AP is in NAV mode, and it, ahem, flies the route, more or less through the waypoints.
Even if it does it really stupidly, like a human pilot might do if having to manually turn the course pointer on a KI525 HSI to the new track value when it pops up on the GPS, it will still be laterally within some fraction of a mile of some “perfect track”.
I can’t help thinking there is a lot of job creation in all this, since GPS did to the navigation business what the CD did to the vinyl record business (i.e. trash it, except for a small band of enthusiasts who believe in gold plated power plugs etc) and they sit in their committees inventing all kinds of stupid procedures and standards.
A few years ago, one prominent UK pilot had an “audience” with an official with the UK CAA over PRNAV which at the time threatened to kill 99% of IFR GA by requiring a stupid level of compliance with some gold plated interpretation of the masterpiece of ambiguity called TGL10. With the CAA man in the RHS they hand-flew some procedures, showing that PRNAV can be met in a hand flown spamcan. The CAA then accepted this, although a year later, at a Eurocontrol “navigation workshop” I went to, the (now ex) CAA man backtracked on it. The whole business is full of politics…
Even a KLN94 flies within a fraction of a mile of any series of waypoints, no matter what track changes there are.
Now everything is being renamed with “RNP” in the name… why?
