My plane is not certified for RNP—yet. But when it is, I’ll be ready to go.
RNP (Required Navigation Performance) utilizes GPS (Global Positioning System), the aircraft FMS (Flight management system), and procedures that enable pilots to fly to lower minimums in areas of critical terrain or obstacles.
How can RNP do this? RNP, unlike RNAV (Area Navigation/Radar Navigation) takes into consideration “containment” where the airplane proves it can fly tighter tolerances utilizing GPS, FMS and trained pilots, enabling us to use lower landing minimums.
RNP in a quantitative value is .3 NM or less, and defines the accuracy limit of the approach. Containment is the protection limit, and is two times the RNP value. For example, with a .3 RNP value there can be no obstacles within .6NM of the course. Observing Actual Navigation Performance, ANP, is accomplished on the MCDU PROG page where we will monitor the aircraft's accuracy.
A key term in the RNP world is the RF (Radius to Fix) leg. The significance of the RF leg mandates a prescribed ground track to be flown, where wind, true airspeed…etc., have no impact.
- "Special Aircraft and Aircrew Authorization Required."
- The aircraft must be certified.
- Pilots must be trained.
- High/low temperature restrictions are to be adhered to and found on the Jeppesen briefing strip.
- See the above information: NA below 6 degrees C and above 59 degrees C.
- Autopilot use is mandatory from the initial approach fix (RF leg) until visual reference with the landing runway. In the example above the RF leg begins at GLRIA.
- A maximum of 165 knots is required on the RF leg.
- Remember the A330 has groundspeed mini and could increase speeds above 165 knots, vigilance is necessary.
- Do not proceed direct to a fix that begins the RF leg. Excessive approach angles may take the aircraft beyond the containment airspace.
If you're certified for an RNP or have been trained to fly this type of approach, I would love to know the tricks. Or my friends in the tower--- do you have anything you could add to increase our knowledge of this type of approach? Thank you all.
Enjoy the Journey!