Go Direct helps users achieve RNP approval

 - January 5, 2009, 5:04 AM

For most flight department managers, the thought of navigating the maze of FAA rules to fly required navigation performance (RNP) approach procedures is enough to stop them dead in their tracks. That’s the reason Honeywell has launched Go Direct Services, a turnkey consulting offering designed to help business jet operators take advantage of new RNP SAAAR (special aircraft and aircrew authorization required) procedures the FAA is adding at scores of airports around the U.S.

The benefit of an RNP SAAAR approach is that it can carve out a highly precise, curved path through the sky that usually results in lower landing minimums–sometimes much lower. But getting approval is a costly and complex endeavor requiring submittal of monthly operational reports to the FAA, pilot simulator training and operations manual revisions. Considering that fewer than 100 RNP SAAAR approaches have been published so far, most operators probably won’t go to the trouble of gaining approval until their home airport has an RNP approach. But as more RNP procedures are created, operators who forego such approvals will be at a disadvantage compared with those who are SAAAR compliant.

The FAA plans to publish 60 new RNP SAAAR procedures per year for the next two years. Some airports scheduled to receive an RNP approach in the next 12 months include Teterboro, N.J.; Aspen and Eagle, Colo.; Monterey, Calif.; and Scottsdale, Ariz. If your airport or an airport you use often offers an RNP SAAAR approach, the approval can mean the difference between landing or having to execute the missed approach and consider other options.

Take, for example, the available approaches to Runway 31 at Sun Valley, Idaho. The normal decision altitude for the GPS approach is 1,790 feet versus 974 feet for the RNP SAAAR procedure. Even more dramatic is the case of Bishop, Calif., where a gently snaking RNP SAAAR flight path allows properly trained crews flying properly equipped airplanes to descend to 323 feet versus being saddled with a 2,227-foot minimum descent altitude using the previous approach, an LDA DME procedure that avoids high terrain on both sides at Eastern Sierra Regional Airport.

The major advantage RNP procedures have over other types of approach is their tighter lateral boundaries, which allow the creation of curved pathways through mountain valleys or by using so-called radius-to-fix (RF) turns to avoid terrain or obstacles.

The RNP SAAAR approach to Atlanta DeKalb-Peachtree Airport is a good example of the benefits RNP can provide. The approach to Runway 2R incorporates a continuous descending turn that is designed to avoid the tall towers that block the straight-in approach to the field. Due to the east-west flows at nearby Hartsfield-Jackson International, a straight-in ILS or WAAS LPV approach to this runway would be hard to implement, even if the obstacles southwest of the airport were removed.

While WAAS LPV approaches are excellent alternatives to traditional ILS procedures, they have performance limitations that prevent them from incorporating curved paths. The FAA’s RNP program is aimed more at FMS-equipped operators who can fly curved RF legs. Honeywell’s corporate flight department at Morristown Municipal Airport in New Jersey became one of the first in the country to obtain approval for RNP SAAAR operations, gaining certification for its own Gulfstream G450 and G550. Since then Honeywell has been named an RNP SAAAR designated consultant, giving the company the authority to assist other operators and providing the opportunity to create the Go Direct branded service package.

The service offering is split into three categories, the first dealing with aircraft equipage, the second with the operational approval documentation that must be submitted to the FAA and the third with database validation and ongoing RNP SAAAR recordkeeping. Installing RNP-compliant avionics and uploading the latest FMS software adds to the cost of RNP compliance, as does the database validation and monthly record-keeping program. Additional simulator training is required as well, and all of the large training providers are offering RNP-specific courses. Although the process takes around three months to complete and requires additional pilot training, many operators can upgrade to RNP simply by loading new FMS software, according to Honeywell.

“RNP takes advantage of a lot of technology that has evolved over the last 30 years, such as inertial reference systems, GPS and FMS, but it sets a new performance standard here and now,” said Chad Cundiff, vice president of crew interface products for Honeywell. “We want to help get more operators flying in the RNP environment because the capability is so amazing.”

NBAA has provided the FAA with a list of RNP SAAAR procedures that would benefit business aircraft operators. Several of those approaches are in the process of being created now. Honeywell and Jeppesen worked with the FAA to create an RNP SAAAR approach to Morristown’s Runway 5, primarily as an exercise aimed at showing what is involved in developing such procedures at an airport used predominantly by business aircraft operators. Honeywell never gained final approval for the approach, partly because the three major New York-area airports are undergoing a major traffic-flow redesign that may or may not fit with the RNP procedure as designed. After the New York airspace redesign is implemented, Honeywell likely will amend the Morristown RNP procedure as needed to gain approval for it, Cundiff said.

Most newer business jets equipped with Honeywell flight management systems can be upgraded for RNP through a software upload to version 6.1 (for NZ-series FMS equipment) or 7.1 (for Primus Epic-equipped aircraft), both of which will be available next year. Older airplanes might require a new FMS and perhaps other equipment such as an inertial sensor and upgraded GPS receiver. A WAAS GPS receiver is not specifically required, but having one eliminates the need to do a pre-departure RAIM (receiver autonomous integrity monitoring) check. For an FMS to meet the requirements of RNP, it needs to be able to fly a curved path. Also, when the pilot presses the go-around button, the FMS should be able to remain in the nav mode. This latter capability is being addressed through software updates, Cundiff said.

Five Gulfstream operators so far have involved Honeywell in the RNP SAAAR approval process. An operator who is interested in gaining operational approval for RNP can call Honeywell and set up a meeting to determine all that’s required to meet the FAA’s requirements. Honeywell representatives assist the operator with the RNP application as part of a “turnkey” service package included in a $90,000 upfront cost. For an additional cost Honeywell will also handle the database validation and monthly monitoring tasks that for an airline are normally handled by in-house personnel, as well as needed updates to the flight operations manual.