Story ID: 
FMS Constraints Preempt Citation's TEB Approach
By: Matt Thurber
Caption: A pilot flying a Cessna Citation 560 to Teterboro Airport had to divert to Westchester County Airport due to flight management system limitations.
Word Count: 552
A pilot flying a Cessna Citation 560 on January 20 to New Jersey's Teterboro Airport had to divert to Westchester County Airport in White Plains, New York, because the jet’s flight management system (FMS) did not store the instrument approach procedure in use for the arrival. At the time, weather was clear with more than 10 miles of visibility, with north winds at 12 knots. The assigned approach was the RNAV (GPS) X Rwy 6 at Teterboro.

According to a note sent to members of the Teterboro Users Group (TUG) on January 24, while en route over Virginia, a Washington Center controller told the Citation pilots that if they were unable to fly the RNAV (GPS X) approach, they would have to fly to another airport. The pilots asked if they could fly the (GPS) Y Rwy 6 approach but they were told this wasn’t possible and that they would have to fly to a different airport, so they diverted to Westchester County.

The FMS’s software limitations mean that it couldn’t “process multiple approach indicators for the same type of approach, e.g. RNAV (GPS) X Rwy 6 and the RNAV (GPS) Y Rwy 6,” according to TUG. “Jeppesen will typically code the approach with the lowest landing minimums. Since the RNAV (GPS) Y Rwy 6 has the lowest landing minimums, that’s the one that was coded in the nav-database for the RNAV (GPS) approach to Runway 6 at KTEB.” TUG pointed out that this isn’t a Teterboro problem and affects other airports with multiple approach indicators and that a software or hardware upgrade might be necessary to avoid this problem.

However, at Teterboro this issue is compounded by the unique nature of the New York metropolitan airspace and traffic at nearby Newark International Airport. The north winds and heavy holiday traffic “led NY TRACON and KEWR to simultaneously utilize the ILS Rwy 4R and RNAV (GPS) X Rwy 29 [at Newark] in an effort to mitigate upstream ground and airborne delays,” TUG explained. Controllers were unable to give the Citation pilots the (GPS) Y Rwy 6 approach into Teterboro because its missed approach procedure conflicts with the final approach courses for the two approaches in use at Newark. The RNAV (GPS) X Rwy 6 approach into Teterboro “was designed to decouple the two airports when operating in this configuration,” TUG noted. 

Controllers also could not simply give the pilots a visual approach to Runway 6 at Teterboro, explained Heidi Williams, NBAA director of air traffic services and Infrastructure, because the airspace is usually too busy for controllers to allow that. 

TUG said it “has engaged in comprehensive discussions with FAA ATC, [Port Authority of New York and New Jersey, the airports’ operator], an FMS OEM, and NBAA in an effort to identify solutions that will eliminate or mitigate future such occurrences. While a crew may request vectors or a course to a waypoint/fix located on the RNAV (GPS) X for a subsequent visual approach in VMC, the airspace may be too congested for ATC to accommodate. Similarly, requests for airborne holding or delaying vectors may not be granted, as they significantly increase the workload for the MUGZY controller (the busiest and most complex of [New York] Tracon’s positions) and require additional coordination with upstream/adjacent facilities.”