Date: 201405
Local time of day: 0601-1200
Location: ZZZ.TRACON, US
Flight conditions: VMC
Light: Daylight
Aircraft: B737 Next Generation Undifferentiated
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
Airspace: Class B ZZZ
ATC / advisory: TRACON ZZZ
Aircraft component: FMS/FMC
Component problem: Design
Reporter organization: Air Carrier
Reporter function: Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Distraction; Workload; Confusion
Second reporter function: First Officer
Anomaly: ATC Issue All Types; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented; Flight Crew Requested ATC Assistance / Clarification
Contributing factors: Aircraft; Chart Or Publication; Procedure
Primary problem: Ambiguous

Narrative: ATIS said to expect RNAV RNP (Y) XXL and this was loaded.  There is a RNAV (Y) XXL that begins at ZZZZZ IF on the arrival.  Approach Control verified to expect the RNP (Y) XXL approach into ZZZ; but said it would be radar vectors to ZZZZZ1 for the RNP (Y) to XXL.  This is not a charted route/procedure on the approach from ZZZZZ.  Since this is not charted from ZZZZZ to ZZZZZ1; we questioned ATC and verified that there would be a radar vector to ZZZZZ1.  At this point; we deleted the RNP Y XXL that started at ZZZZZ. The confusion and programming errors resulted from this deletion and not reloading the entire [arrival] to regain the points [subsequent] after ZZZZZ.  As the pilot flying; I expected to be vectored from ZZZZZ to ZZZZZ1.  That was not what ATC intended.  After crossing ZZZZZ; we continued briefly on the heading that was the inbound course to ZZZZZ on the arrival.    About the time we were going to ask ATC about a heading; they asked if we had made the turn depicted on the [arrival to ZZZZZ2].  We stated no and was a given a heading with further vectors to ZZZZZ1.  On the ground; given a number to call.  The first thing stated from ATC in that conversation was that this happens a lot and they are trying to figure out why.   I further spoke with Company ATC representative; X; and he stated that this is a known issue that Company and the ATC people are working on to find a solution.  He said they are aware of the route discontinuity issue with being on vectors to ZZZZZ1 instead of a continuous approach from ZZZZZ. The flight crew must be made abundantly aware what is wanted from ATC.  If the IF of ZZZZZ1 is to be used instead of ZZZZZ; then the remainder of the arrival must be reloaded to include the arrival fixes after ZZZZZ. The note on the arrival should include the possibility of either a GPS or RNP approach from that point; but better would be to (see next).  Have two separate RNP approaches and plates that begin at ZZZZZ to avoid the confusion of beginning the approach at ZZZZZ or ZZZZZ1.  It is a bastardization of the RNAV process to fly over an IF and not use that already charted RNP approach.  This particular charting situation may be unique in the respect of flying to a charted IF on the arrival and approach plate but not fly that approach to that runway. I thought that was the point of RNAV. And of course; crews should be more diligent about the routing and programming to ensure the correct route is loaded.


Second narrative: [Report narrative contained no additional information.]


Synopsis: A B737-NG was removed from the ZZZ RNAV for vectors to the RNAV (RNP) Y XXL ZZZZZ1 waypoint but when the RNAV was deleted the ZZZZZ and ZZZZZ2 waypoints on the RNAV (RNP) Y XXL were also erroneously deleted which caused a track deviation prior to radar vectors to ZZZZZ1.