Date: 202012
Local time of day: 1201-1800
Location: ONT.Airport, CA
Flight conditions: IMC
Weather elements / visibility: 10
Light: Daylight
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Cargo / Freight / Delivery
Flight phase: Initial Approach
Airspace: Class E SCT
ATC / advisory: TRACON SCT
Reporter organization: Air Carrier
Reporter function: Pilot Flying
Human factors: Confusion; Workload
Anomaly: ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Unstabilized Approach
Detector: Person Flight Crew
When detected: In-flight
Contributing factors: Airspace Structure; Company Policy; Human Factors; Procedure
Primary problem: Procedure

Narrative: ATIS was advising ILS approaches in use. We requested the RNAV Y for pilot proficiency reasons. The request was approved by the final approach controller. At the end of the RNAV arrival; we were put on the published heading and told to expect vectors onto final for the RNAV Y approach by the final approach controller. We requested but were denied direct both initial approach fixes to start the approach. We were given 2 vectors; the last being [Heading] 290 and the clearance to fly heading 290 maintain 4;300 ft. until established on the final approach course cleared for the RNAV Y approach as we were vectored toward the course between the initial approach fixes. The approach became challenging at that point because the final approach course and glidepath anticipation cues were not visible and therefore we were unable to arm the approach. Additionally; the 4;300 ft. restriction left us high rather than leave us in a position to descend to 2;900 ft. in the space between the initial approach fixes because the width of the lateral course at that point is much narrower than a localizer signal. The IMC and terrain rich environment added to the concerns at this point. I feel that part of this challenge was created by the technique US air traffic controllers are using to get aircraft onto RNAV approaches. Rather that clear an aircraft to a fix on the approach; they are trying to vector them onto final as they would for an aircraft flying an ILS approach. My first safety concern is that there is not final approach course to intercept when flying an RNAV approach such as the localizer transmitting out bound from the runway for many miles. Rather there seems to be courses from one fix to the next all the way down the published approach. When ATC says 'fly heading xxx until established on the final approach' there isn't a final approach to intercept. I question whether a clearance of that wording is procedurally correct on RNAV approach. There are no examples I can find in company manuals or the Airman Information Manual the depicts starting an RNAV approach at anywhere other than a fix on the approach. I have had this type of vector onto final clearance for an RNAV approach for RNAV approaches in other U.S. destinations also so I feel the safety threat posed by this type of RNAV clearance is widespread in the USA. I have never received a clearance like that outside of the USA. Outside the USA; I have always been cleared to fix to start the RNAV approach. My second safety concern is that if that type of RNAV approach clearance is correct; we do not train that at any point during initial or recurrent training. All of our simulator training clears the aircraft to a fix on the approach when cleared for an RNAV approach. If the type of ATC clearance we got is procedurally correct we never see it in training.




Synopsis: Air Carrier pilot reported ATC issued a vector to intercept the final approach course for an RNAV approach which does not have a final approach course. The reporter stated this type of clearance is issued routinely by U.S. ATC but overseas they are always issued direct to a fix to begin the approach.