Date: 201705
Local time of day: 1801-2400
Location: BUR.Airport, CA
Flight conditions: Mixed
Weather elements / visibility: 10
Light: Night
Aircraft: B737 Next Generation Undifferentiated
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class C BUR
ATC / advisory: Tower BUR
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness
Second reporter function: First Officer; Pilot Flying
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: General None Reported / Taken
Contributing factors: Weather; Human Factors; Company Policy
Primary problem: Human Factors

Narrative: Prior to departure BUR was using Runway 8; but there was a NOTAM that I missed that showed [Runway] 8 would be closed later. Enroute to BUR I was completing the prior to descent duties and noticed that Runway 8 was no longer available and closed. They were using ILS 8 circle to 15. There was a ceiling at 3300 ft with ten mile visibility and the winds were out of the south at 9 knots. I sent a message to Dispatch asking them to call the Tower and see if we could get Runway 8 because it was late and that was a less risk oriented approach. Our review of the airport pages showed that for arrivals to 15 at night the use of the RNAV visual Runway 15 is required after official sunset. The FO and I discussed the approach and determined that the RNAV visual needed 5000-5 nm as a minimum. The ceiling was at 3300 with ten miles visibility. The RNAV visual is an approach for arrivals from the north; and since we were coming from the west rather than the north; we determined that we could still use the RNAV 15 GP guidance while circling after using the LOC to 8 to get below the high clouds and execute the circle; thus complying with the requirement to use RNAV vis guidance. Neither the approach plate to Runway 8 nor the procedure guidance prohibited a circle at night to Runway 15. We discussed the circle that the FO would fly and that we would put the RNAV visual 15 into the FMC after we started to circle and put the final in from GOBLT to give us VNAV glidepath guidance to the runway with its 3.25 degree glidepath. Prior to arrival we received an ACARS message from Dispatch saying that 8 was unavailable and that with that 3300 ceiling that we might need to divert. We did not receive a diversion plan. I replied that we had an instrument approach to 8 and that we could circle to 15. We received no other response from Dispatch for the remainder of the flight. We were also busy setting up for the approach. The FO flew a flawless Localizer to 8; broke out at 4000; and leveled off at 2500 in excellent visibility. He completed the circle; intercepting final approximately two miles inside of GOBLT while using VNAV and VASI guidance to runway. The landing was uneventful. Upon clearing the runway the ACARS received a number of messages telling us that we needed to divert. The flight behind us diverted to ONT. At the gate I contacted the Dispatch and told them that I did not think we needed to divert flights for a 3300 ceiling. The [company policy manual] does not stipulate that circling to 15 is prohibited at night. What it says is that the use of the RNAV visual is required after official sunset. Circling to 15 is also not prohibited on the approach plates. The issue is that we need to use RNAV guidance to Runway 15 after official sunset; which we did. Circling is not an abnormal procedure; although rare; we used to do it all the time at [another airport]. The difference in BUR is the terrain issue from the north. My understanding of the RNAV visual to 15 is that it was designed to prevent EGPWS warnings from the terrain on the way into BUR on arrivals from the north and east. Flying the LOC to 8 to get below the high clouds and then circling while using the VNAV guidance to 15 seemed like a logical; safe; and prudent course of action that complied with the requirement to use the RNAV 15 at night; while at the same time completing the visual segment of a circling the approach. Anywhere in California to Burbank is a quick flight and does not lend itself to ambiguity concerning Runway 15. The [company policy manual] discusses the use of RNAV at night to 15 but it does not specifically prohibit the circle from 8. If that is the intention then it just needs to say that. We are all problem solvers; if the ILS is out; the RNAV Z will do; if that doesn't work; how about the VOR; etc. We were trying to complete the flight safely and comply with the intent of the [company policy manual]. I thought the intent of that RNAV approach was to prevent EGPWS events from the north. I probably should have queried Dispatch more; but there was some ambiguity there as well.


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


Synopsis: B737 flight crew reported executing a circle to land maneuver at BUR that may have violated company policy.