Date: 201401
Local time of day: 1201-1800
Location: MSP.Airport, MN
Flight conditions: IMC
Weather elements / visibility: Icing; 6
Light: Dusk
Aircraft: Citation X (C750)
Operator: Corporate
Operating under: Part 91
Flight plan: IFR
Mission: Passenger
Flight phase: Final Approach; Initial Approach
Airspace: Class B MSP
ATC / advisory: TRACON M98
Reporter organization: Corporate
Reporter function: Pilot Not Flying; Captain
Reporter qualification: Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Human factors: Confusion; Situational Awareness
Anomaly: ATC Issue All Types; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
Detector: Person Flight Crew; Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Air Traffic Control Issued Advisory / Alert; Flight Crew Executed Go Around / Missed Approach
Contributing factors: Human Factors; Procedure
Primary problem: Ambiguous

Narrative: We were continuously slowed during our initial descent and while being vectored for our ILS approach. We were slowed from 170; 160; 150 and finally our slowest approach speed from about 10 miles to 6 miles out. Passing through 3;500 FT; Approach told us 'approach clearance canceled. Level off at 3;000 FT.' We leveled off at 3;000 FT and began cleaning up the airplane; expecting to be vectored for another approach. Instead; just inside the outer marker; Approach re-cleared us for the approach and told us to contact Tower. We both quickly looked at our position and decided we were within approach tolerances and started to rejoin the approach. While quickly making this decision; we failed to think about the fact that the aircraft was no longer in the approach configuration. Tower called us and stated we were low on the approach and wanted to verify we were on the ILS; as we were off the localizer by one dot and were drifting toward the parallel runway. We elected to go-around to be vectored for the same ILS approach. We landed uneventfully out of the approach. Factors that affected this approach: 1) ATC continuously slowing us down and vectoring us from the initial descent through the approach. This was a clue that we were being vectored in tight on the approach. 2) ATC 'cancel approach clearance; level off at 3;000 FT;' this caused confusion as the crew was expecting to be re-vectored for the approach and ATC was planning to re-clear us into the approach; even though this was never stated. ATC canceled the clearance until they had spacing required behind a heavy airplane. When the spacing was met; ATC re-cleared us on the approach. We looked at where we were on the approach and tried to salvage the approach. We failed to recognize the time needed to get the airplane back into approach configuration. In hindsight; the best decision would've been to decline the second approach clearance and ask for vectors for another approach. During the transition back onto the approach; the autopilot was disengaged and the airplane was allowed to drift off the localizer and glideslope. 3) Desire to keep traffic flow efficient. There is a desire by the crew to help ATC fit everyone into the airspace efficiently. This thinking can sometimes be an obstacle in the decision to go-around.




Synopsis: CE750 Captain reports getting low and off course after misunderstanding ATC's intentions during an ILS approach. A go-around is initiated and the second approach is uneventful.