Regional Jet 900 (CRJ900)
Flight Crew Air Transport Pilot (ATP)
Situational Awareness; Distraction
Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Unstabilized Approach
Flight Crew Executed Go Around / Missed Approach; Flight Crew Became Reoriented
Human Factors
During ILS approach (PF); approaching the final approach fix; directed 'check spoilers; gear down; before landing checks.' Tower had initially cleared us to land outside the FAF. During the landing checklist; ATC canceled landing clearance due to departing traffic. This caused an interrupt; after the ATC read back; completed the checklist. At approximately 1000 AGL; the radar altimeter warning horn sounded. I verified the gear indications; which indicated not down and locked. Commenced missed approach; vectored back around and landed normally.Lack of proper checklist procedure after interruption. The PNF had not extended the landing gear when directed and improper crosscheck by PF had missed this during checklist. Contributing factors; ATC was a distraction with a landing clearance; then cancellation; then clearance to land again on the final segment; after approach control had issued a maintain 170 knots to the FAF; with subsequent configuration change (flaps and airspeed); to fly the ILS and landing.Proper adherence of the SOP on interrupted checklist and cross checking. Diligence to avoid complacency interpreting aircraft state versus expected aircraft state. It would be a good feature if the aircraft would give an alert if the flaps are extended beyond 20 degrees with the gear still up.
There were distractions from ATC. The landing clearance was cancelled and the controller was difficult to understand at times. We were also complacent when verifying the green gear down indications during the before landing checklist. [Suggest] strict adherence to the checklists and actually checking what the list is calling for. We were complacent.
CRJ-900 flight crew reported going-around after receiving an alert that the landing gear was not extended on short final.