Workload; Distraction; Situational Awareness
Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural FAR
General None Reported / Taken
Airspace Structure; Procedure; Human Factors
The GIBBZ arrival is a very busy arrival and it was even busier than usual that day. I got distracted both by the approach and the added distractions of two close encounters with VFR traffic and many turns and descents from ATC at a busy time of the arrival. We landed with the seat belt sign off. Passing through FL180 we were distracted by the busy GIBBZ arrival. Just as we were passing through 10;000; where I would usually check the seatbelt sign; we were given our runway assignment and it was not what we had expected (we were given [Runway] 19R) and we were given what sounded like an urgent traffic alert with a turn off the arrival to avoid VFR traffic. We also had to call the Flight Attendant; because we didn't have a sterile light. Then; as we were trying to prepare for the approach to Runway 19R we were given another turn back towards the airport; then a frequency change. On checking in we were given another traffic alert of a VFR target less than 2 miles and 500 FT above our assigned altitude. We picked up this traffic visually just as the resolution advisory was being enunciated. We called and kept the traffic in sight visually until we were clear of conflict; then finished the prep for the approach; transferred controls; did a quick brief; and switched controls back. I think I called for the in-range; but we were now less than 5 miles from the final approach fix and were given more vectors and a frequency change to Tower. Now I began configuring for the approach as Tower asked us to keep our speed up to the marker. Unfamiliar with [Runway] 19R; I spent a little time reviewing the distance to the runway and altitude of the FAF to figure out what a safe speed to the marker would be since I know that we have a lot of configuration issues with IAD approaches. Once we were completely configured; I called for the 'Before Landing' Checklist and we must have skipped the In-Range Checklist; because the Flight Attendant called us once we were stopped on the taxiway and informed us that the seatbelt sign was still off. I've been told that we are trying to stop doing the GIBBZ; I think that's a great way to reduce distractions during the arrival phase into a busy airport.
Air Carrier Captain reports forgetting to turn on the seatbelt sign prior to landing at IAD due to the extremely busy arrival and approach phase. Vectors to avoid VFR traffic and the GIBBZ arrival were cited as the major distractors.