Date: 201510
Local time of day: 1801-2400
Location: DCA.Tower, DC
Flight conditions: VMC
Light: Night
Aircraft: B737-800
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Landing
Airspace: Class B DCA
ATC / advisory: Tower DCA
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness
Second reporter function: First Officer; Pilot Not Flying
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Fuel Issue
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew Landed As Precaution
Contributing factors: Aircraft; Human Factors; Procedure
Primary problem: Human Factors

Narrative: While enroute to DCA; we noted that we were running behind on fuel; 1;100 lbs at ILM. Some of this we attributed to leveling at FL370 instead of FL390 and a slightly higher than planned takeoff weight. It was apparent that fuel would be tighter than expected on landing; but not critical given it was a clear night. Later; we were given delaying vectors and an early descent; well before what was required to meet the CAPSS arrival. Just outside of Potomac Approach's airspace; we were assigned a 110 degree turn to the left and slowed to 250 kts. Throughout we were keenly aware of our fuel situation as we were turned back onto the arrival and crossed the WAVES Intersection with 5;000 lbs; about 2;300 lbs less than planned. FO (First Officer) suggested that we declare minimum fuel but I felt that we were going to land well above reserve fuel (3;700 lbs) and did not think it necessary. As we entered the downwind segment of the arrival; we asked the controller how long our final would be. He stated that we should expect a base turn in about 15 miles; which I felt was within our minimums. We were turned in and cleared for the River Visual to 19 which I backed up with the RNAV (RNP). Approach was normal as we switched to tower and heard the tower controller clear one aircraft for takeoff and another into position. As we continued the approach; the tower controller cleared us to land and asked us to 'square the turn to final' as he cleared the next aircraft for takeoff. At this point; with fuel at about 4;200 lbs; the aircraft on the runway apparently did not initiate his takeoff roll quickly enough and Tower instructed us to go around. I believed that; while we could go around and get back to DCA with expedited handling; that it was safer for us to land provided that the aircraft ahead had cleared the runway. We had the departing aircraft in sight throughout and noted he was well into his takeoff roll. I instructed FO to tell the tower that we were 'Unable' and declare minimum fuel-which he did. The controller cleared us to land once again. We watched the departing aircraft lift off and climb and we touched down normally several seconds later. At no time were we in a position where we could not have gone around if the aircraft had not cleared the runway. Fuel on landing was 4;000 lbs.My most significant error in this event was not declaring minimum fuel with the approach controller. At the very least; we would have received expedited handling and; with the tower in the loop; the departure of the next aircraft might have been delayed to prevent any conflict. My judgment regarding the fuel level appropriate to make that declaration did not include any contingencies for unexpected events. Either with or without the minimum fuel call; I should have declared an emergency to the tower controller. This would have been entirely appropriate since I was exercising my PIC (Pilot in Command) authority to deviate from a clearance to insure a safe outcome.


Second narrative: During the flight to DCA; the Captain and I noticed the fuel burn was above flight plan estimates. This was not a cause for concern since the flight plan included DISP ADD fuel in excess of the extra burn we were experiencing; and the weather at destination was above what would be expected to cause delays. Before joining the CAPSS ONE Arrival at WAVES we received an early descent and two separate vectors for spacing with accompanying speed reductions; which consumed additional fuel. After rejoining the arrival the Captain and I discussed fuel requirements and agreed we would land with a full complement of reserve fuel (3800 lbs) plus an additional 800 lbs (4600 lbs total); if we did not receive any additional vectors for spacing. Over the Washington DC area the Captain asked me to query the controller how far we would fly northwest before being turned back in for the River Visual 19 approach. The controller advised we were number 5 and it would be approximately 15 miles before we turned in. The Captain and I discussed declaring a Minimum Fuel Advisory. We decided it was not necessary as we were shortly thereafter vectored northeast and then cleared for the River Visual 19 approach. An additional factor in our decision making was the fact the controllers and pilots of other aircraft were doing a great job of maintaining proper separation on the approach. The approach was normal; we maintained visual contact with the required visual cues and the preceding aircraft throughout. After the preceding aircraft touched down; we heard the tower controller clear an aircraft onto the runway and 'keep it rolling for immediate takeoff; traffic on a 2 'mile final.' The tower controller then instructed us to 'square your turn to final'. Despite the non-standard phraseology and limited airspace; the Captain did what he could to provide more separation with the runway and departing traffic. The tower controller cleared the aircraft for takeoff; but the aircraft seemed to delay for a few moments. As we rolled out on final I observed the departing traffic accelerating down the runway. At about 200 feet AGL the tower controller instructed us to go-around. The Captain announced we were unable to go around due to minimum fuel and needed to continue the approach. I relayed the information to the tower controller; and after a brief pause he re-cleared us to land. I observed the departing traffic lift off the runway about the same time the aircraft automated voice announced '100'; and advised the Captain the traffic was airborne before the automated voice announced '50'. We landed without incident.The biggest thing I could have done to prevent this incident would have been to more strongly advise the Captain of the need to declare a Minimum Fuel Advisory. The Captain and I were fixated on landing traffic in deciding not to do so; and never envisioned the possibility of the tower controller trying to fit a departure between aircraft conducting a demanding visual approach at night. Declaring a Minimum Fuel Advisory would have helped both us and the tower controller by removing any doubt as to whether a departure could be accommodated before our arrival. The departing aircraft would have simply waited on the ground until after we landed before getting clearance onto the runway.


Synopsis: B737 flight crew arriving DCA noted excess fuel consumption enroute but still expected to land with 4;600 pounds on a clear night and TRACON is not advised. The Tower cleared another aircraft to takeoff with the B737 crew inside three miles; then issues a go around when the spacing appeared too tight. The B737 Captain declined; stating minimum fuel and the Tower reissued a landing clearance.