Date: 201902
Local time of day: 0601-1200
Location: DCA.Airport, DC
Aircraft: B737-800
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Takeoff / Launch
Airspace: Class B DCA
ATC / advisory: Tower DCA
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; First Officer
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Human factors: Situational Awareness
Anomaly: ATC Issue All Types; Conflict Ground Conflict; Less Severe
Detector: Person Flight Crew
When detected: Taxi
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: Aircraft X was cleared to lineup and wait on Runway 1 at DCA. Due to closely approaching landing traffic on Runway 1; ATC instructed us to have engines spooled up and ready for immediate takeoff to which we complied. Upon setting our brakes on the runway; ATC cleared a Regional Jet (RJ) for takeoff from Runway 33. As the RJ started their takeoff roll; ATC cleared us for takeoff on Runway 1. Because the RJ had just started to move and was nowhere near crossing the intersection of Runway 1/33; I did not immediately respond to ATC. Approximately 2 seconds later; ATC again cleared Aircraft X for takeoff. Because the RJ still had not crossed Runway 1; I told ATC that we were waiting for the RJ to cross our runway; and I confirmed the takeoff clearance. The RJ safely passed the RWY 1/33 intersection and we then safely executed our takeoff.Immediately after takeoff; ATC (still with DCA tower) instructed us to stop our climb at 2;000 feet and to maintain minimum forward speed. We entered IMC at approximately 1;700 feet and complied by maintaining approximately 180 knots with our flaps extended. ATC subsequently cleared us to 3;000 feet; then approximately 30 seconds later to 4;000 feet. Upon reaching 4;000 feet; we were directed to switch to Potomac Departure and were subsequently told to resume the SID and climb to 17;000 feet.No further significant events occurred.I understand and support DCA controller's efforts to maximize traffic flow into/out of DCA. However; I believe ATC unnecessarily put two; potentially three (landing aircraft); at risk during IMC conditions. I do not believe that we should have been cleared for takeoff until the crossing RJ traffic was clear of the Runway 1/33 intersection. In addition; I do not believe that a (faster) 737 should have been directed to takeoff so closely behind a (slower) RJ on the same departure. Given the proximity of landing traffic on Runway 1 and the departing traffic on Runway 33; I believe it would have been much safer to have kept any aircraft from positioning on Runway 1 until those two stated aircraft were safely clear. Furthermore; had we complied with immediately beginning our takeoff roll when first instructed; would have made the lack of appropriate separation even direr.As stated; due to the proximity of landing traffic on Runway 1 and the departing traffic on Runway 33; I believe it would have been much safer to have kept any aircraft from positioning on Runway 1 until those two aircraft were safely clear. To prevent this from occurring in the future I recommend the following:1. Do not clear an aircraft for takeoff until crossing traffic is safely clear of the intersection.2. Ensure appropriate separation before clearing a (faster) aircraft to follow a (slower) aircraft on the same departure; especially in IMC conditions.3. Minimize the use of 'immediate takeoff' for departing aircraft. This has become increasingly common at DCA and unnecessarily puts at risk both landing and departing aircraft.




Synopsis: Pilot reported ATC issues relating to separation of traffic on the ground and in the air during departure from DCA.