Date: 201202
Local time of day: 0001-0600
Location: LAS.Airport, NV
Flight conditions: VMC
Light: Night
Aircraft: B737-700
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Final Approach
Airspace: Class B LAS
ATC / advisory: Tower LAS
Reporter organization: Air Carrier
Reporter function: Captain
Human factors: Other / Unknown
Second reporter function: First Officer
Anomaly: ATC Issue All Types; Conflict Airborne Conflict
Detector: Person Flight Crew
Result: Air Traffic Control Issued New Clearance
Contributing factors: Human Factors; Procedure
Primary problem: Procedure

Narrative: On our first RNAV visual approach to Runway 19L in Las Vegas after we were fully configured and cleared to land; we were vectored off the approach and told to climb due to an aircraft with a medical emergency. We were vectored for another Visual Approach to 19L. Configured; stabilized; and cleared to land; at 700 FT AGL; we were told to go around. In the process of cleaning up the aircraft and climbing to the assigned aircraft; we were asked if we had traffic in our ten o'clock position below us. I told my First Officer to relay negative. We were given a heading of 170. My First Officer asked the Tower to repeat the heading; and there was no response. At this time; we saw a low aircraft climbing westbound at our ten o'clock; quite close to us; and immediately turned another ten degrees left (160) to adequately stay clear of the traffic. We received no TCAS TAs or RAs. We were vectored for an uneventful landing to Runway 25R. New procedures for LAS go-arounds need modifying. I called the Las Vegas Tower and spoke to the Supervisor to find out what happened. He stated that recent changes handed down demanded that once an aircraft crossed a certain point on their screen; a go-around was immediately issued for the aircraft landing on Runways 19. My concern is this leads to fast moving; converging aircraft in a high workload phase of flight and; in our case; with a nose high attitude and limited visibility of any aircraft below. Some new procedure needs to be expedited to prevent any big problems this might cause in the future.


Second narrative: On second; ATC directed a go-around for 19L; first was for emergency aircraft; a potential loss of aircraft separation occurred. At about 700 to 800 FT AGL on final for 19L; LAS Tower directed a go-around. They then asked if we had the aircraft departing 25R in sight. The Captain did not see them and we replied negative. While performing the required call-outs on the go-around to clean up the aircraft; I heard 'heading 175'. I asked LAS Tower if the heading was for Company flight number. Silence on the radio for three to four seconds. I asked again if the heading was for Company flight number and to please confirm. No answer from Tower. At this point; we could just see the departing aircraft pop up in front of us at our nose for 3;000 FT to 4;000 FT. May have been farther due to the bright lights against the night sky. After the appropriate expletive; the Captain maneuvered the plane to the left to create separation. I then called the aircraft in sight. The rest of the flight was uneventful. The Tower Supervisor told the Captain in a phone call that new FAA rules; enacted one to two weeks prior; mandated the go-around for the intersecting runways and added to the conflict. The nose up position of our aircraft in the go-around did not allow us to see the departing aircraft until it passed at or near our altitude. LAS Tower needs to ensure adequate separation for the intersecting runways. If we continued to land; there would have been no problems. The directed go-around caused the loss of separation. The new procedures need to be refined so that a potential disaster does not occur.


Synopsis: Air Carrier on short final to LAS Runway 19L described a conflict event with departure traffic; the reporter alleging new mandatory go around procedures explained by ATC presented a safety concern as experienced in this instance.