Citation X (C750)
Other / Unknown
ATC Issue All Types; Conflict Airborne Conflict
Flight Crew Took Evasive Action; Flight Crew FLC complied w / Automation / Advisory
Airspace Structure; Human Factors; Procedure
Right base for 16R at 2;000 FT. Tower pointed out C172 traffic 12:00; 2 miles at 2;500 FT (in sight). Then; helicopter 2:00 1;500 FT (never in sight). Shortly afterward we received the Climb RA; TCAS climb announced to ATC. Moments later we received the stop climb and descend; then maintain VS. PFDs showed red lines above and below with the target box in the middle. ATC advised of dual RAs. No comments or apology from tower. TCAS RAs were followed and ATC was notified. Suggestions; ATC knew of our arrival (IFR) and should have planned accordingly. Tower should not have attempted to thread us through two opposing aircraft who were 500 FT above and 500 FT below our planned path. ATC had told us they would notify us when to turn base. When after we made the base turn; were received the RAs. ATC should have provided more space between us and the other aircraft. ATC could have also held them at a greater distance.
We were on right base to 16R at 2;000 FT MSL. Tower advised us of traffic above us 500 FT; a Cessna 172. We had this traffic in sight. We also had a helicopter 500 FT below us which we never saw. Shortly after traffic was given by tower we received a Climb RA; TCAS which we complied with and advised ATC about. Moments later we received a Stop Climb and Descend RA followed by Maintain VS. PFDs showed red lines above and below with the target box in the middle. ATC was advised of dual RAs. No comments or apology was given from the Tower. Suggestions; I think there was little the crew could do to prevent this. I believe it is a matter of ATC not sandwiching aircraft between two other aircraft with 500 FT separation. We were looking for our traffic as advised by ATC but never saw the helicopter which started the whole RA alert process. I was very happy to have had the Cessna 172 in sight before the RAs started as I new his location.
Corporate jet inbound to VNY experienced a TCAS RA with issued VFR traffic both above and below by 500 feet; the reporter suggesting more separation be afforded by ATC is this circumstance.