Small Aircraft
Flight Crew Commercial; Flight Crew Flight Instructor; Flight Crew Instrument
Flight Crew Last 90 Days 40; Flight Crew Total 4000; Flight Crew Type 2800
Communication Breakdown; Confusion; Distraction; Situational Awareness; Training / Qualification; Workload
ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Provided Assistance; Flight Crew Requested ATC Assistance / Clarification
Human Factors; Procedure
I was providing flight instruction to a student in the Van Nuys traffic pattern on runway 16L.  Winds were light and variable and the sky condition was clear with 10+ miles visibility.  We were communicating on 120.2 (which is a discrete frequency for traffic in the east pattern when the airport becomes busy.  119.3 is used for traffic west of the airport).  We had performed a touch and go on runway 16L and were climbing to pattern altitude (1800 feet MSL) on the upwind leg for left traffic.  As we turned left crosswind we received a traffic alert and visually spotted a low-wing aircraft about 1.0 miles on an extended downwind for 16L.  The controller had communicated '[Aircraft type] in left crosswind will be no problem for you' to some aircraft; but we weren't sure that it was this particular aircraft.  We were climbing through 1600 feet and the aircraft on TCAS was showing the pattern altitude of 1800 feet MSL.  I queried the controller about the aircraft now directly behind us at the same altitude and extremely close and there was silence.  Then the controller asked us if the aircraft was ahead of or behind us.  I said it was behind us.  He then made contact with the other aircraft and advised them of an aircraft (us) ahead and to his left.  The other aircraft said 'They are ahead and to my right and in sight.'  After we had landed; a few touch and go's later; I called the tower and spoke with a controller.  He stated that he was unaware of the situation (it had only happened 30 minutes prior) but would investigate.  He said that they were 'slammed busy' on the day and wouldn't be surprised if they had 300 IFR departures that day.  I said I appreciate a heavy workload; but it was obvious to us that the controller had lost track of us in that he had to ask us to identify which aircraft we were on the downwind.  He then stated that the other aircraft could have been a late handover from Burbank (it appeared unlikely as it appeared that the aircraft had made a direct downwind entry over the 405 from the Sepulveda Pass) or had contacted the tower late (this would be very late as they would have been miles into Class D inside the 405/101 interchange).  The controller further stated that this area is a regular 'problem' for the controllers.  This bit of anecdotal evidence was underscored by another instructor at the school where we originated the flight said the same thing had happened to her a month or so back.  I asked the controller if there was something we could have done to have prevented this.  His answer was 'No.'  Apparently there is a safety issue here and it should be addressed in some way.  I'm not sure of how the controllers track aircraft in the traffic pattern; but I believe it is with simple pen and paper.  Perhaps something a bit more exact/discrete like a transponder code?  I don't have the answer here.
Pilot reports of a busy day in the VFR traffic pattern at VNY airport. Aircraft confliction with traffic and the controller not knowing who was where; added to the pilot's traffic problem.