M20P pilot and a light twin had an near midair collision in nct class east.

Attributes
ACN	579218
Time
Date	200304
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : smf.airport
State Reference	CA
Altitude	msl single value : 2000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : nct.tracon
Operator	general aviation : personal
Make Model Name	M-20 J (201)
Operating Under FAR Part	Part 91
Flight Phase	descent : approach
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : nct.tracon
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise : level
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : multi engine pilot : commercial pilot : cfi pilot : private pilot : instrument
Experience	flight time last 90 days : 20 flight time total : 2000 flight time type : 200
ASRS Report	579218
Person 2
Function	flight crew : single pilot
Events
Anomaly	conflict : nmac non adherence : far non adherence : published procedure other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : collision warning system other controllera other flight crewa other other : pax 4
Resolutory Action	controller : issued advisory flight crew : took evasive action none taken : detected after the fact other
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 200 vertical : 0
Supplementary
Problem Areas	ATC Human Performance FAA Flight Crew Human Performance
Primary Problem	Ambiguous
Situations
ATC Facility	procedure or policy : nct.tracon staffing : nct.tracon

Narrative:

ATC descended us to 2000 ft MSL with assigned heading. Collision avoidance alarm sounded. Passenger warned of nearby aircraft. I got visual on the aircraft as we were on collision course. I banked 50 degrees to left and dove down. I mentioned to ATC that collision was avoided, and that I believed we were now in front of the other aircraft. I asked him if the twin was gaining on us. He paused and said something to the effect that he called traffic, and I was at the wrong altitude. I mentioned to him I dove down to avoid the other aircraft. He then told me to stay at 2000 ft, and notify him of airport in sight. I called airport in sight. He said 'cleared for the visual approach, make right downwind for runway 30. I descended for the downwind. At 1500 ft he asked altitude, and said he told me to 'maintain 2000 ft' until established on the downwind.' ATC very busy at the time. I climbed to 2000 ft and was turned over to tower. Contributing factor was that ATC was over worked and controling too many airplanes. He was talking very fast and often times hard to understand. Pilot needs to be clear on all clrncs. What I heard, and what he said, were 2 different things.

Original NASA ASRS Text

Title: M20P PLT AND A LIGHT TWIN HAD AN NMAC IN NCT CLASS E.

Narrative: ATC DSNDED US TO 2000 FT MSL WITH ASSIGNED HDG. COLLISION AVOIDANCE ALARM SOUNDED. PAX WARNED OF NEARBY ACFT. I GOT VISUAL ON THE ACFT AS WE WERE ON COLLISION COURSE. I BANKED 50 DEGS TO L AND DOVE DOWN. I MENTIONED TO ATC THAT COLLISION WAS AVOIDED, AND THAT I BELIEVED WE WERE NOW IN FRONT OF THE OTHER ACFT. I ASKED HIM IF THE TWIN WAS GAINING ON US. HE PAUSED AND SAID SOMETHING TO THE EFFECT THAT HE CALLED TFC, AND I WAS AT THE WRONG ALT. I MENTIONED TO HIM I DOVE DOWN TO AVOID THE OTHER ACFT. HE THEN TOLD ME TO STAY AT 2000 FT, AND NOTIFY HIM OF ARPT IN SIGHT. I CALLED ARPT IN SIGHT. HE SAID 'CLRED FOR THE VISUAL APCH, MAKE R DOWNWIND FOR RWY 30. I DSNDED FOR THE DOWNWIND. AT 1500 FT HE ASKED ALT, AND SAID HE TOLD ME TO 'MAINTAIN 2000 FT' UNTIL ESTABLISHED ON THE DOWNWIND.' ATC VERY BUSY AT THE TIME. I CLBED TO 2000 FT AND WAS TURNED OVER TO TWR. CONTRIBUTING FACTOR WAS THAT ATC WAS OVER WORKED AND CTLING TOO MANY AIRPLANES. HE WAS TALKING VERY FAST AND OFTEN TIMES HARD TO UNDERSTAND. PLT NEEDS TO BE CLR ON ALL CLRNCS. WHAT I HEARD, AND WHAT HE SAID, WERE 2 DIFFERENT THINGS.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.