2 small transport aircraft, same company, have near midair collision when sequenced incorrectly in p...

Attributes
ACN	135473
Time
Date	199002
Day	Fri
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : oak
State Reference	CA
Altitude	msl bound lower : 1000 msl bound upper : 1000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tower : oak2
Operator	common carrier : air taxi
Make Model Name	Small Transport, Low Wing, 2 Recip Eng
Flight Phase	descent : approach other
Flight Plan	VFR
Aircraft 2
Operator	common carrier : air taxi
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	descent : approach other
Person 1
Affiliation	company : air taxi
Function	flight crew : single pilot
Qualification	pilot : cfi pilot : atp pilot : instrument pilot : commercial
Experience	flight time last 90 days : 300 flight time total : 2700 flight time type : 150
ASRS Report	135473
Person 2
Affiliation	government : faa
Function	controller : local
Qualification	controller : non radar
Events
Anomaly	conflict : nmac other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 100 vertical : 100
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Deviation

Narrative:

Aircraft X cleared to land 27R. Company aircraft Y cleared for 27L. I was told company Y was on base. As I executed base, nearly collided with company on downwind abeam #'south. I left the immediate area toward green tank due to ATC confusion. Talked to tower on ground. Callback conversation with reporter revealed the following: reporter clarified positions of aircraft before and at time of near midair collision. Reporter's aircraft X was on right downwind for 27R. Aircraft Y had also been placed on a right downwind, but cleared for 27L and was flying inboard of X and, as it turned out, somewhat behind him. When X turned base with Y still on downwind, the 2 aircraft converged directly and came very close. X turned away from the pattern toward the green tank and Y continued pattern and landed on 27L as cleared. X was vectored back to pattern and landed routinely. Reporter phoned tower after landing and said that controller admitted having lost the picture, thinking Y ahead of X and already on base, and apologized for error. Not known if any enforcement action being taken.

Original NASA ASRS Text

Title: 2 SMT ACFT, SAME COMPANY, HAVE NMAC WHEN SEQUENCED INCORRECTLY IN PATTERN BY ATC.

Narrative: ACFT X CLRED TO LAND 27R. COMPANY ACFT Y CLRED FOR 27L. I WAS TOLD COMPANY Y WAS ON BASE. AS I EXECUTED BASE, NEARLY COLLIDED WITH COMPANY ON DOWNWIND ABEAM #'S. I LEFT THE IMMEDIATE AREA TOWARD GREEN TANK DUE TO ATC CONFUSION. TALKED TO TWR ON GND. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: RPTR CLARIFIED POSITIONS OF ACFT BEFORE AND AT TIME OF NMAC. REPORTER'S ACFT X WAS ON RIGHT DOWNWIND FOR 27R. ACFT Y HAD ALSO BEEN PLACED ON A RIGHT DOWNWIND, BUT CLRED FOR 27L AND WAS FLYING INBOARD OF X AND, AS IT TURNED OUT, SOMEWHAT BEHIND HIM. WHEN X TURNED BASE WITH Y STILL ON DOWNWIND, THE 2 ACFT CONVERGED DIRECTLY AND CAME VERY CLOSE. X TURNED AWAY FROM THE PATTERN TOWARD THE GREEN TANK AND Y CONTINUED PATTERN AND LANDED ON 27L AS CLRED. X WAS VECTORED BACK TO PATTERN AND LANDED ROUTINELY. RPTR PHONED TWR AFTER LNDG AND SAID THAT CTLR ADMITTED HAVING LOST THE PICTURE, THINKING Y AHEAD OF X AND ALREADY ON BASE, AND APOLOGIZED FOR ERROR. NOT KNOWN IF ANY ENFORCEMENT ACTION BEING TAKEN.

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.

2 small transport aircraft, same company, have near midair collision when sequenced incorrectly in pattern by ATC.