Small aircraft X non adherence to ATC instructions had near midair collision with small aircraft Y i...

Attributes
ACN	206226
Time
Date	199203
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : pie
State Reference	FL
Altitude	msl bound lower : 700 msl bound upper : 700
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : pie
Operator	general aviation : instructional
Make Model Name	Small Aircraft, High Wing, 1 Eng, Fixed Gear
Flight Phase	descent : approach
Route In Use	approach : visual
Flight Plan	None
Aircraft 2
Operator	general aviation : instructional
Make Model Name	Small Aircraft, High Wing, 1 Eng, Fixed Gear
Flight Phase	descent : approach
Route In Use	approach : visual
Flight Plan	None
Person 1
Affiliation	government : faa
Function	controller : local
Qualification	controller : non radar
ASRS Report	206226
Person 2
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : private pilot : instrument
Events
Anomaly	conflict : nmac non adherence : clearance
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 100 vertical : 100
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Small aircraft X had been following small aircraft Y in the pattern. I observed small aircraft X on a left base that appeared to close. I asked the pilot if he had small aircraft Y traffic that he was following in sight, he responded affirmative. I turned to see other traffic then looked back and saw small aircraft X slightly higher and within 100 ft of small aircraft Y. I told small aircraft X to start an immediate right turn. (There was traffic following him on the left downwind). Small aircraft X turned left. I observed the turn and issued an evasive turn (360) to an aircraft on the downwind. I then told small aircraft X that I observed his left turn, issued traffic and instructed small aircraft X to enter a left base for runway 35R (they had been on runway 35L). Small aircraft X was cleared to land and taxied to the ramp. Had I not turned small aircraft X there is no doubt in my mind that they would have hit. The pilot came to the tower later to apologize. He said he was working on an instrument rating and he thought (when he turned base) that small aircraft Y he had seen landed on runway 35R.

Original NASA ASRS Text

Title: SMA X NON ADHERENCE TO ATC INSTRUCTIONS HAD NMAC WITH SMA Y IN ATA.

Narrative: SMA X HAD BEEN FOLLOWING SMA Y IN THE PATTERN. I OBSERVED SMA X ON A L BASE THAT APPEARED TO CLOSE. I ASKED THE PLT IF HE HAD SMA Y TFC THAT HE WAS FOLLOWING IN SIGHT, HE RESPONDED AFFIRMATIVE. I TURNED TO SEE OTHER TFC THEN LOOKED BACK AND SAW SMA X SLIGHTLY HIGHER AND WITHIN 100 FT OF SMA Y. I TOLD SMA X TO START AN IMMEDIATE R TURN. (THERE WAS TFC FOLLOWING HIM ON THE L DOWNWIND). SMA X TURNED L. I OBSERVED THE TURN AND ISSUED AN EVASIVE TURN (360) TO AN ACFT ON THE DOWNWIND. I THEN TOLD SMA X THAT I OBSERVED HIS L TURN, ISSUED TFC AND INSTRUCTED SMA X TO ENTER A L BASE FOR RWY 35R (THEY HAD BEEN ON RWY 35L). SMA X WAS CLRED TO LAND AND TAXIED TO THE RAMP. HAD I NOT TURNED SMA X THERE IS NO DOUBT IN MY MIND THAT THEY WOULD HAVE HIT. THE PLT CAME TO THE TWR LATER TO APOLOGIZE. HE SAID HE WAS WORKING ON AN INST RATING AND HE THOUGHT (WHEN HE TURNED BASE) THAT SMA Y HE HAD SEEN LANDED ON RWY 35R.

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.

Small aircraft X non adherence to ATC instructions had near midair collision with small aircraft Y in air traffic area.