Major event time line

JUN - 3rd: Marietta, Georgia, overdose.
Later in the month, Tim Still calls AECL and asks if overdose by Therac-25 is possible.
JUL - 26th: Hamilton, Ontario, Canada, overdose; AECL notified and determines microswitch failure was the cause.
SEP - AECL makes changes to microswitch and notifies users of increased safety.
Independent consultant (for Hamilton Clinic) recommends potentiometer on turntable.
OCT - Georgia patient files suit against AECL and hospital.
NOV - 8th: Letter from CRPB to AECL asking for additional hardware interlocks and software changes.
DEC - Yakima, Washington, clinic overdose.

JAN - Attorney for Hamilton clinic requests that potentiometer be installed on turntable.
31st: Letter to AECL from Yakima reporting overdose possibility.
FEB - 24th: Letter from AECL to Yakima saying overdose was impossible and no other incidents had occurred.
MAR - 21st: Tyler, Texas, overdose. AECL notified; claims overdose impossible and no other accidents had occurred previously. AECL suggests hospital might have an electrical problem.
APR - 7th: Tyler machine put back in service after no electrical problem could be found.
11th: Second Tyler overdose. AECL again notified. Software problem found.
15th: AECL files accident report with FDA.
MAY - 2nd: FDA declares Therac-25 defective. Asks for CAP and proper renotification of Therac-25 users.
JUN - 13th: First version of CAP sent to FDA.
JUL - 23rd: FDA responds and asks for more information.
AUG - First user group meeting.
SEP - 26th: AECL sends FDA additional information.
OCT - 30th: FDA requests more information.
NOV - 12th: AECL submits revision of CAP.
DEC - Therac-20 users notified of a software bug.
11th: FDA requests further changes to CAP.
22nd: AECL submits second revision of CAP.

JAN - 17th: Second overdose at Yakima.
26th: AECL sends FDA its revised test plan.
FEB - Hamilton clinic investigates first accident and concludes there was an overdose.
3rd: AECL announces changes to Therac-25.
10th: FDA sends notice of adverse findings to AECL declaring Therac-25 defective under US law and asking AECL to notify customers that it should not be used for routine therapy. Health Protection Branch of Canada does the same thing. This lasts until August 1987.
MAR - Second user group meeting.
5th: AECL sends third revision of CAP to FDA.
APR - 9th: FDA responds to CAP and asks for additional information.
MAY - 1st: AECL sends fourth revision of CAP to FDA.
26th: FDA approves CAP subject to final testing and safety analysis.
JUN - 5th: AECL sends final test plan and draft safety analysis to FDA.
JUL - Third user group meeting.
21st: Fifth (and final) revision of CAP sent to FDA.

JAN - 29th: Interim safety analysis report issued.
NOV - 3rd: Final safety analysis report issued.