The most tragic outcome I ever heard about was at Camden NSW when the ATO cut the mixture on the right hand engine of a Duchess immediately the student (former B767 captain) had selected gear lever to up. This was at night or dusk. While during the briefing a couple of hours earlier at Bankstown the ATO (30,000 hours plus) told the student his intention was to conduct a simulated engine failure after take off at Camden, the student told the ATO he did not agree due night conditions on arrival. The ATO then agreed not to pull an engine. To cap it off, the ATO placed a map between the throttles and mixture lever as the student got airborne and then pulled the right hand mixture against his earlier agreement.
The student called for the ATO to reinstate the power quickly as he could not control the aircraft at such a low speed with windmilling prop. Soon after the Duchess clipped the top of a tree and stalled wheels up into rising ground and caught fire. The student survived but the ATO died of burns later.
A similar event but not tragic occurred in Victoria where an instructor conducting dual instruction failed the mixture on a student at 50 feet on take off in a Seneca? The student controlled the yaw correctly and continued the climb albeit with low gradient with gear still down . The speed fell below Blue Line in the confusion and the instructor told the student he should have landed straight head on the remaining runway length which is what the instructor had planned he should do. The student therefore did the bidding of the instructor and attempted to abandon the climb in order to put the aircraft back on the runway.
The instructor then grabbed the controls to salvage what was his stuff-up in the first place, and tried to land on the remaining length but landed very heavily and wiped out one wing. Both unhurt. As there was no property damage and no one hurt, ATSB did not investigate. The only report that went in to ATSB was by the instructor, in which he blamed the student for slow reaction and making the wrong decision to continue the single engine climb even though the student did well to control the aircraft until the instructor interfered.
The instructor thus self-exonerated himself for causing the problem in the first place. ATSB accepted the instructor's word for it without further comment leaving the student to wear the blame which was unfair. At no stage was either pilot interviewed by CASA or ATSB. And the student was never required to submit his version of the accident. I know all this because I saw the files...