Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 3
Confusion; Communication Breakdown; Distraction; Situational Awareness
Conflict Airborne Conflict; Deviation - Speed All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
Aircraft; Human Factors; Procedure
A trainee was training on LC1 with a supervisor.  LA1 was staffed with a local safety council member which is why I do not want them to be a de-identified version because both of the controllers suggested that the following situation was not a safety issue nor involved them breaking any rules when I brought it up to them before they departed both aircraft.  Aircraft X departed rwy16R on an IFR departure to take them southwest-bound.  A few seconds later; the trainee departed the much faster Aircraft Y on rwy16L southeast bound.  I had brought to their attention that Aircraft Y will catch up to the Aircraft X before the point where both aircraft are to make their turns per the SID (the VNY 2.2DME @ 1750 MSL).  Despite this; the IFR Aircraft Y was only issued traffic later once airborne and still drifted close to and overtook the other Aircraft X that had departed off the parallel.  Neither the supervisor training; CPC-DEV; or LA1 (LSC member) seemed to care and only watched it play out to a very unsafe situation.  The only way to prevent a collision would have been to take one aircraft off of the SID because they failed to consider aircraft performance with the IFR departures.  All three of the people working the runways thought they could use visual separation (controller applied) as a way to provide separation before the SID turn. My role was me working ground control and watching this scenario.  I tried to advise the locals of the performance situation that would lead to the extremely close call for traffic.  It was poor management of traffic when the only two operations pending was the departure of those two IFR aircraft.Two small IFR propeller aircraft departing separate runways to different directions (that will not cross flight paths) does not guarantee separation.  Controllers should be taught to launch successive IFRS with spacing that does not involve both reaching the VNY 2.2DME simultaneously and then turning different directions.
VNY Ground Controller describes a loss of separation with a faster aircraft over taking a slower aircraft on departure.