Medium Transport; Low Wing; 2 Turboprop Eng
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 1.75
Communication Breakdown; Distraction; Situational Awareness; Troubleshooting; Confusion
ATC Issue All Types; Conflict Airborne Conflict; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
Procedure; Human Factors
At DEN Tower we have a continuing procedure problem with RNAV departures.  The RNAV procedures off of parallel runways will actually turn aircraft into each other.  Management has implemented local procedures to try and mitigate the risk.  But time and time again; the mitigations do not work.  The newest mitigation procedure is to add the phrase 'For traffic' when issuing a heading to a pilot expecting to depart on the RNAV.  Which is what I did and it is still not enough to jar the pilot into not flying the RNAV procedure that will fly them into another airplane.  I instructed Aircraft X; 'For traffic; fly heading 335; RWY34L cleared for takeoff.'  I also instructed Aircraft Y 'RNAV to NUGGS; RWY34R; Cleared for takeoff.'  Aircraft X engaged the RNAV to fly to CAAZZ; which turned him close to Aircraft Y.  I don't know how close they got; but I estimate between 1.5-2.5 miles laterally.  I cannot remember how close they got in altitude.  Later when Aircraft X called the tower; the pilot said he was thinking RNAV all the way.  This pilot is not the first and won't be the last to fly the RNAV procedure when issued a heading.  They have an expectation bias and even the extra phrase 'For traffic' will never ensure they fly the assigned heading rather than the RNAV procedure.  After listening to the tapes; I found that I did not ensure a readback of the heading assigned as our local procedure requires.  The pilot only readback RWY34L cleared for takeoff.  This is another mitigation required here at DEN due to the flawed RNAV procedures.  The RNAV procedures must be fixed.The RNAV departure procedures at DEN must be stopped in their current form.  We have had very very close calls of aircraft almost hitting each other due to the design of the RNAV procedure.  DEN Tower has been trying to work with DEN TRACON on an interim vectors off the ground procedures until metroplex can redesign the departure RNAV procedures into vectors off the ground.  Both are taking too long to fix.  It seems to me that TRACON considers this a DEN Tower problem and is unwilling to work with Tower in any way.  This is a huge safety issue that everyone needs to work towards eliminating.  No more mitigations.  Stop RNAV departures at DEN.  Don't let two airplanes collide for the agency to make the necessary change.  Do it now.  Pull all the previous incident reports.  This has happened before and will continue to happen.
DEN Tower Controller describes a situation relating to RNAV departure procedures that have aircraft turning into each other.