A319
Air Traffic Control Time Certified In Pos 1 (yrs) 20
ATC Issue All Types; Conflict Airborne Conflict; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance
Human Factors; Procedure
VFR day. Departing runways 33L/R. Aircraft X turn left heading 110; Runway 33L Cleared For Take Off (CFT). He went wide so; I waited a bit longer to clear my next departure. Aircraft Y turn left heading 110; Runway 33L CFT. Aircraft Y turned a bit tighter but not much. I continued working other traffic while keeping an eye on these two aircraft. I was watching both visually (out the window; clear day) and on radar. Aircraft X was told to contact departure.It never appeared to me that radar separation would be lost or that these two aircraft were in an unsafe proximity to each other. However; I wanted the aircraft to be in a nice straight line out the gate. I issued Aircraft Y to fly heading 180 to widen him out a bit behind Aircraft X. No response from Aircraft Y. I tried him again and still; no response. I then called the departure controller working the sector and gave him control on contact with Aircraft Y reference Aircraft X. I re-attempted to contact Aircraft Y both on tower frequency and guard. Still no response. Approach finally called back and said he had Aircraft Y on frequency. The departure controller then asked if I had the two aircraft visually out the window; in which I replied yes. Not sure what happened on pilot's side with Aircraft Y.
I received a call from my program manager about a safety report filed by a controller in IAH departure. In this call I was told that it was a loss of separation and possible pilot error. To my knowledge we followed all ATC instructions and the flight was uneventful. I do remember one of the controllers seemed a little saturated and asked our altitude. Clear communication from ATC to crew and crew to ATC!
Houston Tower Controller and air carrier pilot reported a possible pilot deviation that led to a loss of separation with previous departure; however the pilot was unaware of any problem.