Date: 201411
Local time of day: 1201-1800
Location: ONT.Airport, CA
Light: Daylight
Aircraft: Large Transport
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Climb
Airspace: Class C ONT
ATC / advisory: Tower ONT
Second aircraft: Small Transport; Low Wing; 2 Turboprop Eng
Reporter organization: Government
Reporter function: Instructor; Local
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Communication Breakdown; Confusion
Second reporter function: Local; Trainee
Anomaly: ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Separated Traffic
Contributing factors: Human Factors; Procedure
Primary problem: Procedure

Narrative: We had Aircraft X holding short of [Runway] 8L flashing for release. There was a carrier on final for [Runway] 26L who had previously arrived from the south and vectored outside of 10 mile final for approach. There was also Aircraft Y 15 miles south at 5;000 feet on a north easterly heading on approach. SoCal released Aircraft X with a 4000 ft. restriction reference Aircraft Y. We had to wait for the aircraft on final to touch down [on Runway] 26L. When the aircraft was short final we lined up Aircraft X on Runway 8L. Aircraft Y was still at 5;000 feet heading north-eastbound. We cleared Aircraft X for takeoff and then we noticed that Aircraft Y turn a seven mile base for [Runway] 26L. Immediately we got on the line with SoCal and notified them that Aircraft Y was going north through the final and that they were going to be switched back to them reference the departure and an additional carrier arrival. Opposite direction arrivals/departure procedures entail that the departure has to be in their turn before the arrival reaches 10 mile final. SoCal released our Aircraft X departure with the restriction reference Aircraft Y and then turn him inside the 10 mile final to try and get Aircraft Y in before another carrier. I'm not sure if they forgot they released Aircraft X or assumed we weren't departing Aircraft X before Aircraft Y. We also were working under the assumption that since they gave us an altitude reference Aircraft Y and released the aircraft that they would not turn Aircraft Y in for final reference the 10 mile opposite direction rule. I recommend that there be clarification to the opposite direction order. The order says 10 mile radius but operationally we always use established final for the departure/arrival. If they do not intend for it to be 10 mile final and want a 10 mile radius there needs to be clarification from management on this. The majority of both SoCal and ONT CPCs (Certified Professional Controller) understand work on the premise the aircraft has to be in their turn before the aircraft reaches 10 mile final. Also if it is radius versus final their needs to be an altitude limit as well because we wouldn't be able to clear aircraft within the 10 mile radius even if they are at 15;000 ft. I also recommend that the inter-facility coordination be improved. If SoCal questioned the order of the arrival/departure sequence or whether they could get Aircraft Y in before the Aircraft X departure; they should have initiated coordination with us. SoCal did not ensure separation between the departure they released [and] with the arrival they cut in; inside the 10 mile restriction. If SoCal wanted to put Aircraft Y before the departure they released reference Aircraft Y; they should have called and canceled the release on Aircraft Y.


Second narrative: [Report narrative contained no additional information]


Synopsis: ONT Tower Controllers describe a situation where an opposite direction arrival is turned in towards the airport while a approved departure is released; losing separation with the arrival.