Medium Transport; Low Wing; 2 Turbojet Eng
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 1.5
Communication Breakdown; Confusion; Distraction; Situational Awareness; Training / Qualification
ATC Issue All Types; Conflict Ground Conflict; Less Severe; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Incursion Runway
Air Traffic Control Issued New Clearance; Air Traffic Control Provided Assistance
Procedure; Aircraft; Human Factors
In this event; my role was the monitor of a developmental on the Local East position.  The trainee issued a clearance for an aircraft (Aircraft X) to cross the active departure runway with another aircraft holding in position (Aircraft Y).  After 20 or so seconds the Aircraft X had not started his taxi across the runway and it was wrongly assumed that the aircraft (Aircraft X) still holding short of the runway was another arrival aircraft instructed by the local west controller to hold short of runway 9L.  The trainee proceeded to clear Aircraft Y for takeoff while Aircraft X had not yet begun his taxi across the runway.  The pilot of Aircraft X heard the departure clearance and proceeded to hold short of the runway.  About 30 seconds after the departure clearance was issued; Aircraft X checked on the frequency stating that he was still holding short of the runway and I reiterated for the pilot to do so.There are no procedural recommendations for this event.  It was my responsibility as a trainer to monitor the trainees every transmission and ensure all rules are being adhered to.  I failed to realize that the trainee issued a departure clearance while another aircraft had not yet cleared the runway after being given a clearance to cross.  I must and will ensure that this situation never happens again.
We landed on runway 9R in PHL.  Tower instructed us to taxi on taxiways Sierra; Echo and to hold short of runway 9L.  Then we had been told to change frequency to 118.5 MHz. When we approach taxiway Echo; I heard that the airplane (Aircraft Y) that was on runway 9L requested one minute delay for departure clearance due to door malfunction.  When we approach holding line for runway 9L; I stopped the aircraft and check for the traffic that was holding position on the runway.At the same time ATC controller cleared us to cross runway 9L.  The clearance was confirmed and repeated to ATC by First Officer.  When I turned on all lights and add power (single engine taxi) to move the aircraft; I heard that Aircraft Y's pilots fixed the malfunction and that they were ready for takeoff on runway 9L.  ATC controller automatically cleared Aircraft Y for takeoff and probably forgot that he just cleared us to cross the same runway 5 seconds ago. I stopped the aircraft immediately just before crossing holding short line for runway 9L. Tower frequency became busy for another 10 sec at the same time.  As soon as we were able to transmit; First Officer reported us holding short of runway 9L.  Message was confirmed by ATC.  The rest of taxi was completed uneventfully.  I called PHL ATC and informed them about our situation.  After checking tapes ATC confirmed that we were cleared to cross runway 9L and at the same time other aircraft (Aircraft Y) was cleared for takeoff on 9L.
PHL Controllers and pilot of holding aircraft report of an almost runway incursion caused by the Developmental crossing an aircraft; then clearing an aircraft for takeoff.  The crossing aircraft held its position and did not enter the runway.