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Phx tower controller experienced operational error when sufficient time interval was not used with successive B757 departure aircraft.
| Attributes | |
| ACN | 656402 |
| Time | |
| Date | 200505 |
| Place | |
| Locale Reference | airport : phx.airport |
| State Reference | AZ |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tower : phx.tower |
| Operator | common carrier : air carrier |
| Make Model Name | B757 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Plan | IFR |
| Aircraft 2 | |
| Controlling Facilities | tower : phx.tower |
| Operator | common carrier : air carrier |
| Make Model Name | B757 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | climbout : takeoff climbout : initial ground : takeoff roll |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : local |
| Qualification | controller : radar controller : military |
| ASRS Report | 656402 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : single pilot oversight : pic |
| Events | |
| Anomaly | non adherence : required legal separation |
| Independent Detector | other controllera |
| Resolutory Action | none taken : detected after the fact |
| Supplementary | |
| Problem Areas | ATC Human Performance |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error |
Narrative:
Runway 25L and runway 25R are less than 2500 ft apart. Runway 25L had a displaced threshold; making all of those departures intersection departures; because both runways are considered as one for wake turbulence separation. I departed a B757 from runway 25R. I put a second B757 in position for departure on runway 25L. The ATC handbook states that the second aircraft does not start takeoff roll until at least 3 mins after the other B757 has taken off. The traffic picture was moderate and complex. I departed the second B757; 1 1/2 mins after the first aircraft. At the time I was thinking like aircraft; all I need is 4 mi radar separation. When the second aircraft was airborne; radar separation between both aircraft was 4.75 mi and 1700 ft vertical. Human performance consideration: I was aware of the 3 min rule. However; at the time what stuck in my mind was like aircraft and performance; different departure sids and I was going to have a minimum of 4 mi between 2 B757's.
Original NASA ASRS Text
Title: PHX TWR CTLR EXPERIENCED OPERROR WHEN SUFFICIENT TIME INTERVAL WAS NOT USED WITH SUCCESSIVE B757 DEP ACFT.
Narrative: RWY 25L AND RWY 25R ARE LESS THAN 2500 FT APART. RWY 25L HAD A DISPLACED THRESHOLD; MAKING ALL OF THOSE DEPS INTXN DEPS; BECAUSE BOTH RWYS ARE CONSIDERED AS ONE FOR WAKE TURB SEPARATION. I DEPARTED A B757 FROM RWY 25R. I PUT A SECOND B757 IN POS FOR DEP ON RWY 25L. THE ATC HANDBOOK STATES THAT THE SECOND ACFT DOES NOT START TKOF ROLL UNTIL AT LEAST 3 MINS AFTER THE OTHER B757 HAS TAKEN OFF. THE TFC PICTURE WAS MODERATE AND COMPLEX. I DEPARTED THE SECOND B757; 1 1/2 MINS AFTER THE FIRST ACFT. AT THE TIME I WAS THINKING LIKE ACFT; ALL I NEED IS 4 MI RADAR SEPARATION. WHEN THE SECOND ACFT WAS AIRBORNE; RADAR SEPARATION BTWN BOTH ACFT WAS 4.75 MI AND 1700 FT VERT. HUMAN PERFORMANCE CONSIDERATION: I WAS AWARE OF THE 3 MIN RULE. HOWEVER; AT THE TIME WHAT STUCK IN MY MIND WAS LIKE ACFT AND PERFORMANCE; DIFFERENT DEP SIDS AND I WAS GOING TO HAVE A MINIMUM OF 4 MI BTWN 2 B757'S.
Data retrieved from NASA's ASRS site as of January 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.