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37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
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Air carrier X descent through occupied altitude had less than standard separation from air carrier Y. System error.
| Attributes | |
| ACN | 190231 |
| Time | |
| Date | 199109 |
| Day | Sat |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : atr |
| State Reference | DE |
| Altitude | msl bound lower : 16300 msl bound upper : 17000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | Any Unknown or Unlisted Aircraft Manufacturer |
| Flight Phase | descent other |
| Route In Use | enroute : direct enroute airway : zdc |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | common carrier : air carrier |
| Make Model Name | Any Unknown or Unlisted Aircraft Manufacturer |
| Flight Phase | cruise other |
| Route In Use | enroute : direct |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : radar |
| Qualification | controller : radar |
| Experience | controller military : 5 controller non radar : 3 controller radar : 1 |
| ASRS Report | 190231 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | conflict : airborne less severe non adherence : published procedure non adherence : required legal separation |
| Independent Detector | other controllera |
| Resolutory Action | controller : issued new clearance other |
| Consequence | faa : investigated |
| Miss Distance | horizontal : 18000 vertical : 300 |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error |
Narrative:
Air carrier X descending to FL180 with no crossing restriction per SOP checked on and was immediately issued a clearance to 140 with altimeter setting and given leaving 160, cleared direct to ATR VORTAC. Air carrier X was advised of slower traffic northbound at 170 which was air carrier Y leaving FL180 15 mi from air carrier Y. Air carrier X was issued the traffic and given an increased descent rate. Air carrier Y checked on at 170 and for added separation assurance, turned right heading 095 degree and air carrier X right heading 300 degree 8-10 mi from conflict point. Air carrier X mode C displayed 163. When asked if level 160, air carrier X delayed his response and said 300 ft to go. For the next 8-10 mi, mode C on air carrier X displayed 163, through confliction point with air carrier Y during this time frame, military Z popped up 5-6 mi west of small transport FL210 descending to 110 also in conflict with air carrier X descending to 140. Air carrier X was reissued an altitude of 160 versus 140 to avoid confliction with military Z. Military Z was positioned 15 mi ahead of air carrier X crossing left to right. Communications were not established with military Z. Thereby causing air carrier X to be issued the amended altitude of 160, thereby causing air carrier X to stop descent early.
Original NASA ASRS Text
Title: ACR X DSCNT THROUGH OCCUPIED ALT HAD LTSS FROM ACR Y. SYS ERROR.
Narrative: ACR X DSNDING TO FL180 WITH NO XING RESTRICTION PER SOP CHKED ON AND WAS IMMEDIATELY ISSUED A CLRNC TO 140 WITH ALTIMETER SETTING AND GIVEN LEAVING 160, CLRED DIRECT TO ATR VORTAC. ACR X WAS ADVISED OF SLOWER TFC NBOUND AT 170 WHICH WAS ACR Y LEAVING FL180 15 MI FROM ACR Y. ACR X WAS ISSUED THE TFC AND GIVEN AN INCREASED DSCNT RATE. ACR Y CHKED ON AT 170 AND FOR ADDED SEPARATION ASSURANCE, TURNED R HDG 095 DEG AND ACR X R HDG 300 DEG 8-10 MI FROM CONFLICT POINT. ACR X MODE C DISPLAYED 163. WHEN ASKED IF LEVEL 160, ACR X DELAYED HIS RESPONSE AND SAID 300 FT TO GO. FOR THE NEXT 8-10 MI, MODE C ON ACR X DISPLAYED 163, THROUGH CONFLICTION POINT WITH ACR Y DURING THIS TIME FRAME, MIL Z POPPED UP 5-6 MI W OF SMT FL210 DSNDING TO 110 ALSO IN CONFLICT WITH ACR X DSNDING TO 140. ACR X WAS REISSUED AN ALT OF 160 VERSUS 140 TO AVOID CONFLICTION WITH MIL Z. MIL Z WAS POSITIONED 15 MI AHEAD OF ACR X XING L TO R. COMS WERE NOT ESTABLISHED WITH MIL Z. THEREBY CAUSING ACR X TO BE ISSUED THE AMENDED ALT OF 160, THEREBY CAUSING ACR X TO STOP DSCNT EARLY.
Data retrieved from NASA's ASRS site as of July 2007 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.