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ZAB controller misjudged winds aloft when issuing vectors and direct navigation as a B737 overtakes a B757 while at cruise altitude.
| Attributes | |
| ACN | 534459 |
| Time | |
| Date | 200112 |
| Day | Sat |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| State Reference | NM |
| Altitude | msl single value : 31000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | artcc : zab.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | B757-200 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise : level |
| Route In Use | enroute : on vectors |
| Flight Plan | IFR |
| Aircraft 2 | |
| Controlling Facilities | artcc : zab.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | B737 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise : level |
| Route In Use | enroute : on vectors |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : radar |
| Qualification | controller : radar |
| Experience | controller limited radar : 1 controller radar : 11 |
| ASRS Report | 534459 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Events | |
| Anomaly | conflict : airborne less severe inflight encounter : weather inflight encounter other non adherence : published procedure non adherence : required legal separation |
| Independent Detector | atc equipment : conflict alert |
| Resolutory Action | none taken : detected after the fact |
| Consequence | faa : investigated |
| Miss Distance | horizontal : 24000 vertical : 1300 |
| Supplementary | |
| Problem Areas | Aircraft Flight Crew Human Performance Weather ATC Human Performance |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error |
Narrative:
Several aircraft were en route to phx, bunched up between gup and zun. Most were put on vectors and speed assignments for spacing. Aircraft had to cross sacho intersection (zun 242 degree radial, 40 DME) at FL310 and below. Winds were 310 degrees at 130 KTS. Aircraft Y was vectored behind aircraft X and slowed down for intrail spacing. Aircraft Y was then cleared direct sacho intersection. Aircraft Y gained speed and caught aircraft X. Conflict alert activated. Aircraft Y ws turned to avoid aircraft X. The situation was complex with action to space aircraft starting late. 2 aircraft were at FL390 at gup en route to phx. One of the aircraft is believed to have diverted to phx and was tied with the group. Ground speed varied from 385 KTS to 510 KTS for similar type aircraft. Some aircraft turned fast when given course changes, others turn much slower -- particularly airbus industries aircraft.
Original NASA ASRS Text
Title: ZAB CTLR MISJUDGED WINDS ALOFT WHEN ISSUING VECTORS AND DIRECT NAV AS A B737 OVERTAKES A B757 WHILE AT CRUISE ALT.
Narrative: SEVERAL ACFT WERE ENRTE TO PHX, BUNCHED UP BTWN GUP AND ZUN. MOST WERE PUT ON VECTORS AND SPD ASSIGNMENTS FOR SPACING. ACFT HAD TO CROSS SACHO INTXN (ZUN 242 DEG RADIAL, 40 DME) AT FL310 AND BELOW. WINDS WERE 310 DEGS AT 130 KTS. ACFT Y WAS VECTORED BEHIND ACFT X AND SLOWED DOWN FOR INTRAIL SPACING. ACFT Y WAS THEN CLRED DIRECT SACHO INTXN. ACFT Y GAINED SPD AND CAUGHT ACFT X. CONFLICT ALERT ACTIVATED. ACFT Y WS TURNED TO AVOID ACFT X. THE SIT WAS COMPLEX WITH ACTION TO SPACE ACFT STARTING LATE. 2 ACFT WERE AT FL390 AT GUP ENRTE TO PHX. ONE OF THE ACFT IS BELIEVED TO HAVE DIVERTED TO PHX AND WAS TIED WITH THE GROUP. GND SPD VARIED FROM 385 KTS TO 510 KTS FOR SIMILAR TYPE ACFT. SOME ACFT TURNED FAST WHEN GIVEN COURSE CHANGES, OTHERS TURN MUCH SLOWER -- PARTICULARLY AIRBUS INDUSTRIES ACFT.
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.