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Flight crew of a B727, while in descent, observed another aircraft target on TCASII converging perpendicular to their flight path at a high rate of descent. Even though the other aircraft passed above at 2000 ft, it caused them alarm to think that if either aircraft had changed their rate of descent, a potential collision was possible.
| Attributes | |
| ACN | 461776 |
| Time | |
| Date | 200001 |
| Day | Sun |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| State Reference | FO |
| Altitude | msl single value : 20000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | B727 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | descent : vacating altitude |
| Route In Use | arrival : on vectors |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | common carrier : air carrier |
| Make Model Name | B737 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | descent : vacating altitude |
| Route In Use | arrival : on vectors |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : flight engineer pilot : atp |
| Experience | flight time last 90 days : 100 flight time total : 6000 flight time type : 2000 |
| ASRS Report | 461776 |
| Person 2 | |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | conflict : airborne less severe non adherence : required legal separation |
| Independent Detector | aircraft equipment : tcas other flight crewa other flight crewb |
| Resolutory Action | none taken : anomaly accepted |
| Consequence | Other |
| Miss Distance | horizontal : 0 vertical : 2000 |
| Supplementary | |
| Problem Areas | ATC Human Performance Flight Crew Human Performance |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | other |
Narrative:
Descending into puj, center asked us our descent rate. I informed the controller it was 3500 FPM. No other instructions or advisories were given. A few moments later, a target appeared on our TCASII that was converging with us perpendicularly. The target was also in a descent and later learned he was cleared through our altitude. The traffic was a B747 that passed directly over us with a varying 2000 ft separation. Although there was no incident this time, there easily could have been a midair collision if one of us changed our rate of descent and we didn't have TCASII. 90% of our 220+ fleet of jets do not have TCASII installed because they fly cargo. Our airline operates worldwide and it's only a matter of time before we are involved in a midair event because we don't have TCASII installed. The FARS need to be changed immediately to include cargo jets requiring TCASII.
Original NASA ASRS Text
Title: FLC OF A B727, WHILE IN DSCNT, OBSERVED ANOTHER ACFT TARGET ON TCASII CONVERGING PERPENDICULAR TO THEIR FLT PATH AT A HIGH RATE OF DSCNT. EVEN THOUGH THE OTHER ACFT PASSED ABOVE AT 2000 FT, IT CAUSED THEM ALARM TO THINK THAT IF EITHER ACFT HAD CHANGED THEIR RATE OF DSCNT, A POTENTIAL COLLISION WAS POSSIBLE.
Narrative: DSNDING INTO PUJ, CTR ASKED US OUR DSCNT RATE. I INFORMED THE CTLR IT WAS 3500 FPM. NO OTHER INSTRUCTIONS OR ADVISORIES WERE GIVEN. A FEW MOMENTS LATER, A TARGET APPEARED ON OUR TCASII THAT WAS CONVERGING WITH US PERPENDICULARLY. THE TARGET WAS ALSO IN A DSCNT AND LATER LEARNED HE WAS CLRED THROUGH OUR ALT. THE TFC WAS A B747 THAT PASSED DIRECTLY OVER US WITH A VARYING 2000 FT SEPARATION. ALTHOUGH THERE WAS NO INCIDENT THIS TIME, THERE EASILY COULD HAVE BEEN A MIDAIR COLLISION IF ONE OF US CHANGED OUR RATE OF DSCNT AND WE DIDN'T HAVE TCASII. 90% OF OUR 220+ FLEET OF JETS DO NOT HAVE TCASII INSTALLED BECAUSE THEY FLY CARGO. OUR AIRLINE OPERATES WORLDWIDE AND IT'S ONLY A MATTER OF TIME BEFORE WE ARE INVOLVED IN A MIDAIR EVENT BECAUSE WE DON'T HAVE TCASII INSTALLED. THE FARS NEED TO BE CHANGED IMMEDIATELY TO INCLUDE CARGO JETS REQUIRING TCASII.
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.