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37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
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Atx X descent through occupied altitude while on radar vector had less than standard separation from aircraft Y. System error.
| Attributes | |
| ACN | 214802 |
| Time | |
| Date | 199207 |
| Day | Wed |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : fgt |
| State Reference | MN |
| Altitude | msl bound lower : 3000 msl bound upper : 5000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : msp |
| Operator | common carrier : air taxi |
| Make Model Name | Small Aircraft, Low Wing, 2 Eng, Retractable Gear |
| Flight Phase | descent other |
| Route In Use | enroute : on vectors |
| Flight Plan | IFR |
| Aircraft 2 | |
| Make Model Name | Any Unknown or Unlisted Aircraft Manufacturer |
| Flight Phase | cruise other |
| Route In Use | enroute : direct |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | Other |
| Function | flight crew : single pilot |
| Qualification | pilot : cfi pilot : atp |
| Experience | flight time last 90 days : 140 flight time total : 3000 flight time type : 600 |
| ASRS Report | 214802 |
| Person 2 | |
| Affiliation | Other |
| Function | flight crew : single pilot |
| Qualification | pilot : instrument pilot : commercial |
| Events | |
| Anomaly | conflict : airborne less severe non adherence : published procedure non adherence : required legal separation |
| Independent Detector | other controllera other flight crewa |
| Resolutory Action | controller : issued new clearance other |
| Consequence | Other |
| Miss Distance | horizontal : 12000 vertical : 0 |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error |
Narrative:
Atx X received a clearance to 4000 ft, with assigned heading 220 degrees. While descending through 5000 ft, my clearance was amended to descend and maintain 3000 ft. I was then asked if I could expedite my descent. Since 500 FPM is normally the maximum descent rate in an unpressurized aircraft with passenger, I told the controller I would be unable to expedite the descent. I was then assigned a heading of 180 degrees, and at this point was passing through approximately 4300 ft. Before I could complete this turn, I was told to turn further left to a heading of 160 degrees. I was then informed aircraft Y at my 2 O'clock and 2 mi, sebound, altitude 4000 ft and was told to expedite my descent. Since I was also approaching 4000 ft at this time, and since the turn put the other aircraft Y in the blind spot under my wing, I was forced to increase to 1000 FPM descent briefly to avoid the conflict. This situation probably could have been avoided had the approach controller halted my descent temporarily until I was clear of aircraft Y, given me an earlier vector to clear the traffic while continuing my descent, or informed me of the traffic earlier, when I could have seen it. I think part of the problem is also that some controllers are not aware of or do not understand performance limitations of unpressurized aircraft and blind spots that all aircraft have.
Original NASA ASRS Text
Title: ATX X DSCNT THROUGH OCCUPIED ALT WHILE ON RADAR VECTOR HAD LTSS FROM ACFT Y. SYS ERROR.
Narrative: ATX X RECEIVED A CLRNC TO 4000 FT, WITH ASSIGNED HDG 220 DEGS. WHILE DSNDING THROUGH 5000 FT, MY CLRNC WAS AMENDED TO DSND AND MAINTAIN 3000 FT. I WAS THEN ASKED IF I COULD EXPEDITE MY DSCNT. SINCE 500 FPM IS NORMALLY THE MAX DSCNT RATE IN AN UNPRESSURIZED ACFT WITH PAX, I TOLD THE CTLR I WOULD BE UNABLE TO EXPEDITE THE DSCNT. I WAS THEN ASSIGNED A HDG OF 180 DEGS, AND AT THIS POINT WAS PASSING THROUGH APPROX 4300 FT. BEFORE I COULD COMPLETE THIS TURN, I WAS TOLD TO TURN FURTHER L TO A HDG OF 160 DEGS. I WAS THEN INFORMED ACFT Y AT MY 2 O'CLOCK AND 2 MI, SEBOUND, ALT 4000 FT AND WAS TOLD TO EXPEDITE MY DSCNT. SINCE I WAS ALSO APCHING 4000 FT AT THIS TIME, AND SINCE THE TURN PUT THE OTHER ACFT Y IN THE BLIND SPOT UNDER MY WING, I WAS FORCED TO INCREASE TO 1000 FPM DSCNT BRIEFLY TO AVOID THE CONFLICT. THIS SITUATION PROBABLY COULD HAVE BEEN AVOIDED HAD THE APCH CTLR HALTED MY DSCNT TEMPORARILY UNTIL I WAS CLR OF ACFT Y, GIVEN ME AN EARLIER VECTOR TO CLR THE TFC WHILE CONTINUING MY DSCNT, OR INFORMED ME OF THE TFC EARLIER, WHEN I COULD HAVE SEEN IT. I THINK PART OF THE PROBLEM IS ALSO THAT SOME CTLRS ARE NOT AWARE OF OR DO NOT UNDERSTAND PERFORMANCE LIMITATIONS OF UNPRESSURIZED ACFT AND BLIND SPOTS THAT ALL ACFT HAVE.
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.