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Indianapolis center controller reported that he calculated incorrectly the altitudes useable relating to the altimeter being 30.65.
| Attributes | |
| ACN | 1410624 |
| Time | |
| Date | 201612 |
| Local Time Of Day | 0001-0600 |
| Place | |
| Locale Reference | ZID.ARTCC |
| State Reference | IN |
| Aircraft 1 | |
| Make Model Name | Medium Transport Low Wing 2 Turboprop Eng |
| Flight Phase | Descent |
| Flight Plan | IFR |
| Aircraft 2 | |
| Make Model Name | Commercial Fixed Wing |
| Flight Phase | Cruise |
| Flight Plan | IFR |
| Person 1 | |
| Function | Enroute |
| Qualification | Air Traffic Control Fully Certified |
| Experience | Air Traffic Control Time Certified In Pos 1 (yrs) 16 |
| Events | |
| Anomaly | ATC Issue All Types Conflict Airborne Conflict Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy |
Narrative:
Aircraft X was inbound to ind. Aircraft Y was an overflight at FL180. I gave aircraft X an expedited descent rate to get under aircraft Y; and then give a descend via clearance. I kept running vector lines out; and it looked good. What I didn't factor in was altimeter settings. 30.65 was the indy altimeter. Aircraft X was doing 2000 fpm in the descent; but there was a the changing of altimeter settings that I did not account for. So I had about 4.5 miles. 17;200 feet on 30.65; and FL180. 17;000 and FL180 were actually 1720 feet apart by my math. Conflict alert activated.beware of altimeter settings. Don't try to push aircraft through each other.
Original NASA ASRS Text
Title: Indianapolis Center Controller reported that he calculated incorrectly the altitudes useable relating to the altimeter being 30.65.
Narrative: Aircraft X was inbound to IND. Aircraft Y was an overflight at FL180. I gave Aircraft X an expedited descent rate to get under Aircraft Y; and then give a descend via clearance. I kept running vector lines out; and it looked good. What I didn't factor in was altimeter settings. 30.65 was the Indy altimeter. Aircraft X was doing 2000 fpm in the descent; but there was a the changing of altimeter settings that I did not account for. So I had about 4.5 miles. 17;200 feet on 30.65; and FL180. 17;000 and FL180 were actually 1720 feet apart by my math. Conflict alert activated.Beware of altimeter settings. Don't try to push aircraft through each other.
Data retrieved from NASA's ASRS site 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.