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Aircraft descended below assigned altitude resulting in less than standard separation with another aircraft.
| Attributes | |
| ACN | 113380 |
| Time | |
| Date | 198905 |
| Day | Wed |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : shv |
| State Reference | LA |
| Altitude | msl bound lower : 3000 msl bound upper : 3600 |
| Environment | |
| Flight Conditions | Mixed |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : shv |
| Operator | general aviation : personal |
| Make Model Name | Small Transport, Low Wing, 2 Turboprop Eng |
| Flight Phase | descent : approach descent other |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | general aviation : corporate |
| Make Model Name | Small Transport, Low Wing, 2 Recip Eng |
| Flight Phase | cruise other descent : approach |
| Route In Use | arrival other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : approach |
| Qualification | controller : radar |
| Experience | controller military : 3 controller radar : 1 |
| ASRS Report | 113380 |
| Person 2 | |
| Affiliation | Other |
| Function | flight crew : single pilot |
| Qualification | pilot : instrument pilot : cfi |
| Events | |
| Anomaly | conflict : airborne less severe non adherence : required legal separation non adherence : published procedure other anomaly other |
| Independent Detector | other controllera |
| Resolutory Action | controller : issued new clearance |
| Consequence | Other |
| Miss Distance | horizontal : 12000 vertical : 600 |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error |
Narrative:
Aircraft #1 was IFR making multiple apches. Pilot requested an NDB runway 14 approach on own navigation, aircraft #1 was assigned 3000'. Aircraft #2, IFR inbound from the northeast was being vectored at 3000' for an ILS runway 14 approach. Realizing a possible confliction, aircraft #1 was then assigned 4000' and was told it was because of traffic. As aircraft #1 approached crakk NDB, he asked if cleared for approach. Aircraft #1 was issued, cross the NDB at 4000 maintain 4000 until advised cleared for NDB runway 14 approach. Aircraft #1 read back, 4000 'till established cleared NDB runway 14. Controller did not catch the word 'established' and thought the readback was good. After making a verbal handoff on a landline, the controller saw a mode C readout of 3700' from aircraft #1 and immediately reemphasized to maintain 4000 and told him of aircraft #2 which was straight ahead at 3000'. Aircraft #1's reply indicated he did not know he was supposed to be at 4000'. The controller quickly reassigned 4000' and aircraft #1 climbed quickly to 4000' and the controller explained that he wanted aircraft #1 to remain at 4000' until advised otherwise. Aircraft #2 passed underneath aircraft #1 on approach to runway 14, and since aircraft #1 was still outbnd the controller removed the altitude restriction. Aircraft #1 was transferred to tower frequency the aircraft transitioned to an ILS approach without clearance. The aircraft made 2 more apches before landing.
Original NASA ASRS Text
Title: ACFT DESCENDED BELOW ASSIGNED ALT RESULTING IN LESS THAN STANDARD SEPARATION WITH ANOTHER ACFT.
Narrative: ACFT #1 WAS IFR MAKING MULTIPLE APCHES. PLT REQUESTED AN NDB RWY 14 APCH ON OWN NAVIGATION, ACFT #1 WAS ASSIGNED 3000'. ACFT #2, IFR INBND FROM THE NE WAS BEING VECTORED AT 3000' FOR AN ILS RWY 14 APCH. REALIZING A POSSIBLE CONFLICTION, ACFT #1 WAS THEN ASSIGNED 4000' AND WAS TOLD IT WAS BECAUSE OF TFC. AS ACFT #1 APCHED CRAKK NDB, HE ASKED IF CLRED FOR APCH. ACFT #1 WAS ISSUED, CROSS THE NDB AT 4000 MAINTAIN 4000 UNTIL ADVISED CLRED FOR NDB RWY 14 APCH. ACFT #1 READ BACK, 4000 'TILL ESTABLISHED CLRED NDB RWY 14. CTLR DID NOT CATCH THE WORD 'ESTABLISHED' AND THOUGHT THE READBACK WAS GOOD. AFTER MAKING A VERBAL HANDOFF ON A LANDLINE, THE CTLR SAW A MODE C READOUT OF 3700' FROM ACFT #1 AND IMMEDIATELY REEMPHASIZED TO MAINTAIN 4000 AND TOLD HIM OF ACFT #2 WHICH WAS STRAIGHT AHEAD AT 3000'. ACFT #1'S REPLY INDICATED HE DID NOT KNOW HE WAS SUPPOSED TO BE AT 4000'. THE CTLR QUICKLY REASSIGNED 4000' AND ACFT #1 CLIMBED QUICKLY TO 4000' AND THE CTLR EXPLAINED THAT HE WANTED ACFT #1 TO REMAIN AT 4000' UNTIL ADVISED OTHERWISE. ACFT #2 PASSED UNDERNEATH ACFT #1 ON APCH TO RWY 14, AND SINCE ACFT #1 WAS STILL OUTBND THE CTLR REMOVED THE ALT RESTRICTION. ACFT #1 WAS TRANSFERRED TO TWR FREQ THE ACFT TRANSITIONED TO AN ILS APCH WITHOUT CLRNC. THE ACFT MADE 2 MORE APCHES BEFORE LNDG.
Data retrieved from NASA's ASRS site as of August 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.