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An air carrier DC9 flight crew descended below their assigned altitude when the captain became distraction by an expected crossing altitude assignment and the TCASII warning of a lower altitude C130.
| Attributes | |
| ACN | 426580 |
| Time | |
| Date | 199901 |
| Day | Sun |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : ujm |
| State Reference | AR |
| Altitude | msl bound lower : 18500 msl bound upper : 19000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Flight Phase | descent other |
| Route In Use | arrival other arrival star : star |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | other |
| Flight Phase | cruise other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : commercial pilot : flight engineer pilot : instrument |
| Experience | flight time last 90 days : 200 flight time total : 18000 flight time type : 900 |
| ASRS Report | 426580 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : commercial |
| Events | |
| Anomaly | altitude deviation : overshoot conflict : airborne less severe non adherence : far |
| Independent Detector | other flight crewa |
| Consequence | Other |
| Miss Distance | horizontal : 24000 vertical : 500 |
| Supplementary | |
| Air Traffic Incident | Pilot Deviation |
Narrative:
At FL330, ATC cleared us to descend to FL190 expect tammy intersection at 10000 ft. During descent, I thought ATC reclred us down to 10000 ft. During the descent, I was high and fast and became concerned about making the crossing restr at tammy. Preoccupied with the calculation, I forgot that FL190 was the altitude that I was cleared to. The first officer called my attention to the altitude at FL187 and it took 200 ft to stop the aircraft at FL185. I promptly returned aircraft to FL190. About FL200 the TCASII indicated traffic off the scope to the right. At FL195, TCASII commanded a reduced rate of descent. Part of my attention was diverted to looking for the aircraft and slowing the descent and not checking the altitude that was set in the altitude alert window (FL190). The altitude alert worked normally, although it was not noticed because of the TCASII alert.
Original NASA ASRS Text
Title: AN ACR DC9 FLC DSNDED BELOW THEIR ASSIGNED ALT WHEN THE CAPT BECAME DISTR BY AN EXPECTED XING ALT ASSIGNMENT AND THE TCASII WARNING OF A LOWER ALT C130.
Narrative: AT FL330, ATC CLRED US TO DSND TO FL190 EXPECT TAMMY INTXN AT 10000 FT. DURING DSCNT, I THOUGHT ATC RECLRED US DOWN TO 10000 FT. DURING THE DSCNT, I WAS HIGH AND FAST AND BECAME CONCERNED ABOUT MAKING THE XING RESTR AT TAMMY. PREOCCUPIED WITH THE CALCULATION, I FORGOT THAT FL190 WAS THE ALT THAT I WAS CLRED TO. THE FO CALLED MY ATTN TO THE ALT AT FL187 AND IT TOOK 200 FT TO STOP THE ACFT AT FL185. I PROMPTLY RETURNED ACFT TO FL190. ABOUT FL200 THE TCASII INDICATED TFC OFF THE SCOPE TO THE R. AT FL195, TCASII COMMANDED A REDUCED RATE OF DSCNT. PART OF MY ATTN WAS DIVERTED TO LOOKING FOR THE ACFT AND SLOWING THE DSCNT AND NOT CHKING THE ALT THAT WAS SET IN THE ALT ALERT WINDOW (FL190). THE ALT ALERT WORKED NORMALLY, ALTHOUGH IT WAS NOT NOTICED BECAUSE OF THE TCASII ALERT.
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.