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Air carrier medium large transport cleared to descend to FL310 but misunderstood clearance and descended to FL300. First officer was alone in cockpit at the time and may have been distracted when told to expedite descent.
| Attributes | |
| ACN | 366790 |
| Time | |
| Date | 199704 |
| Day | Tue |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : mkg |
| State Reference | MI |
| Altitude | msl bound lower : 30000 msl bound upper : 31000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zob |
| Operator | common carrier : air carrier |
| Make Model Name | Commercial Fixed Wing |
| Operating Under FAR Part | Part 121 |
| Flight Phase | descent other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 75 flight time total : 6950 flight time type : 40 |
| ASRS Report | 366790 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | altitude deviation : overshoot non adherence : clearance |
| Independent Detector | other controllera |
| Resolutory Action | controller : issued new clearance |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
I was in cruise flight at FL350. The captain had stepped in the back for personal reasons for a moment. ZOB asked for a descent to FL300 and a right turn of 40 degrees -- my heading was 270 degrees initially. They also requested, ATC that I expedite the descent through FL330. I read back this clearance, set FL330 in the altitude alerter and initiated a descent. After leveling at FL300 the controller asked if I would climb to FL310. I asked him to then verify that FL300 was assigned. He then said that's okay continue descent to FL280. The captain then returned from the back and I explained the exchange to him. There was obviously some miscoms taking place. Corrective measures: higher state of vigilance when one crew member is out of the cockpit. Strict adherence to altitude alerter procedures. Positive feedback to assigned altitude. Minimizing the use of multiple requirements for altitude, heading, airspeed and rates of descent for the use of separation in the high altitude airspace.
Original NASA ASRS Text
Title: ACR MLG CLRED TO DSND TO FL310 BUT MISUNDERSTOOD CLRNC AND DSNDED TO FL300. FO WAS ALONE IN COCKPIT AT THE TIME AND MAY HAVE BEEN DISTRACTED WHEN TOLD TO EXPEDITE DSCNT.
Narrative: I WAS IN CRUISE FLT AT FL350. THE CAPT HAD STEPPED IN THE BACK FOR PERSONAL REASONS FOR A MOMENT. ZOB ASKED FOR A DSCNT TO FL300 AND A R TURN OF 40 DEGS -- MY HDG WAS 270 DEGS INITIALLY. THEY ALSO REQUESTED, ATC THAT I EXPEDITE THE DSCNT THROUGH FL330. I READ BACK THIS CLRNC, SET FL330 IN THE ALT ALERTER AND INITIATED A DSCNT. AFTER LEVELING AT FL300 THE CTLR ASKED IF I WOULD CLB TO FL310. I ASKED HIM TO THEN VERIFY THAT FL300 WAS ASSIGNED. HE THEN SAID THAT'S OKAY CONTINUE DSCNT TO FL280. THE CAPT THEN RETURNED FROM THE BACK AND I EXPLAINED THE EXCHANGE TO HIM. THERE WAS OBVIOUSLY SOME MISCOMS TAKING PLACE. CORRECTIVE MEASURES: HIGHER STATE OF VIGILANCE WHEN ONE CREW MEMBER IS OUT OF THE COCKPIT. STRICT ADHERENCE TO ALT ALERTER PROCS. POSITIVE FEEDBACK TO ASSIGNED ALT. MINIMIZING THE USE OF MULTIPLE REQUIREMENTS FOR ALT, HEADING, AIRSPD AND RATES OF DSCNT FOR THE USE OF SEPARATION IN THE HIGH ALT AIRSPACE.
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.