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An air carrier flight crew flying a B737-400 near rdu reports misunderstanding with an ATC clearance to maintain 250 KTS.
| Attributes | |
| ACN | 481999 |
| Time | |
| Date | 200008 |
| Day | Fri |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | navaid : rdu.ils |
| State Reference | NC |
| Altitude | msl bound lower : 23000 msl bound upper : 24000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Dusk |
| Aircraft 1 | |
| Controlling Facilities | artcc : zdc.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | B737-400 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other |
| Flight Phase | climbout : intermediate altitude |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : multi engine pilot : instrument pilot : flight engineer pilot : commercial pilot : cfi pilot : atp pilot : private |
| Experience | flight time last 90 days : 100 flight time total : 14000 flight time type : 4600 |
| ASRS Report | 481999 |
| Person 2 | |
| Affiliation | company : air carrier government : faa |
| Function | controller : radar flight crew : first officer |
| Qualification | controller : radar pilot : commercial pilot : instrument pilot : multi engine pilot : atp |
| Experience | flight time last 90 days : 150 flight time total : 4000 flight time type : 300 |
| ASRS Report | 481840 |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude non adherence : far non adherence : clearance |
| Independent Detector | other controllerb |
| Resolutory Action | controller : provided flight assist controller : issued new clearance flight crew : became reoriented |
| Supplementary | |
| Problem Areas | Flight Crew Human Performance ATC Human Performance |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
Level FL230, waiting to climb FL270. I heard and first officer heard 'maintain FL250.' first officer read back 'climb FL250.' controller replied, 'roger.' at FL240 controller said we were supposed to be at FL230. I believe controller now meant maintain 250 was for speed, not altitude. No conflicts observed. ATC should use different words for speed changes to prevent confusion for speed 250, FL250, and heading 250. Controller was busy vectoring aircraft around isolated thunderstorm cells, and slowing aircraft for phl delays, we later realized. ATC frequency 127.75 ZDC.
Original NASA ASRS Text
Title: AN ACR FLC FLYING A B737-400 NEAR RDU RPTS MISUNDERSTANDING WITH AN ATC CLRNC TO MAINTAIN 250 KTS.
Narrative: LEVEL FL230, WAITING TO CLB FL270. I HEARD AND FO HEARD 'MAINTAIN FL250.' FO READ BACK 'CLB FL250.' CTLR REPLIED, 'ROGER.' AT FL240 CTLR SAID WE WERE SUPPOSED TO BE AT FL230. I BELIEVE CTLR NOW MEANT MAINTAIN 250 WAS FOR SPD, NOT ALT. NO CONFLICTS OBSERVED. ATC SHOULD USE DIFFERENT WORDS FOR SPD CHANGES TO PREVENT CONFUSION FOR SPD 250, FL250, AND HEADING 250. CTLR WAS BUSY VECTORING ACFT AROUND ISOLATED TSTM CELLS, AND SLOWING ACFT FOR PHL DELAYS, WE LATER REALIZED. ATC FREQ 127.75 ZDC.
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.