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TCASII RA forces flight crew and ATC to amend the clearance altitude as flight was descending through to occupied altitude.
| Attributes | |
| ACN | 266931 |
| Time | |
| Date | 199403 |
| Day | Tue |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : dca |
| State Reference | DC |
| Altitude | msl bound lower : 4700 msl bound upper : 5000 |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : dca |
| Operator | common carrier : air carrier |
| Make Model Name | B737-400 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other Other |
| Flight Phase | descent other |
| Flight Plan | IFR |
| Aircraft 2 | |
| Make Model Name | Commercial Fixed Wing |
| Operating Under FAR Part | other : unknown |
| Flight Phase | cruise other |
| Route In Use | enroute : on vectors |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp pilot : flight engineer |
| Experience | flight time last 90 days : 180 flight time total : 10100 flight time type : 1400 |
| ASRS Report | 266931 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Events | |
| Anomaly | conflict : airborne less severe non adherence : published procedure non adherence : required legal separation non adherence : far other anomaly other |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified |
| Resolutory Action | controller : issued new clearance flight crew : exited adverse environment flight crew : took evasive action |
| Consequence | Other |
| Miss Distance | horizontal : 15000 vertical : 700 |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error |
Narrative:
Flight inbound to dca from cmh. On descent between aml and dca, about ready for turn downwind for ILS runway 37 at dca. Descending through 5000 ft for clearance altitude of 2500 ft got TA on TCASII for target at 11 O'clock less than 1000 ft below and believe less than 3 mi. (Estimate at about 2 1/2 mi.) then got RA to 'stop descent.' took manual control and leveled off at about 4700 ft. First officer notified approach control who told us to maintain 5000 ft. Ascended to 5000 ft, leveled off and reengaged autoplt. We were overtaking target and were at a speed of about 240 KTS. TCASII probably saved a very close call. Dca approach should have been able to see potential conflict. Conditions were hard IMC in light rain.
Original NASA ASRS Text
Title: TCASII RA FORCES FLC AND ATC TO AMEND THE CLRNC ALT AS FLT WAS DSNDING THROUGH TO OCCUPIED ALT.
Narrative: FLT INBOUND TO DCA FROM CMH. ON DSCNT BTWN AML AND DCA, ABOUT READY FOR TURN DOWNWIND FOR ILS RWY 37 AT DCA. DSNDING THROUGH 5000 FT FOR CLRNC ALT OF 2500 FT GOT TA ON TCASII FOR TARGET AT 11 O'CLOCK LESS THAN 1000 FT BELOW AND BELIEVE LESS THAN 3 MI. (ESTIMATE AT ABOUT 2 1/2 MI.) THEN GOT RA TO 'STOP DSCNT.' TOOK MANUAL CTL AND LEVELED OFF AT ABOUT 4700 FT. FO NOTIFIED APCH CTL WHO TOLD US TO MAINTAIN 5000 FT. ASCENDED TO 5000 FT, LEVELED OFF AND REENGAGED AUTOPLT. WE WERE OVERTAKING TARGET AND WERE AT A SPD OF ABOUT 240 KTS. TCASII PROBABLY SAVED A VERY CLOSE CALL. DCA APCH SHOULD HAVE BEEN ABLE TO SEE POTENTIAL CONFLICT. CONDITIONS WERE HARD IMC IN LIGHT RAIN.
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.