 |
37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
|
Flight crew of medium large transport at 4000 had TCASII RA (descend) flight had been cleared to 3000. Flight crew expedited descent, cleared RA.
| Attributes | |
| ACN | 195024 |
| Time | |
| Date | 199111 |
| Day | Sat |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : dfw |
| State Reference | TX |
| Altitude | msl bound lower : 3000 msl bound upper : 4000 |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : dfw |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport, Low Wing, 2 Turbojet Eng |
| Navigation In Use | Other Other |
| Flight Phase | descent : approach descent other |
| Route In Use | arrival other enroute : on vectors |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp pilot : cfi pilot : commercial pilot : flight engineer pilot : instrument |
| Experience | flight time last 90 days : 150 flight time total : 11300 flight time type : 700 |
| ASRS Report | 195024 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp pilot : commercial pilot : instrument |
| Events | |
| Anomaly | other anomaly other |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other flight crewa |
| Resolutory Action | flight crew : took evasive action |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | other |
Narrative:
We had accomplished the blue ridge arrival and now on radar vectors for the ILS 17L (1) at dfw. Our speed was 180 KTS assigned and altitude 4000 ft, our heading was 240 degree. ATC approach control then had a shift change because the voice had changed. We were then told to turn left to a heading of 170 degree and intercept the ILS 17L localizer and that we would 'overfly the centerline and may observe traffic on the approach to 18R at 3000 ft who would also be overflying the localizer east of course under us.' at this point in time we were almost solid IFR, however, we did have visual contact with the other aircraft intermittently. The next clearance from ATC advised us that we were to slow to 170 KTS and then descend to 3000 ft and cleared for the ILS runway 17L. After slowing to 170 KTS and just beginning to descend TCASII issued us a RA to 'descend, descend now' and the vsi showed a descend command of about 1000 FPM rate to clear the conflict. We intermittently saw the conflicting traffic, it was a commuter aircraft on the downwind leg for the same ILS that we were on. The aircraft appeared to be an mdt. We were established on the centerline of the ILS 17L when this occurred, we also concurred with each other in the cockpit that we were in fact on the right ILS and that we were doing as per the ATC instructions. The traffic was not a real threat to our approach and we did not alter our course except that I did expedite our descent to 3000 ft and TCASII issued a 'clear of conflict' almost immediately after we started to descend. Apparently ATC approach control was very busy with traffic and a shift change and allowed things to get out of hand, also the WX was a factor. We did not have to violate or descend to avoid this traffic and because we were already cleared to 3000 ft anyway we did not deviation from approach's instructions. It was a surprise to get a RA in IFR conditions and to see other traffic in close proximity while on an ILS approach.
Original NASA ASRS Text
Title: FLC OF MLG AT 4000 HAD TCASII RA (DSND) FLT HAD BEEN CLRED TO 3000. FLC EXPEDITED DSCNT, CLRED RA.
Narrative: WE HAD ACCOMPLISHED THE BLUE RIDGE ARR AND NOW ON RADAR VECTORS FOR THE ILS 17L (1) AT DFW. OUR SPD WAS 180 KTS ASSIGNED AND ALT 4000 FT, OUR HDG WAS 240 DEG. ATC APCH CTL THEN HAD A SHIFT CHANGE BECAUSE THE VOICE HAD CHANGED. WE WERE THEN TOLD TO TURN L TO A HDG OF 170 DEG AND INTERCEPT THE ILS 17L LOC AND THAT WE WOULD 'OVERFLY THE CENTERLINE AND MAY OBSERVE TFC ON THE APCH TO 18R AT 3000 FT WHO WOULD ALSO BE OVERFLYING THE LOC E OF COURSE UNDER US.' AT THIS POINT IN TIME WE WERE ALMOST SOLID IFR, HOWEVER, WE DID HAVE VISUAL CONTACT WITH THE OTHER ACFT INTERMITTENTLY. THE NEXT CLRNC FROM ATC ADVISED US THAT WE WERE TO SLOW TO 170 KTS AND THEN DSND TO 3000 FT AND CLRED FOR THE ILS RWY 17L. AFTER SLOWING TO 170 KTS AND JUST BEGINNING TO DSND TCASII ISSUED US A RA TO 'DSND, DSND NOW' AND THE VSI SHOWED A DSND COMMAND OF ABOUT 1000 FPM RATE TO CLR THE CONFLICT. WE INTERMITTENTLY SAW THE CONFLICTING TFC, IT WAS A COMMUTER ACFT ON THE DOWNWIND LEG FOR THE SAME ILS THAT WE WERE ON. THE ACFT APPEARED TO BE AN MDT. WE WERE ESTABLISHED ON THE CENTERLINE OF THE ILS 17L WHEN THIS OCCURRED, WE ALSO CONCURRED WITH EACH OTHER IN THE COCKPIT THAT WE WERE IN FACT ON THE RIGHT ILS AND THAT WE WERE DOING AS PER THE ATC INSTRUCTIONS. THE TFC WAS NOT A REAL THREAT TO OUR APCH AND WE DID NOT ALTER OUR COURSE EXCEPT THAT I DID EXPEDITE OUR DSCNT TO 3000 FT AND TCASII ISSUED A 'CLR OF CONFLICT' ALMOST IMMEDIATELY AFTER WE STARTED TO DSND. APPARENTLY ATC APCH CTL WAS VERY BUSY WITH TFC AND A SHIFT CHANGE AND ALLOWED THINGS TO GET OUT OF HAND, ALSO THE WX WAS A FACTOR. WE DID NOT HAVE TO VIOLATE OR DSND TO AVOID THIS TFC AND BECAUSE WE WERE ALREADY CLRED TO 3000 FT ANYWAY WE DID NOT DEV FROM APCH'S INSTRUCTIONS. IT WAS A SURPRISE TO GET A RA IN IFR CONDITIONS AND TO SEE OTHER TFC IN CLOSE PROX WHILE ON AN ILS APCH.
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.