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Air carrier large transport altitude deviation excursion from clearance altitude in response to TCASII RA. Controller reporter says the deviation was in the wrong direction but was as indicated on TCASII to the flight crew of the large transport.
| Attributes | |
| ACN | 199366 |
| Time | |
| Date | 199112 |
| Day | Wed |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : shv |
| State Reference | LA |
| Altitude | msl bound lower : 27000 msl bound upper : 27400 |
| Environment | |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zfw |
| Operator | common carrier : air carrier |
| Make Model Name | Large Transport, Low Wing, 3 Turbojet Eng |
| Flight Phase | cruise other |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | common carrier : air carrier |
| Make Model Name | Heavy Transport, Low Wing, 4 Turbojet Eng |
| Flight Phase | cruise other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : radar |
| Qualification | controller : radar |
| Experience | controller radar : 6 |
| ASRS Report | 199366 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | aircraft equipment problem : critical altitude deviation : excursion from assigned altitude conflict : airborne less severe |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other controllera |
| Resolutory Action | none taken : anomaly accepted |
| Consequence | Other |
| Miss Distance | horizontal : 13200 vertical : 600 |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | Pilot Deviation |
Narrative:
An air carrier large transport with RNAV and TCASII was proceeding sebound just south of GGG VORTAC, level at an interim altitude of FL270. A modified heavy transport was wswbound, southeast of GGG VORTAC, level at FL280. Traffic was issued to each aircraft as required by FAA 7110.65F 'merging target procedures.' neither aircraft reported seeing the other aircraft. The heavy transport aircraft passed to the left and just behind the large transport aircraft. The large transport aircraft's TCASII system generated an RA just prior to this point when the heavy transport aircraft was at large transport's 10 O'clock position. The large transport aircraft climbed 400 ft to FL274 just as the heavy transport passed abeam with less than 5 mi lateral separation. When queried about his altitude the pilot of the large transport stated he had received a TCASII RA showing the aircraft at his 10 O'clock position (corresponding to the position of heavy transport to be 500 ft below him (rather than 1000 ft above him) and commanding a climb of 400 ft to avoid conflict. The mode C reply from the heavy transport showed FL279 in all replies to the center's radar. A third aircraft, 2 fgts, were in the 2 O'clock position of the large transport at a range of approximately 7 mi, level at FL260. The pilot of the large transport aircraft stated he did not see the 2 O'clock traffic on the TCASII. This is a good example of a dangerous situation created by a system designed to improve safety. There is no justifiable reason for aircraft to be taking evasive action in the positive control area, where all traffic is known and separated, while the aircraft is in direct communication with a control facility.
Original NASA ASRS Text
Title: ACR LGT ALTDEV EXCURSION FROM CLRNC ALT IN RESPONSE TO TCASII RA. CTLR RPTR SAYS THE DEV WAS IN THE WRONG DIRECTION BUT WAS AS INDICATED ON TCASII TO THE FLC OF THE LGT.
Narrative: AN ACR LGT WITH RNAV AND TCASII WAS PROCEEDING SEBOUND JUST S OF GGG VORTAC, LEVEL AT AN INTERIM ALT OF FL270. A MODIFIED HVT WAS WSWBOUND, SE OF GGG VORTAC, LEVEL AT FL280. TFC WAS ISSUED TO EACH ACFT AS REQUIRED BY FAA 7110.65F 'MERGING TARGET PROCS.' NEITHER ACFT RPTED SEEING THE OTHER ACFT. THE HVT ACFT PASSED TO THE L AND JUST BEHIND THE LGT ACFT. THE LGT ACFT'S TCASII SYS GENERATED AN RA JUST PRIOR TO THIS POINT WHEN THE HVT ACFT WAS AT LGT'S 10 O'CLOCK POS. THE LGT ACFT CLBED 400 FT TO FL274 JUST AS THE HVT PASSED ABEAM WITH LESS THAN 5 MI LATERAL SEPARATION. WHEN QUERIED ABOUT HIS ALT THE PLT OF THE LGT STATED HE HAD RECEIVED A TCASII RA SHOWING THE ACFT AT HIS 10 O'CLOCK POS (CORRESPONDING TO THE POS OF HVT TO BE 500 FT BELOW HIM (RATHER THAN 1000 FT ABOVE HIM) AND COMMANDING A CLB OF 400 FT TO AVOID CONFLICT. THE MODE C REPLY FROM THE HVT SHOWED FL279 IN ALL REPLIES TO THE CENTER'S RADAR. A THIRD ACFT, 2 FGTS, WERE IN THE 2 O'CLOCK POS OF THE LGT AT A RANGE OF APPROX 7 MI, LEVEL AT FL260. THE PLT OF THE LGT ACFT STATED HE DID NOT SEE THE 2 O'CLOCK TFC ON THE TCASII. THIS IS A GOOD EXAMPLE OF A DANGEROUS SITUATION CREATED BY A SYS DESIGNED TO IMPROVE SAFETY. THERE IS NO JUSTIFIABLE REASON FOR ACFT TO BE TAKING EVASIVE ACTION IN THE PCA, WHERE ALL TFC IS KNOWN AND SEPARATED, WHILE THE ACFT IS IN DIRECT COM WITH A CTL FACILITY.
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.