Less than standard separation when small transport took descent clearance meant for another aircraft and came into conflict with an light transport, opposite direction on the same airway.

Home

Browse by month

Random

Latest

About

Contact

Attributes
ACN	92620
Time
Date	198808
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : sey
State Reference	RI
Altitude	msl bound lower : 12000 msl bound upper : 12500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zbw tower : bos
Operator	general aviation : corporate
Make Model Name	Small Transport, Low Wing, 2 Recip Eng
Flight Phase	cruise other descent other
Route In Use	enroute airway : v268
Flight Plan	IFR
Aircraft 2
Operator	other
Make Model Name	Military Transport
Flight Phase	cruise other descent other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller non radar : 3 controller radar : 3
ASRS Report	92620
Person 2
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne less severe conflict : ground less severe
Independent Detector	atc equipment other atc equipment : unspecified other controllera
Resolutory Action	controller : issued new clearance flight crew : returned to intended course or assigned course none taken : insufficient time
Consequence	faa : investigated
Miss Distance	horizontal : 10500 vertical : 500
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Pilot Deviation Operational Error

Narrative:

Small transport X took clearance meant for mlt Y and descended through light transport Z below him. Callback conversation with reporter revealed the following: small transport X and mlt Y were both northeast bound V268, with small transport X landing ewb and mlt Y landing nzw. Light transport Z was opposite direction at 12000'. Both small transport X and mlt Y were at 13000'. Reporter gave descent clearance to mlt Y and both mlt Y and small transport X acknowledged for the clearance. Reporter did not hear small transport X acknowledge. Later, during the investigation, and while listening to the tapes, it was found that mlt Y's acknowledgement was only a hiss and the readback from small transport X is loud and clear. Reporter admitted that he did not hear the wrong aircraft answer for the descent clearance. By the time he saw the mode C of small transport X showing descent, it was too late to correct the mistake and avoid a loss of sep.

Original NASA ASRS Text

Title: LESS THAN STANDARD SEPARATION WHEN SMT TOOK DESCENT CLRNC MEANT FOR ANOTHER ACFT AND CAME INTO CONFLICT WITH AN LTT, OPPOSITE DIRECTION ON THE SAME AIRWAY.

Narrative: SMT X TOOK CLRNC MEANT FOR MLT Y AND DSNDED THROUGH LTT Z BELOW HIM. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: SMT X AND MLT Y WERE BOTH NE BOUND V268, WITH SMT X LNDG EWB AND MLT Y LNDG NZW. LTT Z WAS OPPOSITE DIRECTION AT 12000'. BOTH SMT X AND MLT Y WERE AT 13000'. RPTR GAVE DSCNT CLRNC TO MLT Y AND BOTH MLT Y AND SMT X ACKNOWLEDGED FOR THE CLRNC. RPTR DID NOT HEAR SMT X ACKNOWLEDGE. LATER, DURING THE INVESTIGATION, AND WHILE LISTENING TO THE TAPES, IT WAS FOUND THAT MLT Y'S ACKNOWLEDGEMENT WAS ONLY A HISS AND THE READBACK FROM SMT X IS LOUD AND CLEAR. RPTR ADMITTED THAT HE DID NOT HEAR THE WRONG ACFT ANSWER FOR THE DSCNT CLRNC. BY THE TIME HE SAW THE MODE C OF SMT X SHOWING DSCNT, IT WAS TOO LATE TO CORRECT THE MISTAKE AND AVOID A LOSS OF SEP.

Data retrieved from NASA's ASRS site as of August 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.