<< >> NASA ASRS Report 439325, June 1999

B767 near panama city reacts to conflict and stuck microphone with late clearance to descend to avoid.

Attributes
ACN	439325
Time
Date	199906
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : mpzl.artcc
State Reference	FO
Altitude	msl bound lower : 26000 msl bound upper : 28000
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : mpzl.artcc
Operator	common carrier : air carrier
Make Model Name	B767 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	cruise : level
Route In Use	enroute other
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : mpzl.artcc
Make Model Name	Commercial Fixed Wing
Flight Phase	cruise : level
Route In Use	enroute other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	439325
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : multi engine pilot : instrument
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne critical non adherence : published procedure
Independent Detector	atc equipment : conflict alert aircraft equipment : tcas other controllera other flight crewa
Resolutory Action	flight crew : took evasive action
Supplementary
Problem Areas	Flight Crew Human Performance Environmental Factor ATC Human Performance
Primary Problem	Ambiguous

Narrative:

ATC facility: ZMA. Location: due south of panama city over gulf cruising at 280 degrees assigned. A stuck microphone from another aircraft had blocked the center frequency for several mins. I noticed an aircraft approaching head-on on TCASII at our altitude. First officer was trying to contact ATC on backup frequency. When he finally got through, we were issued an order to descend expeditiously to FL260. Cpa of oncoming aircraft was 5 mi. I disconnected the autoplt/autothrottles and pushed the nose through. Also executed 70 degree turn to left to ensure separation from head-on aircraft. No TCASII alert ever annunciated. Leveled off at FL260 and returned to heading. Rest of flight uneventful. Highlights need for additional awareness during periods of stuck microphone or other ATC communication interruptions. ATC was also well behind the developing conflict.

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Original NASA ASRS Text

Title: B767 NEAR PANAMA CITY REACTS TO CONFLICT AND STUCK MIKE WITH LATE CLRNC TO DSND TO AVOID.

Narrative: ATC FACILITY: ZMA. LOCATION: DUE S OF PANAMA CITY OVER GULF CRUISING AT 280 DEGS ASSIGNED. A STUCK MIKE FROM ANOTHER ACFT HAD BLOCKED THE CTR FREQ FOR SEVERAL MINS. I NOTICED AN ACFT APCHING HEAD-ON ON TCASII AT OUR ALT. FO WAS TRYING TO CONTACT ATC ON BACKUP FREQ. WHEN HE FINALLY GOT THROUGH, WE WERE ISSUED AN ORDER TO DSND EXPEDITIOUSLY TO FL260. CPA OF ONCOMING ACFT WAS 5 MI. I DISCONNECTED THE AUTOPLT/AUTOTHROTTLES AND PUSHED THE NOSE THROUGH. ALSO EXECUTED 70 DEG TURN TO L TO ENSURE SEPARATION FROM HEAD-ON ACFT. NO TCASII ALERT EVER ANNUNCIATED. LEVELED OFF AT FL260 AND RETURNED TO HDG. REST OF FLT UNEVENTFUL. HIGHLIGHTS NEED FOR ADDITIONAL AWARENESS DURING PERIODS OF STUCK MIKE OR OTHER ATC COM INTERRUPTIONS. ATC WAS ALSO WELL BEHIND THE DEVELOPING CONFLICT.

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.