Air carrier has master warning light activate. Smoke in cockpit, declare emergency, divert.

Attributes
ACN	225956
Time
Date	199211
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : dkk
State Reference	NY
Altitude	msl bound lower : 28000 msl bound upper : 28000
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zob
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : instrument pilot : flight engineer pilot : commercial
Experience	flight time last 90 days : 180 flight time total : 11440 flight time type : 905
ASRS Report	225956
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : declared emergency other
Consequence	Other Other
Supplementary
Primary Problem	Aircraft

Narrative:

After leveling at FL280, 'master warning' and tail comp temperature high' lights came on. We accomplished initial action items and referred to our pilot operating manual for the follow-up checklist. While following procedures to isolate a pneumatic leak, we were unable to maintain cabin altitude. Cabin altitude began climbing. ZOB was unable to give us an immediate descent, so I declared an emergency, and said we were deviating to cleveland. Center issued descent clearance when emergency was declared. At this time smoke appeared in cockpit. Communication with flight attendants confirmed that it was limited to the cockpit and it soon dissipated with cabin depressurization and throttles at idle. While accomplishing checklists, we bumped #1 navigation frequency selector off the center frequency. Communications were reestablished at cleveland approach. A smooth overweight landing (3900 pounds) was made at cle. A broken clamp was found in the tail pneumatic ducting.

Original NASA ASRS Text

Title: ACR HAS MASTER WARNING LIGHT ACTIVATE. SMOKE IN COCKPIT, DECLARE EMER, DIVERT.

Narrative: AFTER LEVELING AT FL280, 'MASTER WARNING' AND TAIL COMP TEMP HIGH' LIGHTS CAME ON. WE ACCOMPLISHED INITIAL ACTION ITEMS AND REFERRED TO OUR PLT OPERATING MANUAL FOR THE FOLLOW-UP CHKLIST. WHILE FOLLOWING PROCS TO ISOLATE A PNEUMATIC LEAK, WE WERE UNABLE TO MAINTAIN CABIN ALT. CABIN ALT BEGAN CLBING. ZOB WAS UNABLE TO GIVE US AN IMMEDIATE DSCNT, SO I DECLARED AN EMER, AND SAID WE WERE DEVIATING TO CLEVELAND. CTR ISSUED DSCNT CLRNC WHEN EMER WAS DECLARED. AT THIS TIME SMOKE APPEARED IN COCKPIT. COM WITH FLT ATTENDANTS CONFIRMED THAT IT WAS LIMITED TO THE COCKPIT AND IT SOON DISSIPATED WITH CABIN DEPRESSURIZATION AND THROTTLES AT IDLE. WHILE ACCOMPLISHING CHKLISTS, WE BUMPED #1 NAV FREQ SELECTOR OFF THE CTR FREQ. COMS WERE REESTABLISHED AT CLEVELAND APCH. A SMOOTH OVERWT LNDG (3900 POUNDS) WAS MADE AT CLE. A BROKEN CLAMP WAS FOUND IN THE TAIL PNEUMATIC DUCTING.

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.