Narrative:

At cruise altitude; we received a cargo smoke/fire indication on the EICAS with the triple stroke chime and smoke indication on the overhead panel. I was the pilot not flying (pilot in command) on this leg and began to execute memory items as the light and horn went off. At that point we reassessed the need for the extinguisher as the flight attendant had called for another reason. We asked him to go back to the lavatory and check for fire in the sight glass and smell if he could sense any signs of fire from the cargo area. He went back and reported that there was nothing in sight and was able to see well into the cargo area once the light switch was on. We went to the aom for further guidance as we had both been through ground school and told that the red annunciator without a chime and EICAS was a sign of a failed fan -- not a fire. We checked with the flight attendant again. He rechecked; no visual indication of fire; no smoke in the cargo area or the cabin; and no visual sign of any issue in the cockpit other than the light for baggage smoke. We declared an emergency; attempted for 2 minutes to contact dispatch through ACARS to no avail. I reassessed the situation and distances to several airports in the area of our flight. ZZZ was 125 miles directly in front of us and had the best combination of familiarity for us as a crew; profile for a safe descent profile and weather that was reasonable. I advised ATC of our intentions and received vectors for ZZZ. Approximately 75 miles out; ACARS kicked back a slurry of messages from dispatch and we coordinated the arrival into ZZZ. Flight attendant was briefed on the possibility of an emergency evacuation if there was a fire. Once on the ground and clear of the active runway; I requested crash fire rescue equipment check the cargo bay before any movement was started. There was no issue; taxied to gate without incident.

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Original NASA ASRS Text

Title: EMB140 flight crew declared an emergency and diverted due to what was later determined to have been a false EICAS warning of cargo smoke/fire.

Narrative: At cruise altitude; we received a Cargo Smoke/Fire indication on the EICAS with the triple stroke chime and smoke indication on the overhead panel. I was the pilot not flying (Pilot in Command) on this leg and began to execute memory items as the light and horn went off. At that point we reassessed the need for the extinguisher as the Flight Attendant had called for another reason. We asked him to go back to the lavatory and check for fire in the sight glass and smell if he could sense any signs of fire from the cargo area. He went back and reported that there was nothing in sight and was able to see well into the cargo area once the light switch was on. We went to the AOM for further guidance as we had both been through ground school and told that the red annunciator without a chime and EICAS was a sign of a failed fan -- not a fire. We checked with the Flight Attendant again. He rechecked; no visual indication of fire; no smoke in the cargo area or the cabin; and no visual sign of any issue in the cockpit other than the light for baggage smoke. We declared an emergency; attempted for 2 minutes to contact dispatch through ACARS to no avail. I reassessed the situation and distances to several airports in the area of our flight. ZZZ was 125 miles directly in front of us and had the best combination of familiarity for us as a crew; profile for a safe descent profile and weather that was reasonable. I advised ATC of our intentions and received vectors for ZZZ. Approximately 75 miles out; ACARS kicked back a slurry of messages from dispatch and we coordinated the arrival into ZZZ. Flight Attendant was briefed on the possibility of an emergency evacuation if there was a fire. Once on the ground and clear of the active runway; I requested CFR check the cargo bay before any movement was started. There was no issue; taxied to gate without incident.

Data retrieved from NASA's ASRS site as of April 2012 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.