Narrative:

On climbout; I noticed a burning smell in the cockpit. (This was our second leg in this aircraft; no problem on leg one.) I asked the lead flight attendant to turn the ovens off. The smell persisted. It smelled like plastic or rubber burning but it is hard to describe. We went to the 'smoke; fire or fumes' checklist and began turning off items in the checklist. The fumes seemed to dissipate and then return. At one point; smoke was visible to my first officer. We called dispatch to talk to [maintenance] but had a very frustrating time with the phone patch. We had some intermittent contact with [maintenance]. I switched radios to no avail and acarsed dispatch to get a new frequency. We couldn't communicate on that frequency either. Dispatch suggested that I contact [commercial radio service]. I haven't done that in about 20 years and did not have the time to find the frequency; so we communicated through ACARS. Meanwhile; I invited the lead flight attendant to the cockpit to confirm the smoke smell and she reported that it was still quite strong. There was no smell in the cabin. Since no action seemed to dissipate the fumes; we elected to divert as a precaution. Dispatch recommended [a nearby airport] and we agreed. I declared an emergency with ATC and they vectored us to the airport. I explained our problem to the passengers. I spoke with the flight attendants and did not have them prepare for evacuation. It was VFR and the first officer made a normal approach and landing (overweight at 202.8.) ATC handled the situation very well.

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Original NASA ASRS Text

Title: A B757-200 Captain reported a burning smell in the cockpit; so an emergency was declared and a divert to a nearby airport executed.

Narrative: On climbout; I noticed a burning smell in the cockpit. (This was our second leg in this aircraft; no problem on leg one.) I asked the Lead Flight Attendant to turn the ovens off. The smell persisted. It smelled like plastic or rubber burning but it is hard to describe. We went to the 'Smoke; Fire or Fumes' checklist and began turning off items in the checklist. The fumes seemed to dissipate and then return. At one point; smoke was visible to my First Officer. We called Dispatch to talk to [Maintenance] but had a very frustrating time with the phone patch. We had some intermittent contact with [Maintenance]. I switched radios to no avail and ACARSed Dispatch to get a new frequency. We couldn't communicate on that frequency either. Dispatch suggested that I contact [commercial radio service]. I haven't done that in about 20 years and did not have the time to find the frequency; so we communicated through ACARS. Meanwhile; I invited the Lead Flight Attendant to the cockpit to confirm the smoke smell and she reported that it was still quite strong. There was no smell in the cabin. Since no action seemed to dissipate the fumes; we elected to divert as a precaution. Dispatch recommended [a nearby airport] and we agreed. I declared an emergency with ATC and they vectored us to the airport. I explained our problem to the passengers. I spoke with the flight attendants and did not have them prepare for evacuation. It was VFR and the First Officer made a normal approach and landing (overweight at 202.8.) ATC handled the situation very well.

Data retrieved from NASA's ASRS site as of July 2013 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.