Crew had burning odor present in the cockpit.

Attributes
ACN	483649
Time
Date	200009
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : fsd.airport
State Reference	SD
Environment
Flight Conditions	Marginal
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zmp.artcc
Operator	common carrier : air carrier
Operating Under FAR Part	Part 121
Navigation In Use	other other vortac
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : multi engine pilot : commercial pilot : atp pilot : instrument
Experience	flight time last 90 days : 251 flight time total : 17103 flight time type : 5816
ASRS Report	483649
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : multi engine pilot : instrument
Events
Anomaly	aircraft equipment problem : critical other anomaly
Independent Detector	other flight crewa other flight crewb other other : 3
Resolutory Action	controller : provided flight assist flight crew : landed in emergency condition flight crew : diverted to another airport
Consequence	other other
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

During cruise flight at approximately XA00Z, the first officer remarked with some concern that he smelled a strong burning odor and asked if I detected any such odor. I stated after 10-15 seconds that I did as well. A flight attendant in the cockpit verified her awareness as the odor increased. I dispatched the flight attendant to assess galley/cabin conditions while the first officer and I assessed cockpit/system performance. No visible smoke was present, however, odor increased to the point that both pilots donned masks/goggles as quick reference checklists were accomplished. As both pilots were unable to locate source, a precautionary landing was elected at fsd. A 'cabin alert' was declared. No emergency was declared and crash fire rescue equipment equipment was requested. A normal approach and landing were made and passenger remained calm. A thorough troubleshooting by maintenance revealed a partially (50%) blocked first officer FMC/CDU inlet cooling filter. Mechanic stated this 'could easily have caused an overheat with the accompanying odor. Callback conversation with reporter revealed the following information: crew was flying a B757-200. Reporter submitted a company report suggesting that filter maintenance schedule be increased. He has heard nothing from the company.

Original NASA ASRS Text

Title: CREW HAD BURNING ODOR PRESENT IN THE COCKPIT.

Narrative: DURING CRUISE FLT AT APPROX XA00Z, THE FO REMARKED WITH SOME CONCERN THAT HE SMELLED A STRONG BURNING ODOR AND ASKED IF I DETECTED ANY SUCH ODOR. I STATED AFTER 10-15 SECONDS THAT I DID AS WELL. A FLT ATTENDANT IN THE COCKPIT VERIFIED HER AWARENESS AS THE ODOR INCREASED. I DISPATCHED THE FLT ATTENDANT TO ASSESS GALLEY/CABIN CONDITIONS WHILE THE FO AND I ASSESSED COCKPIT/SYS PERFORMANCE. NO VISIBLE SMOKE WAS PRESENT, HOWEVER, ODOR INCREASED TO THE POINT THAT BOTH PLTS DONNED MASKS/GOGGLES AS QUICK REF CHKLISTS WERE ACCOMPLISHED. AS BOTH PLTS WERE UNABLE TO LOCATE SOURCE, A PRECAUTIONARY LNDG WAS ELECTED AT FSD. A 'CABIN ALERT' WAS DECLARED. NO EMER WAS DECLARED AND CFR EQUIP WAS REQUESTED. A NORMAL APCH AND LNDG WERE MADE AND PAX REMAINED CALM. A THOROUGH TROUBLESHOOTING BY MAINT REVEALED A PARTIALLY (50%) BLOCKED FO FMC/CDU INLET COOLING FILTER. MECH STATED THIS 'COULD EASILY HAVE CAUSED AN OVERHEAT WITH THE ACCOMPANYING ODOR. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: CREW WAS FLYING A B757-200. RPTR SUBMITTED A COMPANY RPT SUGGESTING THAT FILTER MAINT SCHEDULE BE INCREASED. HE HAS HEARD NOTHING FROM THE COMPANY.

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.