Narrative:

We took off and experienced a severe vibration on the number one engine (6.0+). We declared an emergency with ATC and were being vectored back while executing the appropriate checklist. The flight attendants were briefed using the test acronym and the cabin was prepped for an evacuation.

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Original NASA ASRS Text

Title: Air Carrier Captain experiences severe vibration in the left engine shortly after takeoff and declares an emergency. Flight is vectored back for landing at the departure airport.

Narrative: We took off and experienced a severe vibration on the number one engine (6.0+). We declared an emergency with ATC and were being vectored back while executing the appropriate checklist. The flight attendants were briefed using the TEST acronym and the cabin was prepped for an evacuation.

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.