presence of mind

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The ability to think and act calmly and efficiently, especially in an emergency.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Focused alertness, quick-thinking resourcefulness, stability of thought and feeling, or good sense, especially in spite of circumstances which are distracting, stressful, or otherwise challenging.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun self-control in a crisis; ability to say or do the right thing in an emergency