At an incident a casualty is not breathing. To start the process to restore normal breathing you should

Explanation: It's important to ensure that the airways are clear before you start mouth to mouth resuscitation. Gently tilt their head back and use your finger to check for and remove any obvious obstruction in the mouth.

Category: Incidents, Accidents and Emergencies

References: The Official DVSA Guide to Driving: Section 16, Highway Code: Page 132