In the event of strong fumes in the flight deck, what is the initial response?

The correct response in the event of strong fumes in the flight deck is to don an oxygen mask set to 100%. This action is critical for ensuring the safety of the flight crew. When fumes are present, there is a risk that they could be toxic or harmful to breathe, which can compromise the crew's ability to operate the aircraft effectively.

By using an oxygen mask, the crew can ensure they are receiving clean, breathable air, which protects them from potential inhalation of harmful substances. This measure is particularly important in maintaining situational awareness and cognitive function during a critical situation, allowing the crew to assess and address the source of the fumes while remaining conscious and alert.

The other options, while related to incident response, do not address the immediate respiratory protection needed when confronted with fumes. Initiating smoke evacuation procedures, activating fire suppression systems, and checking air conditioning systems may be relevant later, but the priority is to protect the crew’s health and safety first through the use of the oxygen mask.