What is the first step in operating the ELT A/B?

The correct first step in operating the ELT (Emergency Locator Transmitter) A/B is to unplug the ELT from its stowage. This action is essential because it allows the device to be removed from its securing mechanism, enabling the operator to have access to it for activation.

When handling emergency equipment like the ELT, it's crucial to ensure that it is properly disconnected from any stowing device before any other actions are taken. Unplugging it frees the device so it can be effectively utilized in an emergency situation.

The other options involve actions that cannot be executed until the ELT is no longer secured in its stowage. For instance, switching the ELT to "OFF" or removing the aerial cannot be performed until the ELT is unplugged. Plugging the ELT back into its stowage is a last-resort step that isn't beneficial in an emergency scenario and doesn't align with the immediate command to activate the device.