Final answer:
In the event of duress during a convoy, a duress code or signal is used as a discreet communication check to indicate distress without tipping off the adversary.
Step-by-step explanation:
The communication check used in the event of duress during a convoy is typically a duress code or duress signal, which are pre-arranged signals or words that are integrated into normal communication to indicate that the person is under threat without alerting the perpetrators. These checks are part of security protocols to ensure the safety of personnel and the integrity of operations. When a convoy is in a duress situation, the individual under duress may use these signals in radio communication, written messages, or even through specific gestures if they are under visual surveillance, to alert their team or command center of the situation discreetly. Such procedures are essential in tactics and security operations, making it crucial for all members of the convoy to be well-versed in their designated duress codes and signals.