In a no time available emergency, what command should you shout to passengers?

In a no time available emergency, the appropriate command to shout to passengers is "Brace for impact." This command serves a critical function of preparing passengers for an imminent event, such as a crash landing. By instructing them to brace for impact, you help ensure they adopt a position that can potentially minimize injury during the event.

The other options, while they may contain commands that are relevant in certain scenarios, do not effectively communicate the urgency and specific action required for a no time available emergency. For instance, "Head down, grab ankles, stay down" and "Head down, eyes forward" are more suitable for different situations where passengers have time to assume a protective position, which is not the case when time is critical. "Stay seated, remain calm" lacks the urgency and specific instructions necessary to reduce the risk of injury in such an emergency. Thus, "Brace for impact" is the clear and appropriate command that conveys the necessary actions to take in a critical situation.