What component warns crew about the placement of jet bridges or air stairs?

The correct answer highlights the importance of door safety straps, which serve a crucial function in ensuring the safety of passengers during the boarding and deplaning process. Door safety straps are designed to attach the aircraft door to the fuselage, preventing it from moving or closing accidentally when the jet bridge or air stairs are in place. This mechanism acts as a warning system for the crew, indicating that the aircraft door is safely positioned in relation to the boarding equipment. By utilizing door safety straps, crew members can effectively ensure that the jet bridge or stairs are aligned correctly, thereby minimizing the risk of accidents during these critical operations.

In contrast, the other components listed do not specifically address the issue of placement concerning jet bridges or air stairs. Door safety locks are primarily focused on securing the door when closed, while emergency lights serve to guide passengers during evacuations and emergencies. Cabin announcements provide essential information to passengers but do not play a role in warning the crew about equipment placement. Thus, understanding the function of door safety straps is key to ensuring operational safety in inflight services.