The invention relates to a locking
system for locking a door in a closed position relative to a carrier, a door and an aircraft. A locking
system (20) for locking a door (15) comprising at least two locks (31). The locking
system (20) has a
position sensor (40) for each lock (31), each
position sensor (40) emitting a measurement
signal carrying a locked state or an unlocked state of the associated lock (31), the
signal system (30) comprising a controller (50) receiving the measurement
signal and connected to an alarm (60), the controller (50) is configured to issue an unlock signal (SDV) when at least one measurement signal carries an unlocked state of the associated lock, or to issue a lock signal if each measurement signal carries a locked state of the associated lock, and the alarm (60) generates a visual unlock alarm after receiving the unlock signal, and a visual locking alarm is generated after the locking signal is received.