First, the take-off warning — Page 156, Lesson 208

Let’s pick this up right where the aircraft is sitting on the runway, ready for take-off. I want to walk you through the take-off warning system and the landing gear warning horn, because these are two separate audible warnings that protect you at the two most critical phases of flight. First, the take-off warning. This is an intermittent warning — it sounds in a pulsing, on-off pattern, not a steady tone. It activates when the aircraft is on the ground and the forward thrust levers are advanced for take-off. So the trigger is: you’ve pushed the throttles up for take-off, and the system checks a list of configuration items. If some or all of the following conditions exist, the warning sounds. Let’s go through each condition, because each one is a specific configuration error you must know cold. First, the stabilizer trim is outside the safe range. The stabilizer is the horizontal surface at the tail that trims the aircraft in pitch. If its setting is not within the computed safe envelope for take-off, you get the warning. Second, the trailing edge flaps are not in the take-off position. The trailing edge flaps are the high-lift surfaces on the back of the wing. For take-off they must be set to a specific position — if they’re anywhere else, the warning sounds. Third, leading edge high lift devices are not in the take-off position. These are the slats or leading edge devices on the front of the wing. They also have a required take-off position, and if they’re not there, you get the warning. Fourth, the speed brake lever is not in the down position. The speed brakes are the spoilers that destroy lift and increase drag. For take-off they must be stowed — lever down — and if it’s not, the warning sounds. Fifth, all doors are not fully locked. This means every passenger door, cargo door, and service door must be closed and locked. If any one of them isn’t fully locked, you get the warning. Sixth, flight controls are not fully unlocked — and this applies only to aircraft fitted with internal control locks. Some aircraft have a locking mechanism that holds the control surfaces in place while parked. If that lock is still engaged, the controls can’t move freely, and the warning sounds. Now here’s the key operational point: the warning indication is cancelled when the incorrect setting is corrected. So the system is not a one-shot alarm — it continuously monitors, and the moment you fix the offending item, the intermittent warning stops. That’s your feedback loop: advance the thrust levers, hear the intermittent warning, correct the configuration, and it silences. Now let’s move to the second warning, the landing gear warning horn. This one is a steady warning horn — a continuous tone, not intermittent. It alerts the pilots when the aircraft is in landing configuration and any landing gear is not down and locked. So the scenario is: you’re configured for landing — flaps set, gear should be down — and if any gear leg is not down and locked, the steady horn sounds. And here’s the important extension: the landing gear warning horn is also activated by flap, speed, and thrust lever position. That means the horn isn’t only tied to the gear itself. If you’re in a configuration where the flaps are set for landing, or your speed is too low, or the thrust levers are in a certain position, and the gear isn’t down and locked, the horn will sound. So the system cross-checks multiple parameters — flap position, airspeed, and thrust lever position — against the gear state, and any mismatch triggers the steady warning. So to summarise the contrast: the take-off warning is intermittent, triggered by advancing thrust levers on the ground, and it checks trim, flaps, leading edge devices, speed brake, doors, and control locks. The landing gear warning is steady, triggered when you’re in landing configuration with gear not down and locked, and it’s also driven by flap, speed, and thrust lever position. Two different tones, two different phases, two different sets of configuration checks — and both are there to catch a configuration error before it becomes a problem.