If you have anything to do with aviation you probably heard once or twice the word AUTOPILOT. Nowadays you even hear it if they talk about Cars. Who is this guy called autopilot and how does he log its flight hours? I’ll try to explain you some of the basics below.
The autopilot release work pressure on pilots as they don’t have to directly control the aircraft themselves, the autopilot can follow programmed flightpaths or follow other commands that the pilots give it by turning knobs or put it in an FMS (flight management system). These programmed paths can be flown fully automated and can mostly fly approaches as well, if certificated it can even land itself.
To start, the autopilot can control some basic controls of the aircraft and has different modes it can follow. The most used function of the autopilot is to fly straight and level flight. Some smaller planes already have this option to keep the aircraft level and keeps it at a certain altitude or pitch. With more advanced aircraft it starts to do more and more as it is directly connected with controls of the aircraft.
There are 3 ways an autopilot can control the plane by sending signals to a small motor controlling the surfaces that control the movement: 1 = roll by controlling a small motor that controls the ailerons on the wings. 2 = pitch that controls the elevator and/or an elevator trim tab. 3 = yaw that is controlled by the rudder. And in most modern aircraft an auto-throttle that is coupled with this.
But who is this guy we call autopilot? It’s actually a very small panel that you can find in the middle of the cockpit that can be reached by both pilots. The single button AP is to activate the autopilot. But if you only press this button the autopilot still doesn’t know that it has to do. The pilot still has to give it a command that the autopilot should follow.
Thats why we have all these other buttons. In basis from left to right: FD = flight director it shows you a cross what the modes are doing in the artificial horizon. CRS knob – A course set knob (CRS) is located at each end of the Flight Guidance Panel. These knobs individually set the courses on the left and right displays. The CRS knob sets the course for a VOR radial or LOC course. NAV (navigation) button – The NAV mode intercepts route identified with VOR radials, and intercepts and flies desired FMS tracks. HDG button and knob – Pressing the HDG button engages the heading mode. The heading button controls the heading bug and digital display. APPR (approach) button – The APPR mode is used for almost all approaches, regardless of NAV source or whether a vertical mode is also associated with the approach. I could write a whole blog about this mode. B/C button – The back course button is used for a localizer back course approach. 1/2 BANK button – Pressing this button reduced maximum bank angle of 15° (for all lateral modes, except roll) on both FDs, used on high flight levels and in case of 1 engine out procedures FLC (flight level change) button – This mode basically alters the pitch of the aircraft to
keep a certain speed that you have set with the speed knob. This mode we mostly use during emergencies after take-off. Usually not during normal climbs. SPEED knob – The SPEED knob is used to set the IAS or Mach speeds in the speed tape for FLC mode. VS button – The VS button selects vertical speed mode. When activated, the system maintains the vertical speed reference from the actual give VS of that moment. VNAV (vertical navigation) button – Pressing the VNAV button arms and then captures the FMS pitch steering commands of the Flight Directors if FMS is selected as the NAV source. It now is able to fly the given vertical profile if given in the FMS. ALT (altitude hold) button – When ALT engages, the FD holds the existing altitude at the time the ALT button was pushed. ALT (altitude select) knob – A preselected altitude is set via the ALT rotary knob. The altitude preselect mode provides a means for FD/AP to climb or descend to a preselected altitude, and then level off and maintain the preselected altitude. AP (autopilot) button – Pressing the AP button engages the autopilot. Pressing a second time disengages the autopilot. YD (yaw damper) button – Pressing the YD button engages the yaw damper (YD). The YD can be engaged independently of the autopilot, but the autopilot system does not engage without the YD. XFR (transfer) button – Selects the desired flight director (left or right) to point to the side of the pilot flying mostly.
I almost forgot. In most airlines, the pilots do the takeoff themselves and about 1 minute after takeoff the autopilot takes over and the pilot monitors if the autopilot is doing the right thing and takes over if something goes wrong or the correction is different than the pilot wants. Before landing the pilot mostly takes over. Depending on pilot, aircraft, and company you can keep the autopilot on. The challenger allows us to fly a precision approach on the autopilot until 80 ft / 25 meters above ground.
So that’s more or less everything I can tell you about our autopilot, I hope you found it interesting? If you have any questions about the autopilot system let me know in the comment below.
Ps, I call the autopilot in our aircraft “BOB”. Marshallers have the same name: “BOB”. And all flight attendants are called “MIEP”