ok i was watching some flight deck vid and they zoomed into the autopilot area and i saw that it had 3 autopilot switches "L C R" now i think that stands for left, center and right, I thought 1 switch engages autopilot, please explain why theres 3 switches?
2007-10-11 11:32:58 · 7 answers · asked by The Next Ian Poulter 1 in Cars & Transportation ➔ Aircraft
The 757, 767, 747's I've worked on all have L, C, R autopilot switches. They are all turned on when they fly on autopilot but only one is actually doing the job. The other two are backups. If one fails it will automatically switch to another. So three have to fail to disable the autopilot. They have separate switches so that if one fails it can be turned off without affecting the others. There is also a dedicated switch to disengage all the autopilots all at once in case of an emergency. There's one on the autopilot panel under the three switches, looks like a white bar, you pull down to disengage. One on the yoke where your thumbs is.
The three have to be operative for auto-land. Some airports have the capability to interface with the plane and the plane can actually land itself.
2007-10-11 13:20:18 · answer #1 · answered by stolsai 5 · 2⤊ 0⤋
hmm I don't think this is for an autopilot. I think this might be either for a DTU (data transfer unit) for down loading the fms updates every 28 days, or might also be for the FMS;s themselves. There are many "switches" for the autopilot depending upon what you are trying to do. Depending upon the aircraft they may have multiple autopilot computers, however, they typiclly work together, and one acts as the master while the other acts as the slaved unit until needed. You don't typiclly have a switch to manually select a specific autopilot computers... however I have been working mostly with the Honeywell SPZ-8000 and others may act differently. I really don't think they are for the autopilot. If I had a picture of the switch panel, I could give a better answer.
2007-10-11 12:42:29 · answer #2 · answered by Dport 3 · 0⤊ 2⤋
John B and Stolsai covered it pretty well. The only thing that I'll add is that on the early 757s with the autopilot paddles rather than the switchlights, you'd have to manually engage the other two autopilots with localizer capture if you're doing a CAT III approach. With the switchlights installed, the other two will engage automatically with capture, whether you're doing a CAT III approach or not.
Normal operations you're just running around on one.
2007-10-12 02:50:01 · answer #3 · answered by grumpy geezer 6 · 0⤊ 0⤋
Most likely this was not the "Autopilot on/off" switch, but merely an indicator that tells the internal computer which side to gets information from in order to be processed by the flight director.
Both sides are independent of each other in case of an emergency so the captain is "L", the FO is "R", and the backup instrumentation is "C"
The autopilot follows the flight director when it is engaged, but the flight director needs to be told which set of instruments to use.
2007-10-11 12:15:43 · answer #4 · answered by Jason 5 · 0⤊ 3⤋
Only one switch does engage the autopilot each time but it needs to know what it is coupled to. The auto pilot needs to know what it is expected to do. If you want it to follow navigation commands from the captains flight management system then there will be a switch to couple to that FMS. Another will couple to the copilots FMS if it's his leg. There are also heading select modes and such. Without knowing the cockpit configuration and equipment installation it's impossible to be much more specific. Good question though.
2007-10-11 12:40:16 · answer #5 · answered by Anonymous · 2⤊ 2⤋
older aircraft have those switches. basically, one autopilot is flying the aircraft and the other two are backups and they also monitor the primary one to make sure it doesn't do something stupid. in new airliners these days those switches are redundant, there is only one autopilot button.
2007-10-11 19:39:26 · answer #6 · answered by huckleberry58 4 · 0⤊ 0⤋
a book called"Is on autopilot" by capt.julien evans...states that aircraft have a lot of built in redundancy in case of failure!...most things are in threes!!!...like hydraulics/electrics and navigational computers etc...and both pilots have their own set of instruments and controls...with analogue standby basic flying instruments should their digital screens go down....hope this is helpful?...
2007-10-11 11:45:03 · answer #7 · answered by djave djarvoo 'djas originel 5 · 1⤊ 0⤋