aircanadajet wrote on Dec 22^nd, 2009 at 7:26pm:

Thanks matt: you would not mind if I ask you to point where these buttons are in the cockpit would you? I can see that there is a AP button on the icons and the automatic controls appear. From there I can see a wheel knob, then a bigger wheel knob; which I think it reads pitch down or up, and then the AP, ALT HOLD and Ring DEL and A, B, AB. which ones should I have turn on? thanks!! ::)

Sure - open up the CS Manual #2 to page 57, I'll refer to the number labels on the AP gauge picture shown there. Everything I'm going to say applies to the Autopilot POPUP gauge only...I didn't make any mods to the one built into the pedestal of the VC and I don't use it!

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- Before engaging the AP, you want to be sure that knob #1 is in manual mode, and that switches 3 and 4 are down.  For good luck I generally click #3/#4 on/off once or twice.  Note that when you flip #3 up, #4 goes up too; but you need to flip them down individually.

- Once you are off the ground, if you flip switch #3, both #3 and #4 switches will go up.  At this point the AP has control of the aircraft in all axes.  You will stay "wings level" (or go level if you aren't already) and your nose will stay at whatever pitch up or down that it was when you flipped the switches. This is MANUAL MODE.

1) In this manual mode, you can do a few things:
  a) Use knob #2 to roll the aircraft or pitch it up or down.
  b) Flip switch #4 off and control pitch manually with the yoke.  When you have the pitch angle you like, you can flip switch #4 back on again, and it will hold your pitch.
  c) Flip switch #5 up and the AP will seek and hold the altitude that you were at when you flipped the switch.  Make sure your climb or descent rate is small or the aircraft will porpoise.  Note that if switch #4 was on when you turned on #5, it will switch to the off position.  This is not realistic, but the best I could do with my limited skills.
  d) Flip switch #7 up and the aircraft will turn to fly whatever heading is indicated by the 'heading bug' (orange triangle) on the Horizontal Situation Indicator (HSI). Note that if you adjust pitch using Knob #2 while you are turning toward a heading, the aircraft will temporarily stop turning as it seeks 'wings level'.  Once you stop messing with it, the AP will continue turning toward the heading.

Other modes:

NAV LOC

- If you want to track a VOR radial  or ILS localizer (horizontal navigation only), turn knob #1 to the NAV LOC position.  This has no impact at all on pitch, so you can still do the following actions listed above: 1a (pitch only), 1b, or 1c. When you go to NAV LOC mode, switch #7 will shut off and the heading bug will do nothing.

Note that if it seems like the aircraft will not capture the radial/localizer...try turning off the AP and back on, including rotating the mode knob (#1) to the right and back left to "manual".

AUTO G/S

- Auto G/S is the approach mode you use to track an ILS.  For best results, this is how I do it:

1) Start in manual mode:
- Knob #1 in manual
- Knob #2 at zero bank
- Switch #3 on
- Switch #5 on (holding my intercept altitude); therefore switch #4 off.
- Switch #7 on, holding the intercept heading that I want.

2) As you close in on the localizer, BELOW the glideslope, turn Knob #1 to "Auto G/S".  The aircraft should begin to intercept the localizer, and switch #7 will turn off.  As the glideslope indicator centers, you should see switch #5 flip "off" (#4 stays off) and the aircraft will pitch down to follow the glideslope. Make sure to manage your flaps/throttle/gear so that you aren't getting too fast or slow!

3) As I near landing (or whenever I want control) I hit "z" on my keyboard to shut off the AP (you will hear a buzzer and switch #3 will shut off).

The rest of the landing is up to you at that point.

MAN G/S

- I don't know what that mode does.

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I don't use knob #6 for anything.

I hope this helps with the 'knobology' of my modified Sperry AP.  Knowing how to operate it is only one small part of flying the aircraft successfully.  I recommend you read the CS manuals cover to cover and scrub the web for guidance on how to fly an approach.

Remember:
- Too much or too little speed will hurt you.
- Lowering your gear or adding flaps will generally require you to add power due to the increased drag.  Adding flaps in particular will cause the aircraft to climb temporarily but lose speed in the long run.
- When the aircraft pitches down to follow the glideslope it will gain speed.  
- Due to the 727's relatively low power and spool time, you need to anticipate when you will need power.
- With practice you'll get it!