Bendix/King KAP140 Autopilot

[HPNPilot1200]

Here's a question for those that have a KAP140 AP (2 axis w/ altitude preselect) installed in their airplane or one they fly.

So you're climbing through 2,500msl for 5,500 (cruising altitude for this flight) and you engage the autopilot by pressing the [AP] button which automatically activates the ROL and VS modes. You have selected 5,500 in the altitude preselect, but your dummy brain has your hand to push the [ALT] button instead of the [ARM] so the plane starts to level off while you're still in the climb. You hit [ARM] then [ALT] then [UP] to set a 500 FPM climb to 5,500 but the plane doesn't do anything, it still levels off. What buttons and combination thereof will cancel the altitude hold and initiate a climb to the preselected altitude?

Thanks!

 

[TangoWhiskey]

Jason, when you press the [ALT] button on the KAP140, it latches (as you know) on to the "reference altitude", which is the altitude at the moment you press the button, NOT the "altitude hold" reference you had preselected.

To continue a climb to a new altitude, simply dial in a new altitude with the altitude select knobs, then press the vertical trim [UP/DN] buttons to select the new climb rate you want. It will climb at that rate until it reaches the pre-selected altitude hold reference.

Simple answer, then, twist to select new altitude, then press the UP button 3-5 times.

The "twist first" is important; if you simply press the UP/DN buttons when ALT is already selected, the autopilot will adjust the reference altitude (baro) up/down 20 feet. This is useful when you find yourself in the situation where you have the same baro setting in the Altimeter and Autopilot, but the Altimeter shows you at 5,960 feet instead of 6000, even though you have 6000 dialed in on the autopilot and ALT mode is engaged. Just press UP twice to "adjust" up 40 feet (2 presses x 20 feet each) and you'll be at 6000 on the gauges and autopilot.

I think you can also press the CWS button on the yoke (if you're flying a plane like the late model Cessnas with Control Wheel Steering) and command a pitch up (it will show the VS you're "selecting" on the VS window of the KAP140), and when you release the CWS button it will capture the newly selected VS, ARM altitude hold, and capture the pre-selected ALT when you reach it. I have yet to try the CWS button in that mode, though. If it really works that way, it might be even more "natural" than reaching over and pressing [UP] several times.

 

[flyersfan31]

My late model Cessna doesn't have CWS.

Alternate KAP140 solution: keep punching buttons 'til you get the solution you want!

The KAP140 is a good AP. Works well when you've got it under control. From an ergonomics/human factors perspective, I'm not so fond of it. TW gave a good answer. I was pounding the buttons on mine today and not getting satisfactory responses, and I've only been away from it for 3 weeks. In my defense, I only have about 12 hrs in the plane at this point. Still, I think it would be a stretch to call it intuitive.

 

[Bill]

The KAP140 is a good AP. Works well when you've got it under control. From an ergonomics/human factors perspective, I'm not so fond of it.

You obviously haven't flown an S-Tec 55x with the seperate little altitude selector annunciator, THAT thing is impossible to learn to use without RTFM. The KAP-140, OTOH, is quite easy to figure out on the fly, so to speak. Easy, even.