CTRL A & O versus the Approach button

[Guest]

I found the CTRL A (glidepath ) and CTRL O ( Course ) buttons veryinteresting as it gives the opportunity to independently interceptfirst the course of ILS and intercept the glidepath when markeris on level position. Procedure is to intercept glidepath from below and move then from level flight into a controlled decend as this much easier compared to dropping and leveling off at glide path - etc. However when using this as a practise the second keysecuence swithes the Aproach button off. Does anybody know how itshould work.. Thanks peter

[wsieffert 0]

Testing these two Keyboard Commands resulted in the following:Autopilot Approach Mode On/Off CTRL+APressing CTRL+A caused the autopilot Approach (APR) light to illuminate and the aircraft conducted the approach to the selected NAV1 ILS runway approach in the normal manner.Pressing CTRL+A a second time during the approach extinguished the APR light and deselected the autopilot approach, as expected.Autopilot Localizer Hold On/Off CTRL+OPressing CTRL+O caused the autopilot APR light to illuminate and the aircraft conducted a heading approach to the selected NAV1 ILS runway approach but did not conduct a glidepath approach.Pressing CTRL+O a second time during the approach had no effect and the autopilot APR light remained lit.Five approaches were made:a. The first approach was initiated by pressing CTRL+O. Prior to the glidepath indicator reaching the On-glidepath marker, CTRL+O was pressed a second time. The aircraft continued on the proper ILS heading but didn't conduct a glidepath approach.b. The second approach was initiated by pressing CTRL+O. After the glidepath indicator reached the On-glidepath marker, CTRL+O was pressed a second time. The aircraft continumed on the proper ILS heading but didn't conduct a glidepath approach.c. The third approach was initiated by pressing CTRL+A. Prior to the glidepath indicator reaching the On-glidepath marker, CTRL+O was pressed. The aircraft continued on the proper ILS heading but didn't conduct a glidepath approach.d. The fourth approach was initiated by pressing CTRL+A. After the glidepath indicator reached the On-glidepath marker and the aircraft started the descent to maintain glidepath, CTRL+0 was pressed. The aircraft continued on the proper ILS heading but glidepath information was lost to the autopilot and the aircraft would have crashed if the flight continued without intervention.e. The fifth approach was initiated by pressing CTRL+A. Prior to the glidepath indicator reaching the On-glidepath marker, CTRL+O was pressed. CTRL+O was pressed a second time before the glidepath indicator reached the On-glidepath marker. The aircraft continued on the proper ILS heading but didn't conduct a glidepath approach. The conclusion of this approach seems to indicate that once the CTRL+O key is pressed, it has no further state, i.e., to turn the autopilot APR glidepath function ON. It can only turn the autopilot APR glidepath function OFF.CONCLUSIONS:The CTRL+A keyboard function turns ON/OFF the autopilot approach (APR) mode correctly. It provides the same function as pressing the APR button on the autopilot control panel.The CTRL+O keyboard function turns ON the autopilot APR light but disables the glidepath function. This condition cannot be duplicated on the autopilot control panel by merely pressing the APR button. This function seems more related to the Autopilot Nav 1 Hold On/Off function (CTRL+N) or pressing the autopilot NAV button.RECOMMENDATION:a. Continue to use the CTRL+A (A/P APR button) function since it replicates the aircraft autopilot functions.b. Discontinue the use of the CTRL+O function since it doesn't replicate any mode available on the aircraft autopilot control panel.

[Guest]

Thanks for all your efforts as they are inline with my findingsbut I have always doubt as I am not an expert in FS nor a pilot.So, considering these CTRL functions I thought there is perhapsa special reason for having CTRL O. Perhaps I could use it atdecision hight for switching of glidepath while maintainingcentreline This gives some time to concentrate on the vertical axe only ...while the engines fireup for a Go Round.Cheers peter de Bruin

[Guest]

>I found the CTRL A (glidepath ) and CTRL O ( Course ) It's really quite simple:Use "APR" CTRL-A when landingUse "NAV" CTRL-O when navigating to/from a VOR.

[wsieffert 0]

If that is the case, what is:Autopilot Nav 1 Hold On/Off (CTRL+N)which illuminates the NAV button/selector on the autopilot. If the NAV button/selector is illuminated, the aircraft will navigate to the NAV1 radio selection, if in range.Autopilot Localizer Hold On/Off (CTRL+O) has no cockpit selector available, which makes it a unique situation.