I didn’t remember we were talking about an LPV approach. In which case this doesn’t even make sense:
Flyer59 wrote:
Just press “ALT” at the Decision Altitude and the plane will proceed to the M at that altitude.
BTW, what’s “the M”?
Look at the thread title ;-)
M is the Missed Approach Point on the LPV Charts by Jeppesen
No, the Missed Approach Point on a precision approach and an LPV approach is defined as follows: “The MAP on a precision approach is reached when the aircraft reaches the decision height prescribed for the approach while maintaining the glideslope”.
I think you are mixing NPA and PA procedures. That is why I thought you were writing about a NPA here. I maintain that this is wrong:
Just press “ALT” at the Decision Altitude and the plane will proceed to the M at that altitude.
You have to start the climb immediately upon reaching DA and not being visual with the runway.
If you’re on an LPV approach, then once you have captured the glidepath, you should set the altitude bug to the missed approach altitude. Pressing ALT wouldn’t have you flying at decision altitude (luckily).
Yes, I made a mistake here. The “M” at the theshold is valid for the NP approaches, and the Missed Approach for the PA starts at the DA .. sorry, I got it all mixed up.
For the NPA you could press “ALT” to proceed, that’s what I really meant before I got confused ;-), for the PA you could stay in NAV, dial in the new altitude before reaching DA and go around.
You might want to confirm the type and timing of the guidance on the missed approach. I believe that when SUSP is annunciated, you still get lateral CDI guidance that can be used in a Nav mode on the autopilot, but that GPPS or roll steering is not available. I believe you need to press OBS in order to obtain the roll steering from the GNS, but I am not positive and would have to confirm with a flight test. CDI guidance will allow the track to be followed in a conventional Nav mode. If roll steering is not available, the autopilot should maintain wings level, but not make any corrections for winds or turbulence, as it would not have anything to use for tracking. On some autopilots, probably the Avidyne, it should figure out that there is CDI guidance and no roll steering in a Nav mode, in which case it would track the final approach course. This is something I would flight test to confirm.
On an LPV, at the DA, you make your go around decision and commence the missed approach climb. However, you will have some distance to go (0.6 NM or more) before you will see SUSP annunciated. If you mess up and press OBS before SUSP is annunciated, it will put the GPS into OBS mode, which is not desired and the system will not sequence to the missed approach guidance. If you are like me and are a type A personality, and have the “just gotta mash a button syndrome”, that erroneously puts you into OBS mode, press Direct-to, Direct-to, and enter to restore the approach on the final approach path and allow the normal sequence to SUSP, at which time you can then press the OBS button to get your missed approach guidance.
that’s the interesting part, thank you. The part between DA and the SUSP annunciation was not clear to me, and I will have to make a couple of flight tests to really get the right sequence into my brain …
As I understand it now I will arrive at the DA, and if I want to proceed on autopilot I will have to switch it to HDG first (to be able to leave the glide slope upwards) and then VS+ALT to start the climb to the first MA altitude. Then I’ll check for the SUSP indication and after I get that I can proceed straight ahead with the NAV mode of the autopilot. Only when reaching 3500 and the waypoint, whichever is later, I will press OBS to unsuspend and then the autopilot will take over and fly the turn to the fix
(Or I could also press OBS after I get SUSP and stay in HDG mode until i am ready for the turn and then press NAV?)
Doesn’t matter, or does it?
After consulting with some Cirrus specialists in the USA, i understood it, finally …
When you are arrive at the DA on the virtual glide slop you have already set the first Missed Approasch Altitude. If you now simply push VS+ALT it will stay in NAV mode but wipe out the glide slope and climb. I was not aware of this, but this way you can leave the A/P on, wait for the SUSP indication and when the criteria for the turn are met (3500/Waypoint) simply unsuspend the GNS with the OBS key and it will turn …
Now i have to test it …
