With my SR22 I plan to do Missed Approaches for GPS approaches this way (had no time to do one since the WAAS units were installed).
1. Set MA altitude on the way down, make sure IAS for Autopilot is pre-set to right speed (i used 110 KIAS)
2. 100’ above DA, A/P OFF
3. Arrive at MAP
4. Start Go-around procedure, full power, positive ROC, Flaps up
5. Wait for SUSP indication on GPS1
6. Press NAV (GPSS would work too, but I fly all in NAV)
7. Press ALT+IAS for climb with 110 KIAS.
Assuming you have GNS430W/530W, the only modification I would suggest is delay pressing SUSP if there is an initial climb followed by a turn. Don’t be in a hurry to press OBS. If there is a turn in the missed approach procedure, pressing OBS will generate a Magenta line where the roll out of the turn is completed. If you are not ready to turn, the roll out point will be miss-aligned. If you wait until you have just begun the turn, the roll out point will be perfect.
If you are a type A personality and have to mash something and press the OBS before SUSP is annunciated, particularly if you decide to initiate the missed approach early, you can really mess up your missed approach guidance as the GNS430W/530W will go into OBS mode. The best way to recover from this kind of mess up, is to press direct-to, direct-to, and enter. This will reactivate the final approach leg and allow the normal transition to SUSP to occur again. Then with a little patience, wait if necessary for SUSP, and then use OBS to get the missed approach navigation guidance.
The airplane goes where the pilot points it. If you are using an autopilot, it will follow the commands it is given.
Example, a missed approach procedure instructs the pilot to climb to 2000, then turn left to a fix for a hold that is behind the aircraft. The guidance is to the fix. Unless the aircraft has a fully integrated system of autopilot with MSL altitude input, the pilot has to make the climb and only after reaching the specified altitude, commence the turn to the fix. If you select the missed approach guidance before you reach the altitude, say right after the initial pull up, the magenta line will begin at a point assuming you are starting the turn right away, which you are not. If you delay the pressing of the OBS until the pilot has climbed to 2000, then the magenta line will be established where the turn from the altitude is permitted. Guidance in the turn is not provided, the guidance is to the fix and allows for the turn to be accomplished. If the autopilot is engaged, it will turn you back to the fix.
Look at this approach plate please, this is the RNAV 27 approach of EDMS, one of the places where I use the IAP often.
Wouldn’t a WAAS GPS with the DFC90 A/P guide/fly me through the whole MA procedure INCLUDING the turn?
If I may chime in (NCYankee knows all this stuff better, but I’ll try to clarify). The “whichever is later” part in “Climb on track 274° to MS491 or 3500’, whichever is later” cannot be interpreted by all GPS systems, as they need barometric altitude information for this to work. This is what NCYankee was referring to.
In the Perspective where I did my IR on, baro altitude was available, but most smaller GA planes (including your installation I guess) don’t have it.
If you make 800 fpm in the climb, then you will have climbed more than 2500 ft in 5.9 nm at 110 knots GS, so it shouldn’t be a practical issue here.
That was the missing part I guess … thank you!
That means that I should press “OBS” after overflying the MS491 waypoint – or after reaching 3500ft. Got it. Because if I press OBS too soon the GPS will interprete that as having reached 3500. Correct?
Some things are so simple once you understand them ;-)
I’d also be interested to know if you should use OBS mode on an RNAV approach in this case or let it auto sequence, as I don’t know the answer.
You mean it could/should be enough to simply press “NAV” (or GPSS) again to start the sequencing again?
When I have time before XMAS I’ll fly that approach ten times ….
No, I was confused as to the buttons being used. Actually you press the OBS key just to un-suspend navigation and activate auto-sequencing. I thought that was another button and that NCYankee was suggesting using OBS mode on the missed approach holding point after un-suspending to manually set the inbound course. My bad.
