satpak77

Anybody know how to program a user defined waypoint (via lat/long) into the G1000 and then define/build a 360 degree orbit around that waypoint ?

Lets say photo-pilot Larry is hired to talk pics of the new golf course community being built. He has the lat/long and wants to put into into his G1000, calling it "GOLF" or whatever the G1000 will accept. Now, Larry wants to build a 360 degree circle, at 3 miles, around this point, and wants to auto-pilot to fly the circle while he is out the window taking photos.

No SAR package installed, rental G1000 airplane

Thanks

FlyingNasaForm

The G1000 can't even draw a hold, let alone do this. Now a collins FMS designed in the 1970s can do you what you are looking for and display it on the MFD but won't drive the CDI.

I would suggest using SkyVector: Flight Planning / Aeronautical Charts or somthing to create 8 lat/long way-points and plug them in the box. Keep the GPS in OBS move so they waypoints don't sequence, he can just navigate using the MFD.

Aviator89

not sure you cant do it. your best option may be to create the user way point and do an oldschool pivotal altitude calculation and go for it if you are ok with some changes in altitude. you cant "create" the circle on the map so no AP help there.

also, i guess you could also just create a hundred user waypoints around the primary target, type them in manually into the Flight plan, then maybe it could do it. But it would be a 100 sided circle (hectagon) or however many u choose. If they are close enough the G1000 may do turn anticipation. But im not sure.

Cubdriver

It can be done but there is some thinking involved. In a Cessna 172 or similar airplane, define a user waypoint using using the typical way, for example in the diagram below I would define "waypoint" as 35 DME on the 90 deg. radial of ABC VORTAC. Then I would set up a hold there (G1000 does holds) and specify zero for the leg length. The flight director will do this, but the trick is placing your user defined waypoint where the orbital center you want results.

That's a tad tricky, but to locate the user waypoint properly so it results in an orbit around some nearby center, you need it to be about 2900ft radius from the desired center, and at a right angle to the radial you used. The AP will do standard rate right turns holding at the user waypoint fix, so with zero length legs it will result in a circle around your orbit point. At about 100 knots in a Skyhawk you will see about 17 deg. bank angles for standard rate, which results in a radius of 2900 ft.

USMCFLYR

I recently did this 'old school style' as Aviator said.
REAL old technology on the GPS unit - so nothing like a G1000 or any type of FMS.

We didn't have the technician with us so we couldn't input the NAVAID into the system and then use the RNAV to build the orbit (25nm in the case) - BUT again went old school.

I used the lat/long of the NAVAID and then built 36 wypts around it using the rad/DME function.
GOLF 090/3
GOLF 100/3
GOLF 110/3
and so on.

Not the way we would usually do it, and out at our distance it was a nice arc. In at 3 might be a little tight and choppy, I don't know.

Blackwing

You can't program in the arc with a single waypoint, you have to define it with a series of waypoints. For a 3 nm radius, waypoints projected every 20° will give you 18 waypoints and straight segments roughly 12-15 seconds long at 100 kts. I've set up arcs with up to 36 waypoints and that yielded a fairly precise arc but still one with short straight segments. If you have multiple targets, do note that a flight plan won't store more than 99 waypoints.

You might consider Roll hold + Alt hold as an alternative; when roll hold is engaged, you can set a bank angle you want to maintain by holding the Control Wheel Steering button on the yoke, rolling in the desired bank, then releasing the button. I think the bank angle has to be >10° for this to work, but it works pretty well. I've used this trick a bunch of times when I've been held outside bravo waiting to get in.

But: why not just use another pilot to fly while he shoots the pics?

Cubdriver

Looking through some references it appears the G1000 only depicts holds on published IAPs, and my advice would apply only to the G3000. Sorry about that. G3000 allows holding anywhere on request and I think my method would work on that machine. The only other method would be some sort of waypoint assortment as others describe. Since that method is certainly not convenient, I do not think there is any way to do this on the G1000 with AP engaged. You might treat it as a DME arc around a user waypoint and hand fly it though. That's easy enough with the virtual HSI it has.

Aviator89

Got another solution, make a single use way point and do a DME Arc around it as if it were a VOR. Should be able to using OBS mode and the course selector. Problem solved.

edit: I see cubdriver had the same idea above. Didnt see it til now. But it may be the only easy way. U could use the AP in Heading mode and still use the AP during the arc.

Aviator89

Nice, the other thing he could do if its a calm or calm(ish) day just do the calculation for bank angle and GS needed for a 3NM radius. Like u said, roughly 17 degrees at 100kts