What is the minimum instrumentation an aircraft needs in order to legally fly ifr? The fs9 DC3 has no transponder, which I would think would disqualify it right there. Even if it had a transponder, it has not dme capability and no course deviation indicator on the vor needle. If this were a real plane would it be legal to file an ifr flight plan?While we're on the subject, what's up with the rmi? A needle tuned to an adf signal will always point at the source of the signal regardless of what the compass card is set at. If you tune to a vor, however, the needle will rotate with the compass card. Why the difference? Since the vor needle has no cdi, what's the point of being able to rotate it? Seems to me it would make more sense to have the vor needle always point towards the source, just like the adf needle.Sidney Schwartz KPDX

FAR Part 91, Subpart C - 91.205The rmi uses a flux gate compass. As such, the compass card rotates as the aircraft rotates or turns. In an aircraft with an RMI, there is no adjustment to correct the Heading Indicator or HSI since the flux gate compass drives the RMI and HI/HSI compass cards. The needles for both ADF and VOR point toward the NAVAID.Try this: Load the B737-400 at an airport that has a VOR and ADF nearby. Select the proper frequencies for the NAVAIDS. Select the slew mode (Y), raise the aircraft above the ground (F3/F4 and F2(STOP)) so the NAVAIDS are indicating on the RMI and HI/HSI, if desired. Use the Num Pad keys (1/3) to make the aircraft rotate around the spot. Watch the RMI and needles. Use the map view/GPS to watch the orientation of the aircraft with the NAVAIDS, for reference.W. Sieffert

Additional information. I was assuming you were talking about the Dual Needle RMI found in the B737-400, I may have missed your point. Here are a couple of websites explaining the different gauges:http://www.thaitechnics.com/nav/adf.htmlhttp://www.allstar.fiu.edu/aero/RMI.htmW. Sieffert

>The rmi uses a flux gate compass. As such, the compass card>rotates as the aircraft rotates or turns.The compass card on the DC-3 does not rotate as the aircraft turns. Too old, I guess. :)Sidney Schwartz KPDX

Nor does the compass card in the C-172. You can manually rotate it.The C-172SPs I have been flying don't even have an ADF gauge. You can pull it up through the GPS Multifunction display, however.W. Sieffert

>What is the minimum instrumentation an aircraft needs in>order to legally fly ifr? The fs9 DC3 has no transponder,>which I would think would disqualify it right there. Even if>it had a transponder, it has not dme capability and no course>deviation indicator on the vor needle. If this were a real>plane would it be legal to file an ifr flight plan?>>While we're on the subject, what's up with the rmi? A needle>tuned to an adf signal will always point at the source of the>signal regardless of what the compass card is set at. If you>tune to a vor, however, the needle will rotate with the>compass card. Why the difference? Since the vor needle has no>cdi, what's the point of being able to rotate it? Seems to me>it would make more sense to have the vor needle always point>towards the source, just like the adf needle.>>Sidney Schwartz KPDXTo answer your question regarding minimum IFR or legal to fly in instrument meteorlogical conditions the minimum is VFR +1. Attitude indicator2. Altimiter3. Clock4. Magnetic Compass5. 1 Radio6. Any of the navigation equipment necessary for the route of flight7. 1 Altitude encoding transponder8. Turn coordinator / Turn and bank

In addition to those instruments you also need:gyro heading indicator (in addition to a magnetic compass)outside air temperature gaugepitot heatalternate static sourcevacuum indicatorvertical speed indicator

>Nor does the compass card in the C-172. You can manually>rotate it.That's because the vor's in the C-172 have course deviation indicators; you rotate the card to select a radial and the cdi tells you if you're to the left or right of the radial. The vor needle on the DC-3 has no cdi, therefore you can't select a radial. So again, a) what is the point of having the needle rotate with the compass card, and :( why doesn't the adf needle also rotate with the compass card? :-hmmmSidney Schwartz KPDX

OK. Thanks to everyone for the information on ifr equipment. That part makes sense, but I still can't figure out why the rmi on the DC3 works the way it does. Maybe no one knows. :)Sidney Schwartz KPDX