RMI Question

[ice2x01]

On the RMI, the pointer arrow head (reference to VOR) represents
a- QDM
b- QDR
c- Radial inbound

I say A.

[CJ Driver]

I hate these style of questions - I hope this is not a real exam question for a 21st century pilot licence, although I fear it may be. :*

1. The Q code was deprecated when VHF voice communications replaced morse code, and should not generally be used, ruling out answers A and B.

2. Answer C is a trick answer, since radials always run "from" the station, so the radial is on the tail, but nobody cares about that distinction in the real world either.

The great thing about the RMI is that interpretation of it is completely natural - the pointer points at the station. That's all you need to know.

Rant Over. Thanks for listening. :ugh:

(In the 1950's, the answer they were probably looking for was A).

[ice2x01]

I completely agree with A. However my classmates are trying to tell me its C because QDM and QDR is only associated with an NDB (according to them).

[bingofuel]

QDM, QDM, QDM , G-XXXX request QDM

Strange, I thought that was still a recognised procedure and has nothing mto do with NDB's.

[Microburst2002]

What is "radial inbound", here?

The pointer of the needle points at the reciprocal of the radial the airplane is . If that is what they mean by radial inbound, that's the one.

It is not necesarily QDM, since VOR radials use the variation of the station, instead of the variation at the airplane's position, so there can be a slight difference.

also, in case of failure of the rotating card, the tail of the needle will keep pointing at the correct radial, so you don't have relative bearing indication.

[milo737]

I say its A

[763 jock]

And those of a certain vintage will remember "Decca" and other such nonsense being studied as part of the ATPL, years after it was withdrawn.:mad:

[EXWOK]

Clue:

There are no radials associated with an NDB.

RMIs are referenced to LOCAL magnetic North.

I think that answers the question, although given the imminent demise of NDBs I concur that it isn't so relevant to the real world of aviation.

Although it does demonstrate a grasp of the essentials, a bit like the DC carbon-pile VR, so does have some relevance to the world.

[dirkdj]

I would say C because ATC will always say 'fly radial XYZ inbound to the VOR ABC' if they want you to proceed to a VOR on a given radial. I have never heard this with reference to NDB.

[milo737]

How does your post answer the question? Which do you think it is, a b or c?

[milo737]

If your flying inbound/outbound from a VOR staton using the RMI instrument, and the controller asks you "what is your current radial" In both cases you will look at the tail of the needle.

The head always points to the station relative to your position, which is the magnetic bearing to the station also known as QDM.

This is why i think it is A

[aterpster]

I've never heard of QDM or QDR until this thread. I guess I am fortunate to not have crashed.:eek:

[Checkboard]

On the RMI, the pointer arrow head (reference to VOR) represents
a- QDM
b- QDR
c- Radial inbound

A - QDM, the Magnetic Direction of the station, measured at the aircraft (i.e. with the magnetic variation at the aircraft.) This is not the correct answer, as the RMI needle presentation is set to "VOR". A VOR produces two phased radio signals, with the phase difference defining the magnetic radial at the VOR. This is the difference between using a needle presentation for a VOR, and using an ADF needle (which is the point of asking this particular question).

B - QDR - the Magnetic bearing from a station. The pointer arrow TAIL would read the bearing from the station. The arrow head is displaying:

C- the radial (as determined by the VOR's signal phase difference, referenced to magnetic north at the VOR station), inbound as you are using the head of the needle. Not good terminology, but the closest correct answer.

[capt. solipsist]

ATERPSTER:

Lucky for you, but i almost did just today, when my copilot, as he went visual at 1000', commanded, "FDs off, set QDF"

WTF...???!!! :ugh:

[Checkboard]

The QDF, he asked for the:

QDF (what is the / here is the ... ) difference in actual height of pressure level to height of same pressure level in ICAO standard atmosphere (the 'D' - factor).

:confused:

... not the "runway QDM", or the QFU? ;)

ICAO Q codes (http://www.pilotfriend.com/training/flight_training/communication/q_code.htm)

[milo737]

You could be correct, they just can output their information properly in this country due to having weak english language.