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cbrjock
09-07-2011, 14:42
Doesn't appear to have its own thread, so here's Waddington's:

5093 5094

canberra
09-07-2011, 16:02
And can anyone confirm what exactly DRDF stands for? I know that its Digital Direction Finding, but what does the R stand for exactly? I have heard a few different things, some say its resolution and some say read out.

AiXAdmin
09-07-2011, 20:41
I thought this was a TACAN or VOR - DRDF is a term I've never heard of.

P Bellamy
09-07-2011, 20:52
This IDT course at Cosford may have some relevance: FGRI 23310 Digital Resolution Direction Finder (DRDF), including the Data Transmit/Receive (DTR) System. (http://www.raf.mod.uk/idtraf/courses/2044.cfm)

All the best,
PB

canberra
10-07-2011, 12:46
DRDF was first installed at Marham in 1980, Im amazed AiXAdmin has never heard of it! And if you ever watch a documentary called "vulcans vixtors and cuba" the piece of kit that marks down the seconds is DRDF.

Dr_Bishop
21-02-2012, 22:27
If anyone is interested, I would be happy to tell you how you did a DRDF approach, which replaced the CADF approach.

AiXAdmin
21-02-2012, 23:21
If anyone is interested, I would be happy to tell you how you did a DRDF approach

Yes please...

Aeronut
21-02-2012, 23:58
I always understood DRDF to stand for Digital Range and Distance Finding ie it gave a range and bearing.

Dr_Bishop
22-02-2012, 08:45
I always understood DRDF to stand for Digital Range and Distance Finding ie it gave a range and bearing.

From an Air Traffic point of view, as a once user, it does stand for the above.

I will post up later this morning, how we Air Traffickers used it. AiXAdmin you'll have to wait a bit...

AiXAdmin
22-02-2012, 10:20
AiXAdmin you'll have to wait a bit...

Spoken like a true ATC bod. :twisted:

Dr_Bishop
22-02-2012, 10:26
Yes please...

An extract from my forthcoming short story:

I am rudely awakened again by the Approach Controller advising me he has a Jet Provost coming in for a DRDF approach. I confirm with him a DRDF approach? Yes, local he wants a DRDF approach… Well a DRDF approach is a Digital Range Direction Finder approach, when an aircraft transmits on the local frequency set for that position, from the kit installed you get a digital reading of the heading (range from the airfield) the aircraft needs to fly to the airfield.
The approach controller gets the JP to free call Binbrook Tower on 310.8, in a second I get the call, MAR10 Binbrook Tower, join for a DRDF approach, Level Flight Level 65, 2 POB. Okay here I go… The aircraft responses are in italics…
MAR10 Binbrook Tower, join for Runway 21 Right Hand, QNH 998, Circuit clear, steer 160, report steady with heading.
MAR 10 steady heading 160.
MAR10 check for transmission.
M10 steady heading 160.
M10 steer 158.
M10 steady heading 158.
M10 check.
M10 steady heading 162 Level Flight Level 65.
M10 indicating in RADAR overhead (I know this as the DRDF is sending me wild headings which are all over the place) turn left heading 050 degrees, descend report level 3000 on QFE 1008. (I now start the stopwatch, all turns etc are now timed by stopwatch and give the aircraft [as it is a jet, okay loosely termed jet] one minute to turn and descend before my next check and next turn. Technically one minute out, turn, and one minute back should bring him back into the overhead to join via high key.
M10 turning left heading 050, descending to 3000 feet on QFE 1008.
M10 check.
M10 heading 050 now level 3000 feet.
One minute has now passed.
M10 turn left heading 212, descend report level 2,500 feet, QFE 1009.
M10 left 212, descend report level 1,500 feet, QFE1009
M10 check.
M10 heading 212 approaching 1500 feet.
M10 check.
M10 level heading.
M10 indicating overhead, are you visual with the airfield?
M10 affirmative.
M10 clear High Key approach, report Low Key with intentions, circuit clear, surface wind 230/15kts.

That is it really, can be difficult with more than one aircraft doing it or you have aircraft in the circuit. If you had more aircraft doing DRDF approaches, then the Director would do them and he would use a ‘stack’ procedure.

This procedure was at its height during the 2nd WW and the earlier 50's. When I was a FISO on the rigs, naughty boy that I was (FISO is a Flight Information Safety Officer, using this approach it was deemed that we controlled aircraft, so breaking the law), I always used this approach in poor weather conditions, as it was the safest and the chopper jockeys had no problem with it, as they new most of us were ex RAF Controllers.

canberra
22-02-2012, 11:26
Aeronut, DRDF (and CADF) did not give you a range ie distance it only gave you a bearing. TACAN gives a range and bearing.

Dr_Bishop
22-02-2012, 12:00
Aeronut, DRDF (and CADF) did not give you a range ie distance it only gave you a bearing. TACAN gives a range and bearing.

Which is why when taught to use the DRDF (same procedures applied with CADF) to ignore everything and say what you see... Remembering to set to steer and not bearing! Bit embarrassing if you had bearing set!

AiXAdmin
22-02-2012, 12:47
Thanks - See if I've got this right...

1. Only equipment required on board a/c is a comms radio. ATC just needs the "QDM machine" and a published procedure.
2. It's a cloudbreak procedure to a visual circuit (ie not a 'non precision' approach to land procedure)
3. ATC directs the a/c throughout the procedure (timings, descent profile and headings) based on QDM responses.
4. No distance information. The only time that aircraft position is actually known is in the overhead.

Who's assessing drift? - ATC or aircraft? as in a stiff wind the a/c would fly to the overhead in an arc.

Essentially this is a variation on what I know as a VHF DF/UHF DF approach - the differences being that it is ATC interpreted/directed and doesn`t position the aircraft on to final for an approach.
Assuming there was a published procedure this kit would allow a pilot interpreted UDF approach to land procedure.

Re the FISO comment - naughty boy.

Dr_Bishop
22-02-2012, 13:02
Thanks - See if I've got this right...

1. Only equipment required on board a/c is a comms radio. ATC just needs the "QDM machine" and a published procedure.
2. It's a cloudbreak procedure to a visual circuit (ie not a 'non precision' approach to land procedure)
3. ATC directs the a/c throughout the procedure (timings, descent profile and headings) based on QDM responses.
4. No distance information. The only time that aircraft position is actually known is in the overhead.

Who's assessing drift? - ATC or aircraft? as in a stiff wind the a/c would fly to the overhead in an arc.

Essentially this is a variation on what I know as a VHF DF/UHF DF approach - the differences being that it is ATC interpreted/directed and doesn`t position the aircraft on to final for an approach.
Assuming there was a published procedure this kit would allow a pilot interpreted UDF approach to land procedure.

Re the FISO comment - naughty boy.

In response:
1. Yes
2. In essence, Yes
3. Yes
4. Correct

The aircraft/pilot assesses drift, you help the aircraft by giving constant checks to maintain the steer to the airfield overhead.

If you do the job correctly and the pilot does what he is told, you can position the aircraft onto FINALS. Hence using my text above, you send the kite out, using the correct rate of turn, you bring the kite back on the Runway Heading.

As for the UDF approach, I have not idea.

Re your comment on FISO, you do the best you can on poor weather. These guys want to go home and if they found out you did not do your best. You swam home!

46MP80
24-02-2012, 10:24
TACAN gives a range and bearing.

Would you elaborate for those not au fait with navaids?

canberra
24-02-2012, 12:08
Ill try!! TACAN = Tactical Air Navigation, its an American system. It gives a bearing and distance (a slant distance to be exact) from the beacon. The beacons are located on airfields and some are part of a chain of beacons which form a TACAN route.

46MP80
25-02-2012, 09:45
I see, so TACAN is an aircraft(airborne) aid and CADF/DRDF is a contollers(ground) aid, your previous post confused me a tad!!

canberra
25-02-2012, 11:08
Thats right TACAN is used by aircraft in the air, in fact fighters use it to find their tankers. The tankers and its chicks had a TACAN set 69 frequencies apart.