AFRUs: me or them?

[outlandishoutlanding]

If I make a call on a CTAF that allegedly has an AFRU, and don't get any response, yet I can listen to the AWIS and talk to ATC, do I presume that the AFRU is broken, or panic and think that I've managed to screw up my radio procedures for the airfield?

(at a diversion airfield that I hadn't originally planned to land at)

[717tech]

Could it be that you simply missed the beep that informs you that you're not alone?

I'd make my radio call again and continue to make my radio calls. It could be that the AFRU is playing up but the frequency itself should still work. If you're really stressed that that isn't working, maybe speak on the area... But that's another story that's being debated in another post.

[kaz3g]

It could also just be that someone else activated it a short time before you.

Kaz

CAAP 166-1(3)

7.5.4 At aerodromes with an Aerodrome Frequency Response Unit, pilots will receive confirmation that they are broadcasting on the relevant CTAF. This will be either the name of the aerodrome and the word “CTAF” or, if any aircraft transmissions have been received by the AFRU within the last five minutes, a low volume 300 millisecond tone burst. This helps pilots to both confirm they are using the right frequency and makes them aware of potential traffic in the area (See ERSA Aerodrome Frequency Response Unit)

[outlandishoutlanding]

kaz, I wasn't even getting the beeps. I didn't hear anybody on the radio, either, and the airfield was quite dead. Hence either I've tuned the incorrect frequency (checked twice) or the AFRU was busted.

If the AFRU isn't working, should that be NOTAMed?

[Capn Bloggs]

Yes it should.

Do this on the ground only! If you have two radios, you can check you're on the CTAF/any freq (or your radio is actually transmitting on a particular freq) by transmitting on one set and listening on the other. You'll hear yourself talking. Make doubly sure you reset your volumes and frequencies afterward, though.

[Squawk7700]

I assume you are aware that if you press to transmit 3 times in a row in close succession that the AFRU will read back the name of the CTAF assuming that it's a "proper" one?

[YPJT]

MOs139 14.3.4.1
Operating Performance Requirements of AFRU
When an aircraft operating in radio range of the AFRU makes a transmission (radio broadcast or unmodulated carrier burst) on the aerodrome frequency, the AFRU must be able to detect the presence of aircraft VHF carrier transmissions of 2 seconds or more in duration, and, at the end of the aircraft transmission, it must automatically respond with either one of the following types of transmissions on that frequency:
(a) A pre-recorded short voice message, (normally taking the form of the aerodrome location) if there has been no other received aircraft transmissions in the previous 5 minutes; or
(b) A short (300 ms) tone burst if any aircraft transmissions have been received in the previous 5 minutes.
In addition, the AFRU must also be able to detect and respond to any aircraft transmissions which consist of three sequential carrier bursts over a five second period, with the pre-recorded voice message as at (a) above, regardless of radio transmission activity by aircraft in the last 5 minutes.

[YPJT]

I assume you are aware that if you press to transmit 3 times in a row in close succession that the AFRU will read back the name of the CTAF assuming that it's a "proper" one?

Squawk7700, never seen an improper one? Are there any out there?

[outlandishoutlanding]

I assume you are aware that if you press to transmit 3 times in a row in close succession that the AFRU will read back the name of the CTAF assuming that it's a "proper" one?
Was not aware of that. Will have to test the next time I'm overflying YGLB.

[Squawk7700]

There's one that I know of that's a private one (as in an unlicensed airfield) and it also activates the PAL system when you press 3 times.

[YPJT]

Well anyone can buy one but would be interesting to see if it has been licensed through ACMA and AsA.
AsA usually do the assessment in terms of frequency allocation etc (incl 126.7) then pass it all onto ACMA who issue the licence.
Not an inexpensive exercise to set up a full PAL / AFRU

[gerry111]

My favourite AFRU is at YTGM.

It actually sings back: "Thargomindah aerodrome." :cool:

[Capn Bloggs]

Happiness is arriving at 0645, with the suninmyeyes, and she says the airfield lighting has been energised! :ok:

[YPJT]

I remember speaking to the guy who builds one of the models of AFRUs a few years back. Asked him about who was the voice of "bitching Betty" to which he replied "That would be my wife" :ooh:

They are great units when installed correctly but interesting to hear some pilots who still struggle with the PAL activation side. One second on, One second off x 3 usually does the trick. Don't know about blowing into the microphone though whether that excites the receiver any more than an unmodulated carrier.:confused:
Happiness is arriving at 0645, with the suninmyeyes, and she says the airfield lighting has been energised I have experienced units that have not been configured correctly and that say "....... Aerodrome lighting fail" during daylight hours because it was detecting the RWY edge lighting was not coming on despite activation of the PAPIs.

[Capn Bloggs]

interesting to hear some pilots who still struggle with the PAL activation side.
This is a menace. Some units are very very particular where if you do not get it exactly right, it will refuse to cooperate. Others you can fire three shots and or dawdle your three clicks and they'll always work.

[uncle8]

If you happen to hesitate (take your finger off the mic button?) during your transmission, the AFRU might be responding while you are finishing.
Also, not all AFRUs work at all levels in every direction so, in answer to the OP:
Do not panic.
Check that you are on the correct frequency.
Try another broadcast and continue making normal broadcasts.
If you can confirm that the AFRU is u/s, e.g talk to another aircraft on the frequency, report the matter to the AD operator.

[YPJT]

One other thing to remember is that if the PAL is on its own frequency separate to the CTAF than the code should be 3 x 3 second pulses with a one second gap between. Again some of them are not configured correctly and will work off 3 x one second pulses.

[Centaurus]

Don't know about blowing into the microphone though

'In the Fifties, the RAAF had a flying training airfield at Uranquinty NSW which was 14 miles from Wagga. They operated Wirraways, and Tiger Moths. Later, Winjeels replaced the Moths.
A few miles away from Uranquinty was a village called The Rock because of its proximity to nearby high terrain.

Several trainee pilots got together and arranged to have a dog fight in their Wirraways. Quite illegal and unauthorised but good fun. The Rock, being a well known geographical feature visible for many miles was selected as the venue. A code was worked out by pilots blowing into their microphones (equivalent of Facebook today?)

A Wirraway instructor and his student in the local training area twigged something was up, what with all this blowing through microphones, and soon saw aircraft chasing each other around the sky around The Rock.

He joined the fight hoping to get close enough to read the serial numbers. Suddenly some eagle-eyed trainee pilot realised that one Wirraway he was chasing had two pilots while all the others were solo.

The game was up and after everyone had landed, the CFI was waiting to read the riot act to the culprits:D

[Capn Bloggs]

Well I'll be blowed... blow the AFRU, where's me unicorn? :}

[Ex FSO GRIFFO]

Gorne fishin'.....

[LeadSled]

Folks,
Don't dare mention who built the first AFRU sets in their garage at home, and installed the first one at Bundaberg.
Bundaberg was the first, after a particularly close near hit between two aircraft, in IMC, both pilots were professional pilots, on different frequencies.
That one still sends shivers up my spine, it was so close to a disaster.
Tootle pip!!