Max Time for ATC S/by Gen to Kick in?

[mcdhu]

For Airfield ATC guys and gals. In the context of continuity of the Ils signal, is there a max time stipulated (and where) for the s/by genny to kick in, in the event of a mains failure to ATC.
The reason for the query is that the A320 family 'remembers' the signal for 7 secs before throwing in the towel - unless below 200' RA in which case it throws the towel in immediately! I have it in the back of my mind that somewhere it stipulates that the Atc S/b genny should be in within 5 secs.
I would be grateful for 'chapter and verse'.
Many thanks and cheers,
mcdhu

[London Mil]

It has been a few years, but I seem to remember that the change is pretty instantaneous as a back-up battery kicks in until the 'B Centre' is up and running. Someone else may be able to provide 'chapter and verse'.

[Bern Oulli]

At the airfields I have worked at, essential items like airfield lighting, ILS, radar and (of course) R/T were on a "no-break" supply. As London Mil has said, a huge battery of, er batteries supplies those essential services while the standby jenny coughs itself into life. We had a tropical fish tank in the Approach room and even that managed to get wired in to the "no-break" supply.

I seem to remember that the only times the jenny failed to kick in was whenever the system was tested by deliberately chopping the mains. Then it was "cough, cough, f@rt, silence".

[M609]

At our field (And it's supposedly EASA standard in that regard), all navaids, VDF/UDF, radar, radios, all equip. in VCR / APP, and essential radio links. (Radio links to mountain top transmitter sites etc) are on UPS. (Several separate)

Airfield lights are not on UPS, and max startup time for the generators are 16 seconds. Due to that, when visibility drops below 800 meters we start the generators that power the lights, and run the outside main as backup. Switchover time from generators (should they fail) to mains power is 1 sec.
One generator power every second light on the runway and in the approach light systems. Other lights (TWY, signs etc) are split in half geographically.
That way, you still have limited function with only one generator and no mains.

[av8boy]

Also on this side of the pond (generally)... where backup power exists, there's no delay in switching. In fact, in some facilities the only way you could tell you were on generator is that the clocks wouldn't run exactly right. No bump or dim or anything at the time of switch-over.

[vintage ATCO]

Essentially ILS runs on batteries all the time with the batteries being constantly charged by the mains supply. During Cat II/III ops where there has to be less than a one second break during any power failure, generators become the primary power charge to the batteries with the mains supply being the back up.

In the event of failure of one of the supplies (mains or generator) once Cat II/III ops are in you are allowed to carry on for two hours (I think, need to check) before suspending them. However, you are not allowed to start Cat II/III with one supply u/s.

In Cat I where the generators are not running, it can take up to 10 secs to the generators to start and kick in.

CAP168 Licensing of Aerodromes is your bed time reading. :ok:

http://www.caa.co.uk/application.aspx?categoryid=33&pagetype=65&applicationid=11&mode=detail&id=232
(http://www.caa.co.uk/application.aspx?categoryid=33&pagetype=65&applicationid=11&mode=detail&id=232)

[mcdhu]

Thanks everyone for the info.

mcdhu