LHRT,
What inbuilt alarms were on these systems?
Here is a very basic and dirty precis on some alarms in TAAATS.With these alarms we get an aural and visual alarm. With the STCA alarm it is a shrill continuous ringing.The others are more of a beep with a break and then more beeping. You must acknowledge these alarms to stop the noise, the visual cue usually a yellow writing will stay on your screen until you either deselect it or the problem is resolved.Alarms can be turned off manually for individual aircraft or parameters changed off line. Open flightplan, open AUR window which shows all alarms, select which one you want to turn off.Make note on aircraft on screen. To turn back on do the reverse. If you turn this alarm off, it will stay off for all sectors in your 'region'. i.e. if I turn it off and forget to turn it back on, the next sector will not have the alarms.
I'm sure I will be picked up on a few things I don't mention.
Route Adherence Monitoring (RAM) A corridor is built along an aircrafts PLANNED route, it can't allow for the landing runway because you don't know when you plan what your landing runway will be. If the aircraft deviates outside this corridor we get the alarm. Examples include when vectoring, aircraft deviating for weather, on approach to aerodromes, etc.
Cleared Level Adherence Monitoring (CLAM) On radar puts a 200' vertical buffer above and below an aircrafts Cleared Level. After maintaining a level if an aircraft deviates by more than 200' of its cleared level an alarm occurs. Also works on ADS-C and B.
If descent or climb profile reduces to a rate that the computer thinks the aircraft is no longer changing level an alarm will occur e.g. Long haul aircraft struggling to get to their planned level. Descending aircraft stopping off momentarily to avoid bad Wx.
Short Term Conflict Alert (STCA) As long as the computer 'knows' at least one aircraft i.e. we have a flight plan (Flight Data Record,FDR). The processors will look for profiles of other targets that will pass close i.e. may be in confliction. Alarm will go off even if aircraft have been given traffic, because the computer will THINK there may be a problem. Should save the day in controlled airspace. Do not turn off as previously unknown aircraft may come in to play as it climbs into radar coverage.
Danger Area Infringement Warning (DAIW) A no go area warning e.g Some military areas or whatever they want to make it. If on an aircrafts heading or climb profile it may penetrate this area an alarm will go off. Even though I have cleared the aircraft to a level below the area or aircraft will turn prior to the area, the computer looks at the climb profile or heading and works out that there MAY be a problem and alarm goes off. Controller may have accidently cleared aircraft to level, or on heading, inside the area and is saved.
LHRT the alarms go off all the time, the situation is usually under control but we get the alarms anyway. There are lots more 'bells and whistles' Minimum Safe Altitude Warnings (MSAW), Missed Position Reports (MPR) specific ones for ADS aircraft. Amended Route Conformance Warning (ARCW) where the FMS Flight Plan doesn't equate to ours.
Estimated Time Over (ETO) where the pilot and system estimate don't agree. There are yet more alarms to tell us that there is a problem with the automatic transfer of co-ordination messages with other centres.
A lot of thought goes into the enabling/disabling of these alarms. If the benefit of the alarm going off spuriously, is outweighed by the time it will save the situation it will stay on. Individual disabling of alarms is not the norm because of the slight chance of it not being re-enabled, or the situation it was disabled for e.g STCA that another situation occurs and the 'protection' is lost.
LHRT there is a lot more to the enabling/disabling of alarms, and their parameters, than the simplistic view that you and Dick have. Those of us that deal with them on a daily basis, under all sorts of situations, tend to be the knowledgeable ones. I hope this has brought some enlightenment. I am now off to watch the AFL GF.
Dick, I have no problem doing what you propose re- MSAW, just give us the training, surveillance and staff to do it. What I don't agree with is your attitude that it is a simple thing to do that 'wouldn't cost anything'.
The pilot accidentally descends, OR the pilot is not on correct frequency, the controller has other situations happening, the pilot gets visual and descends below LSA but doesn't advise centre as he/she is busy or the frequency is congested. The boy who cries wolf scenario develops, there really is a problem, but due to all the 'not real' alarms people become desensitised and the disaster occurs anyway.