Are you saying each pitot probe has its own static port in addition to the primary static ports?
No, of course not. Forget ADIRS. Think Cessna GA. What comes down the pitot tube is not just the dynamic pressure of airspeed. Yes it's a dynamic pressure, but comprising BOTH airspeed(A) + static(x). That's why a static line delivers static port pressure to an ASI, now isn't it?...... to offset the pitot-derived static pressure.
To deduce the airspeed (A), the (baro)static pressure(y) from the static ports is deducted from x - in any conventional analogue Airspeed indicator. It's just that, in an ADIRS, it's done using digitized data.
A more confusing way of putting it is: "Airspeed indicators work by measuring the difference between static pressure, captured through one or more static ports; and stagnation pressure due to "ram air", captured through a pitot tube. This difference in pressure due to ram air is called impact pressure."
But in an ADIRU, when the pitot ADM's (measuring x) start showing a significant difference from the static ADM's (measuring y), then there's the increasing possibility of a rejection by various systems (baro hold and TCAS being two of them and the more sensitive).
A case study perhaps? Take the case of a static line containing water. You climb through freezing level and it turns to ice. You continue to climb. What happens to the airspeed? Because the static port derived (baro)static pressure is then trapped at the higher value of a lower altitude, the IAS winds back towards zero. In fact at 220kts it's back to zero within a further 2400ft of climb (been there, done that, got the guernsey). Downward sloped static port with a bung inserted upwards into it. You'd swear it'd never allow water into the lines while parked?
Wrong! Bung had hole in its centre to allow pressures to equalize. Rainwater dripped down over hole and got drawn through bung into static lines as local atmospheric pressure increased with the passage of a front. Airborne passing FZLVL in the climb, you have now lost the altimeter, the VSI zeroes out and your airspeed winds back to zero. Quite frightening when you're in the thick gloop.
In a descent of course the ASI increases as the pitot tube's contribution of static pressure eventually equalizes (and exceeds) at the same height that the static lines froze..... at which point it's over-reading in that descent (until the ice melts of course).
I was quite young when it happened to me and didn't know that the solution was to depressurize and get another cockpit source of static by smashing the face of the VSI. It was the reason why DC4's and Neptunes etc had an ALTERNATE static source switch to tap cockpit air pressure as a fallback static source.
There's a much higher resolution different cutaway diagram of an ASI/machmeter at
this link
.
Rudimentary but hopefully helpful in understanding why clogged pitots can subvert system resolution of static pressures.
.
For a description of operation of an ASI (see
this link)
.