top of page

Reliability: Disabling Ambient Fail Exception, Making Alcohol Disappear

Updated: Sep 13, 2022

Tip 45: Study the breath room video and learn everything you can about the breath room and detachment.

Watch for:

Has the qualified technician deliberately moved the breath tube to a location where the ambient fail system is disabled? (the video below)

Has the qualified technician deliberately or negligently disabled the ambient fail system?

Has the qualified technician deliberately or negligently changed zero upwards, much as an individual using a bathroom scale can turn the zero setting wheel to make their weight appear less? (other blog entries)

Have environmental conditions accidentally disabled or desensitized the ambient fail system? (other blog entries)

Have environmental police detachment conditions (radio frequency interference, ambient alcohol, ambient interferent) messed with zero on an infrared (IR) approved instrument? (other blog entries)

It is easy to establish experimentally the phenomenon of disappearing alcohol (or reduced indication as a result of ambient conditions and operator error. (Increased indication through zero floating below true zero is more unusual but can happen with RFI).

The CFS may be willing to concede that ambient conditions can REDUCE the BAC indication on an IR instrument. They will acknowledge under cross-examination that ambient alcohol in the breath room can reduce the BAC indication during a subject test. They will acknowledge that zero adjusts - that zero floats, on an IR instrument. They are less likely to acknowledge that the same phenomeon compromises the scientific reliability of control tests. Can this phenomenon compromise the relability of a control test? Let's run an experiment.

Purpose: To deliberately or negligently disable the air blank test system contemplated by section 320.31(1)(a)

Please think about: Why is there no "ambient fail" exception message during this ACA stand-alone cal check sequence? Why does the cal check appear uneventful and normal (close to target 45 mg/100 mls), even though there are adverse ambient conditions? Why is zero not being adjusted by the elevated ethyl alcohol conditions near the instrument such that the indicated result is reduced by the ambient level of alcohol?

Procedure: The operator has moved the breath tube inlet to a location not contemplated by the design of the instrument.


  1. Intoxilyzer 8000

  2. Dry Gas alcohol standard with target value of 45 mg/100mls

  3. Vodka

This instrument appears to be functioning as designed by the manufacturer. However, the operator has masked the adverse ambient condition such that the instrument is not functioning in such a way as to either flag "ambient fail" and terminate or, alternatively, produce a reliable cal check / reliable subject test. It is respectfully submitted that this activity by the operator renders the control test system (what we are checking on an ACA stand-alone control test sequence or ACABA subject test sequence), not in good working order.

It is arguable that deliberate or negligent operator error that induces an otherwise properly functioning instrument to not function as intended by:

  1. the manufacturer,

  2. the ATC evaluation

  3. and the Minister's approval as "approved instrument"

renders the otherwise "approved instrument"

  1. to cease to be an "approved instrumment"

  2. not be in proper working order per section 320.34(3)

  3. not comply with section 320.31(1)(a)


bottom of page