General:
The reason for the 20mg level is that we can all create small amounts of our own alcohol. This may appear in their blood as an alcohol level, but it will not reach 20mg per 100ml, and anyone who is breath or blood tested to that level is likely to have ingested alcohol in the recent past.
We absorb and excrete alcohol at very different rates. These depend on factors such as sex,
body weight, tolerance to alcohol, and the presence of food.
It is impossible to construct any meaningful chart that an individual can use to predict a future alcohol level after a period of drinking.
Translation: 20mg is the limit for Pilots. It is freely admitted that it is impossible for Pilots to predict a future alcohol level after a period of drinking.
Warning:
Flight crew and cabin crew should not commence duty for at least eight hours after taking small amounts of alcohol, and proportionally longer if larger amounts are consumed.
Although it's likely that if a person consumes a maximum of five units of alcohol dispersed over some hours before the eight hour ban, his or her blood alcohol level will be zero at the end of the ban, it cannot be guaranteed.
Guide: Half a pint of ordinary strength beer (3-3.5%) contains one unit of alcohol),
Translation: Because it is impossible to predict a future alcohol level, we will give you a guide to predict a future alcohol level. Blah, blah, blah…it cannot be guaranteed.
Flyer Flier said:
Anyway, I was at least hoping to get a drink the night 24hours before, but I too am becoming concerned at the low level of the limit at 20mg. Having checked the specs of the various breathalizers on the market, it is apparent that their accuracy is at such a level to be unreliable at the low limits. Even the high tech versions which cope with the driving limit in Sweden (also 20mg) only start at 20mg as the lowest available reading in their range at plus/minus 10mg accuracy.
So we have a new law which admits there is no way for the Pilot to predict when he can legally “fly”.
It sets the benchmark at a limit that is the same as or close to the natural level produced in the human body.
There appears to be no alcohol testing devices that are sensitive enough to detect the very low levels set by the new law.
Therefore, there appears to be no alcohol testing devices that will be available for a Pilot to test himself before going to work so that he may avoid committing a crime.
…and the new law allows an Engineer to work on an aircraft when he is four times as pi55ed as a Pilot!