My government issued document that details the flight list for three days ago, shows that two British Airways flights and one BMI flight were fitted with the chemicals and dispatched on their scheduled flights.
That particular day, the met office suggested dispersing the chemicals at an altitude of 34,000 feet as the wind and temperature layers of the atmosphere were conducive to spreading the chemicals over the entire English countryside over a period of two hours.
To ensure the maximum number of people sprayed they flights departed between 6:30am and 8:00am, every half hour along the same route.
There are only certain days and certain flights that we can release the chemicals, as only a number of pilots and air traffic staff are trained to perform these flights.
The effects of these chemicals are usually seen within 24 hours and so far they work very well at controlling the population. Eventually we will be able to spread these trial flights to more as we can get more air traffic staff and pilots through the security checks.
I hope this does help somewhat..