The FLAP scheme works as follows:
- A distance account, analogous to a bank account, is opened for every
traveller. Each account has a balance in kilometres, which starts at zero.
- Airlines withdraw the distance of each flight from the traveller's account at
check-in.
- The "daily allowance" defines a total distance in kilometres. The account of
every overdrawn traveller is credited with an equal share of the daily
allowance at the start of each calendar day.
- Overdrawn travellers are not allowed to start a new trip, with airlines
refusing any attempt to check in.
Lowering the daily allowance over time has the effect of lengthening the time
between trips and thereby reducing air travel. Sharing the daily allowance out
between those travellers in deficit is equitable but at the same time allows for
continuing variability in the distance flown, both by individuals and overall over the
course of each calendar year.
The concepts of “trip” and “clearance promise” add the additional flexibility needed
to make the scheme practicable and low impact for all types of traveller. They work
as follows:
- A trip is defined as any sequence of consecutive flights by a single
traveller with a maximum length of 90 days from the start of the first flight
to the end of the last.
- Travellers (or the airlines they fly with) are able to submit the details of a
planned trip to FLAP in advance and obtain a clearance promise. This is a
committed date after the completion of a specific trip when the traveller is
allowed to fly again. regardless of their distance balance.
- Consecutive clearance promises can be "chained" to allow clusters of trips
close together in time. Chained promises have a date that is artificially
brought forward to accommodate the next trip. Chains have a maximum
length, with the date of the last promise pushed further into the future to
compensate for the distance deficit accrued over the length of the whole
chain.
The overall effect of the system is to enforce a decreasing limit on how much
distance is flown:
- Without placing a direct restriction on how much any one person can fly.
- Whilst applying the same rules apply to all travellers, regardless of how
often they fly.
- Without levying taxes or making use of any other kind of financial
incentive.
In order to make the service work as a voluntary service 10,000 simulated users (bots) created load on the system. These bots travel at varying frequencies to simulate real-world travel patterns and their travel frequency declines over time at the same rate as the daily total.
For more details on the thinking behind flap please refer to this white paper or the FLAP website.