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AIRAC (Aeronautical Information Regulation And Control) cycle calculations for Ruby.



This gem is cryptographically signed in order to assure it hasn't been tampered with. Unless already done, please add the author's public key as a trusted certificate now:

gem cert --add <(curl -Ls


Add the following to the Gemfile or gems.rb of your Bundler powered Ruby project:

gem 'airac'

And then install the bundle:

bundle install --trust-policy MediumSecurity


You can use this gem in your Ruby project:

cycle ='2018-01-01')         # => #<Date: 2017-12-07>
cycle.effective    # => 2017-12-07 00:00:00 UTC..2018-01-03 23:59:59 UTC           # => 1713
(cycle + 5).id     # => 1804
(cycle - 5).id     # => 1708

The cycle can be formatted similar to Date#strftime, however, the placeholder %i represents the AIRAC cycle ID:

cycle ='2018-01-01')
cycle.to_s                            # "1713 2017-12-07"
cycle.to_s("@%i as per %b %-d, %Y")   # => "@1713 as per Dec 7, 2017"

The current AIRAC cycle scheme started on 2015-06-25, therefore any calculation which leads to dates prior to inception will cause an error:

(cycle - 100).id   # => ArgumentError

The AIRAC::Cycle class implements Comparable and its instances can safely be used s Hash keys.

If you prefer to do the math on the shell, the airac executable is your friend:

airac --help


To install the development dependencies and then run the test suite:

bundle install
bundle exec rake    # run tests once
bundle exec guard   # run tests whenever files are modified

You're welcome to submit issues and contribute code by forking the project and submitting pull requests.


The gem is available as open source under the terms of the MIT License.