The ALPA Flight Time/Duty Time Committee believes the definition of flight time limitations in civil aircrew is based on two fundamental principles:

• The first is that the duty schedule should not prevent the aircrew from ensuring that they are fully rested at the start of each duty period. Particular problems can arise when duty periods encroach on the normal sleep time, or when the normal sleep pattern is disturbed by time zone transitions. In these circumstances the provision of adequate time for rest is essential.
• The second principle is that the duration and timing of individual duty periods must enable the aircrew to maintain acceptable levels of alertness at all times.