An important element of the Herschel mission is the concept of Key Programmes, introduced in the previous dedicated pre-launch AO, as a mechanism to ensure that large programmes (in the range 100-1000 hours), requiring a great deal of observing time, could be proposed, selected and executed. These programmes were intended to exploit the unique Herschel capabilities, addressing important scientific issues in a comprehensive manner, generating well characterised data sets of high archival value and the need for follow-up observations.

The three major GT owners, the instrument PIs, were required to spend a minimum of 50% of their GT on Key Programmes, with no specified maximum, while there was no such requirement on the remaining minor GT holders. The outcome of the GT KP process is that in excess of 90% of the total available GT time has been spent in the form of Key Programmes.

Regarding the OT, the HOTAC was free to approve proposals requiring up to a maximum of 40% of the total nominally available OT in the form of Key Programmes and this was actually the amount of time eventually allocated.

In the end by coincidence 21 GT as well as 21 OT Key Programmes were awarded observing time. Altogether in the KP AO cycle approximately 11,000 hours of observing time were allocated. Furthermore, in the GT1 AO process another 550 hours have been allocated in the form of 'normal' proposals.