The measurement of the spectral distibution of radiation from individual points on the earth's surface provides important information of the material composition of those points. To collect data over large areas, it is necessary to use either airborne or spaceborne platforms. In this paper, different approaches to collecting such spectral information from a lightweight airborne platform will be reviewed. The use of spectral tuning technologies such as acousto-optical filters, liquid crystal filters, and linearly variable filters, as well as slit spectrometer systems, will be rebiewed. Features and benefits of each tuning technology and their limitations are presented. Various system configurations are also reviewed as well as constraints placed on system level performance parameters. In particular, trade studies of system level parameters, such as field of view and optical throughput, which are directly constrained by tunable filter technologies, are presented.