The block fading channel model is very useful for many systems in urban environments. When striving for high performance implying high rate, full-diversity and excellent coding gain, coded modulations have to be used. When linear precoding is used, error-correcting codes can focus on achieving a high coding gain and are not constrained in coding rate so that no bandwidth is sacrificed. However, optimal precoding schemes for coded modulations on block fading channels are not known because of the inability to deal with the randomness of the fading gains. We study coded modulations for block fading channels in the fading space. This geometric approach yields more insight and allows to take into account the randomness of the fading. It can be used to generate the system parameters so that the word error rate performance approaches the outage probability closely.