Measurement-based analysis of software timing behavior provides important insight and evidence for flight certification of modern avionics systems. For multicore systems, however, this analysis is challenging due to interference effects from shared hardware resource usage. We present an approach to multicore timing analysis that uses interference generators to stress interference channels in multicore systems. The test methodology comprises two steps. First, platform characterization measures the sensitivity of the hardware and RTOS to targeted interference channels using a combination of interference generators. Second, software characterization measures the timing behavior of instrumented applications while interference is generated on shared resources.