Global Navigation Satellite Systems (GNSS) are nowadays the most common solutions used to cope with Positioning-Navigation Timing (PNT) applications demands. GNSS are relied on in very diverse contexts and domains, yet the interest in systems such as GPS, GALILEO and Beidou is continuously increasing. However, and in particular for safety critical applications, GNSS are very vulnerable to unintentional interference and to intentional attacks such as spoofing or jamming. GNSS also provide degraded accuracy in dense multipath environments such as in urban canyons. Thus, solutions that could augment, back-up, complement, or surrogate GNSS, are actively sought after. In this paper, we introduce the concept of a hybrid optical wireless positioning system and present the initial experimental positioning results. The system uses optically distributed time and frequency reference signals for synchronization, and wideband radio signals for ranging. Initial results show that decimeter-level accuracy is obtained in urbanlike surroundings.