Mid-air, near mid-air, and-on ground collisions are one of the most important cause of accident in general aviation. For this reason, engineering an affordable sensor helping pilots in preventing it could be very important in order to prevent accidents. Present sensors, indeed, are very expensive and cannot be affordable for small aircraft and helicopters. The idea of ODESSA (Obstruction DEtection Sensor for Surveillance on Aircraft) is to provide a small, light, and low-cost sensor (comparing it to the present ones) that could be installed on both airplanes and helicopters, but on unmanned aerial vehicles too. This is possible adopting the modular avionics concepts of on-board system independency, reducing maintenance efforts, granting different platform applicability. Using millimetric radar, learning techniques from automotive worlds, gives different advantages. One is that automotive technologies are well tested and reliable. These solutions are small, light and cheap too. Inheriting characteristics from automotive technologies, ODESSA allows to detect small object, increasing on-ground safety during handling and taxing. An issue of these mission phases is the possibility of collision not only with aircraft (that could be minimized by using new generation ADS-B systems), but with other kinds of object (as pushbacks, cars, signals, personnel, birds…) not well detectable from aircraft unless mounting the terrestrial version of ADS-B (that requests the adaptation of the whole airport infrastructure). ODESSA system makes possible that safety in landing and ground procedures is independent from different component of the airport system, granting danger acknowledgment in different sceneries.