Taxi route input - specification or selection?

When providing the pilot with a means to enter a taxi route into an onboard system, readback of the route as displayed by the system allows input errors to be caught. The resulting increase in integrity can only be realized, if the delay between receiving the instructions from ground control and the readback is sufficiently small. Earlier research has explored a taxi route input concept using speech recognition and a concept based on a sequential selection of the successive taxiways and runways. Both concepts were based on pilots specifying all segments that are part of the route. Although rather efficient, the time required by both concepts for route entry limited the possibility to perform the readback from a display of the route. A translation of instructions was necessitated by the fact that the order of the taxiway identifiers in the instruction sometimes varies and that redundant identifiers are often omitted. The input concept described in the current paper does not require the pilot to sequentially enter the full route. Instead, it uses information on common (often occurring) routes combined with input from the pilot to perform an inference of the desired route. This hybrid input combines a specification approach with a selection approach, allowing the pilot to enter a complete route by selecting and/or specifying only a few of its segments. An evaluation of the concept using a simulation of Amsterdam Airport Schiphol, combined with actual ground control instructions, showed that it outperformed the earlier two implementations in terms of efficiency and flexibility.