In the case of the Gatwick LAM SID, for example, would I be right in thinking that if you were to accelerate beyond the 220kts mentioned then you might have trouble keeping the turn tight enough to establish on the DET radial by the required DME distance? Even if not, you would surely make a large turn, possibly heading SE rather than E to get back on the radial if your IAS was too high too soon.. .. .Just as an aside, the NDB procedure for Alderney gives a maximum speed of 110kts IAS. (I know it is an arrival, not a departure!)