We present single pointing observations of SiO , HCO ^ { + } and H ^ { 13 } CO ^ { + } from the James Clerk Maxwell Telescope towards 23 massive star forming regions previously known to contain molecular outflows and ultracompact HII regions .
We detected SiO towards 14 sources and suggest that the non-detections in the other nine sources could be due to those outflows being older and without ongoing shocks to replenish the SiO .
We serendipitously detected SO _ { 2 } towards 17 sources in the same tuning as HCO ^ { + } .
We detected HCO ^ { + } towards all sources , and suggest that it is tracing infall in nine cases .
For seven infall candidates , we estimate mass infall rates between 1 \times 10 ^ { -2 } and 2 \times 10 ^ { -5 } M _ { \odot } yr ^ { -1 } .
Seven sources show both SiO detections ( young outflows ) and HCO ^ { + } infall signatures .
We also find that the abundance of H ^ { 13 } CO ^ { + } tends to increase along with the abundance of SiO in sources for which we could determine abundances .
We discuss these results with respect to current theories of massive star formation via accretion .
From this survey , we suggest that perhaps both models of ionized accretion and halted accretion may be important in describing the evolution of a massive protostar ( or protostars ) beyond the formation of an HII region .