Aspects provide for in-situ monitoring of a structure, such as a portion of an in-operation vehicle, by a patch and controller by transmitting, at a first time, a first signal from a first transceiver of a plurality of transceivers in contact with the structure; receiving the first signal carried in the structure at a second transceiver of the plurality of transceivers at a known distance from the first transceiver; determining a baseline signal characteristic of the first signal as received at the second transceiver; transmitting, at a second time, a second signal from the first transceiver; receiving the second signal carried in the structure at the second transceiver; determining a diagnostic signal characteristic of the second signal as received at the second transceiver; and in response to determining that a difference between the baseline signal characteristic and the diagnostic signal characteristic exceeds a threshold, generating an alert.