49 CFR 563.9 - Data capture.
The EDR must capture and record the data elements for events in accordance with the following conditions and circumstances:
(a) In a frontal air bag deployment crash, capture and record the current deployment data. In a side or side curtain/tube air bag deployment crash, where lateral delta-V is recorded by the EDR, capture and record the current deployment data. The memory for the air bag deployment event must be locked to prevent any future overwriting of the data.
(b) In an event that does not meet the criteria in § 563.9(a), capture and record the current event data, up to two events, subject to the following conditions:
(1) If an EDR non-volatile memory buffer void of previous-event data is available, the current event data is recorded in the buffer.
(2) If an EDR non-volatile memory buffer void of previous-event data is not available, the manufacturer may choose to either overwrite any previous event data that does not deploy an air bag with the current event data, or to not record the current event data.
(3) EDR buffers containing previous frontal, side, or side curtain/tube air bag deployment-event data must not be overwritten by the current event data.