You can not get much lower than Flt Lt Cunningham's zero level ejection.
DV
Literally no. But in seat terms yes. The subject accident had zero AoB and zero RoD, both of which are highly significant in terms of successful ejection envelopes. Many have died at greater altitude (by definition) than the subject accident but out of seat limits i.e. there is scope to improve on "literal zero-zero".
The Mk12 in the GR5/7 is an example:
Martin-Baker developed the Mk12 seat to provide a cost effective escape system with an improved low speed and adverse attitude recovery capability.
NoD