P2J, your point is valid and agreed with. No official conclusions to be drawn on data recovered from FR24 amateur/DYI channels. It is not designed for such purpouse neither certified.
Yet you know well, that on your A/C, the DMC feeds ADIRS data to QAR, FDR and the ADS-B out unit. Unless the transport layer - FR24 - corrupts or adjusts that data, all readouts will eventually turn out to be the same.
Case study:
A) Unofficial source "FR24" overlayed by an anonymous internet enthusiast (me) over non-purpouse built resource "Google Maps":
pence_googleoverlay.png
B) NTSB findings:
Pending
C) Unofficial source "photography" taken by a non-licenced, commercial journalist:
2016-10-27_N278EA_B737_EA_PEnce-Trump@LGA_ACC2.png
1445yso.jpg
Now
, everybody's welcome to not draw their own conslusions.
Overlay of FR24 recorded positions where ALT = 0.
pence_FR24overlay.png