I've been doing some analysis of the flight data.
First up is the altitude graph.
View attachment 609899
Zooming in on apogee:
View attachment 609900
The Blue line is the raw reported baro altitude using the on-board sensor, and converting pressure to altitude using the standard atmosphere model. The standard atmosphere model is a set of equations that is intended to represent the average atmosphere over all seasons and latitudes. It typically under-estimates altitude for U.S. latitudes during seasons we normally fly, and the warmer it is, the more it underestimates.
NOAA flies weather balloons from dozens of locations across the country, twice per day. These weather balloons carry a GPS receiver to measure altitude and winds aloft, and pressure, temperature and humidity sensors. You can look up the data from these balloons here:
https://weather.uwyo.edu/upperair/sounding.html
For this analysis I used the Grand Junction CO weather balloon data for October 15 12:00 UTC (6 AM local time). Using this data, the balloon-based baro altitude in the orange line matches pretty well with the on-board GPS data.
The on-board GPS data is the most accurate and reliable of the measurements for this flight. The GPS receiver had a lock pretty much throughout the flight, and was tracking 15 satellites before, during and after apogee. This is the measurement that the records committee will use if they accept the record application
The third independent sensor is the inertial navigation estimate derived from the accelerometer and gyro data. This estimate depends on the validity of the acclerometer calibration and linearity, and the attitude calculated from the gyroscopes. For this flight, the gyro sensors hit the rail partway at the end of the burn:
View attachment 609901
Despite that, the inertial navigation estimate agreed with the onboard GPS within about 3.8%, which IMO is pretty good.