No, the BMP280, the barometer.
I know, it's a bit strange...so I'm going to explain my project.
My system is an arduino that uses the BMP280 to read the altitude and, when the altitude pass a certain treshold, it starts to log data on an sd card until the altitude gets again below the treshold. I thought that this doesn't work because on ground (with false data) the system works...while it's in flight (in an airplane) it doesn't though. I'm thinking that the problem can only be the g-force or something else that I don't know, do you have any idea?