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View Full Version : Help needed Technical ADS-B questions


MCirrusSR22
22nd Mar 2024, 23:34
For modern jet airliner aircraft from 2010 to date can someone please let me know what of the following statements are true (1-5).

Technical questions.

If a combined mode S and ADS-B transponder has the transponder knob set on 'ALT OFF'.

1 - Assume for the MODE S signal the air traffic controller would see the aircraft identification but no altitude displayed on their radar screen.

2 - The ADS-B data recorded would show the aircraft's latitude/longitude but show no pressure altitude taken from the aircraft's altitude encoder and not show any GPS derived altitude.

3 - The ADS-B data recorded would show the aircraft's latitude/longitude but show no pressure altitude taken from the aircraft's altitude encoder BUT WOULD show the GPS derived altitude.

4 - The ADS-B data recorded would show the aircraft's latitude/longitude and also show the pressure altitude taken from the aircraft's altitude encoder and also the GPS derived altitude.

5 - The ADS-B data captured by all official ADS-B ground stations would always capture the following when the aircraft transponder is set for normal flight e.g. 'TA/RA' :

(a) The Aircraft's Latitude/Longitude.

(b) The Aircraft's Pressure altitude derived from the aircraft's altitude encoder.

(c) The Aircraft's GPS altitude derived from the onboard GPS receiver.

DaveReidUK
24th Mar 2024, 08:08
I don't think many aircraft send GPS altitude.