Phenom 300 & GPS

[atakacs]

Direct from this FAA NOTAM (https://www.faasafety.gov/files/notices/2016/Jun/CHLK_16-08_GPS_Flight_Advisory.pdf):

ADDITIONALLY, DUE TO GPS INTERFERENCE IMPACTS POTENTIALLY AFFECTING EMBRAER PHENOM 300 AIRCRAFT FLIGHT STABILITY CONTROLS, FAA RECOMMENDS EMB PHENOM PILOTS AVOID THE ABOVE TESTING AREA AND CLOSELY MONITOR FLIGHT CONTROL SYSTEMS DUE TO POTENTIAL LOSS OF GPS SIGNAL.

What is so specific to the Phenom 300 when it comes to flight control & GPS ?!

[Superpilot]

Intrigued I was too and just discovered the following:

A lot of the new Gx000 kit uses Garmin’s GRS 77 Attitude and Heading Reference System (AHRS). Combining inputs from GPS, magnetometer and air data computer, the Garmin AHRS provides an accurate digital referencing of your aircraft’s dynamic orientation in space. Also, unlike some competitive attitude/heading sensors, it’s even able to restart and properly realign itself while the aircraft is moving.

[atakacs]

I would hope that there is a way to turn off the GPS feed and still have the AHRS deliver reliable indications ? Not to mention complementing GPS with GLONASS and Galileo signal...

As much as GPS is a huge boon to the industry I wouldn't fly any aircraft depending solely on it !

[alldaysushi]

Atakacs,

I've had this situation occur with loss of GPS, specifically over White Sands New Mexico, USA. We were out of GPS signal for 200 miles. Fortunately only adjustment was to inform ATC, maintain a heading mode, and back up with VOR, if one happens to be along route.

Super pilot: Automatic realignment does occur, and return to NAV mode was uneventful. No flight control abnormality in this specific example.

Safe journies...Sushi

[A-FLOOR]

This briefing explains how GPS loss currently affects the Phenom 300:

http://www.faa.gov/documentLibrary/media/Notice/GENOT_7110_711_EMB-300.pdf

[atakacs]

Thanks for the tech briefing - not too reassuring to be honest...

[underfire]

I bet the RAIM check is right at the top of the checklist!

[khorton]

I'll take this design over the earlier Collins AHRS, which only used pitot-static inputs to help stabilize the AHRS attitude. There have been more than one event of pitot icing on CRJs leading to significant errors in the attitude outputs from the AHRS, and loss of all air data output to PFDs. Having the L PFD, R PFD and the standby all showing significantly different attitudes, with no valid airspeed info and altitude info displayed only on the standby is not a great situation to deal with.

[atakacs]

I'll take this design over the earlier Collins AHRS, which only used pitot-static inputs to help stabilize the AHRS attitude. There have been more than one event of pitot icing on CRJs leading to significant errors in the attitude outputs from the AHRS, and loss of all air data output to PFDs. Having the L PFD, R PFD and the standby all showing significantly different attitudes, with no valid airspeed info and altitude info displayed only on the standby is not a great situation to deal with.

I can see your point.

I wonder if there is a way to design any critical system depending on GPS in such a way that it is able to detect loss of signal accuracy?