Hope we can get the Garmin guys to reply because I want to add another question.
1. Other than WASS and radio what do GTN 650 & 750's provide that the G3x touch can not?
Hello Jim,
We receive this question often, so it probably warrants some explanation. Every G3X and G3X Touch display contains an excellent non-certified WAAS GPS receiver, but that is only the first small step in achieving performance and functional parity with a certified IFR navigator like the GTN 6XX/7XX.
There is a fairly common misconception that if you have a WAAS GPS receiver, then you must have everything needed to fly IFR WAAS GPS approaches.
The two TSOs listed below specify the required performance and functions of a certified WAAS GPS navigation sensor (TSO-C145) and a complete stand-alone IFR navigator capable of being used for all phases of IFR operation including enroute, terminal, and approach (TSO-C146).
TSO-C145, AIRBORNE NAVIGATION SENSORS USING THE GLOBAL POSITIONING SYSTEM (GPS) AUGMENTED BY THE WIDE AREA AUGMENTATION SYSTEM (WAAS)
TSO C146, STAND-ALONE AIRBORNE NAVIGATION EQUIPMENT USING THE GLOBAL POSITIONING SYSTEM (GPS) AUGMENTED BY THE WIDE AREA AUGMENTATION SYSTEM (WAAS)
While the Airman's Information Manual may not be regulation, it is the FAA's guidance on using GPS for IFR operations.
2. IFR Use of GPS
(a) General Requirements. Authorization to conduct any GPS operation under IFR requires:
1) GPS navigation equipment used for IFR operations must be approved in accordance with the requirements specified in Technical Standard Order
(TSO) TSO−C129(), TSO−C196(), TSO−C145(), or TSO−C146().
It further specifies what is required to use GPS as the sole source of navigation (even enroute) if you are not using a WAAS corrected TSO-C146a navigator like the GTN.
2) Aircraft using un-augmented GPS (TSO-C129() or TSO-C196()) for navigation under IFR must be equipped with an alternate approved and operational means of navigation suitable for navigating the proposed route of flight.
Many reading this will quickly say "yes, but we fly EAB aircraft, so we don't need TSO'd equipment. We
only have to meet the performance requirements of the TSO'd equipment."
While this may be true, meeting the performance requirements for IFR operations to safely fly down to minimums (sometimes 200 ft) in the clouds on an LPV approach is a tall order.
DO-229 specifies the Minimum Operational Performance Standards (MOPS) for TSO-C146 navigators like the GTN 6XX/7XX. It is over 500 pages and contains very strict requirements on just about everything imaginable associated with IFR navigation using a WAAS GPS navigation source.
The performance requirements for integrity monitoring and alerting to make sure a pilot does not continue toward the earth on a precision approach when the integrity of the 3D navigation solution is not assured are particularly stringent.
We take IFR operation very seriously, and feel that the G3X integration with Garmin IFR naviagtors provides the best of both worlds. The affordability of a non-certified EFIS system with the design assurance, performance, and safety of a rule compliant certified IFR navigator.
Thanks,
Steve