TSO-C129a Alternate Requirements

[8 8ths]

Hello all, just after some guidance regarding the need for an alternate when utilising dual TSO C129a GNSS in RPT and charter operations.

My understanding previously was that a C129a unit could not be utilised for the purpose of meeting the radio navigation aid requirements for alternate planning at either the destination nor the alternate, however this appears to have been changed (perhaps quite sometime ago without my realising).

CAO 20.91 Appendix 13 (page 95 of 95) states:
6.6 For the purposes of flight planning, any required alternate aerodrome must have an available instrument approach procedure that meets the requirements of this Appendix for the equipment installed in the aircraft.
6.7 For aircraft equipped with (E)TSO-C129 ( ) GNSS systems, the alternate
aerodrome must have a non-GNSS approach procedure available and the aircraft must have the requisite equipment installed and operative.The AIP and Jeppesen mention extracts from CAO 20.91 regarding this as well (AIP ENR 3.3 para 2 / Jepp (electronic) Pacific - page 371 para 6).

Additionally the AIP and Jeppesen state under "Radio Navigation Systems" (AIP GEN 1.5 para 2 / Jepp Pacific - page 790 para 5.12):
If GNSS equipment in accordance with (E)TSO-C129 is used and if an alternate aerodrome must be planned:
a. navigation to the alternate aerodrome should be accomplished by use of ground-based navigation aids;
and
b. the alternate aerodrome should have a suitable approach that uses groundbased navigation aids, or the alternate aerodrome must be suitable for approach in VMC.So my questions are as follows:
1. If the aircraft is fitted with 2 x TSO-C129 GNSS units, provided that all other non nav-aid conditions are met regarding alternate planning, does the destination not require an alternate?
2. If the destination requires an alternate due to conditions not relating to nav-aids, does the nominated alternate require ground based nav-aid(s)?

I apologise for the long post and if it seems like I have answered my own questions, however I am just after clarification and guidance.

[KRviator]

I thought the reason for requiring a ground-based navaid at the alternate was due to the C-129 units not being compliant with FDE provisions, whereas a C145/C146 unit has the ability to detect faulty SV's and exclude them from the navigation equation to provide a valid position.

Just because you have two C129 units means diddly if they both come up with an incorrect position due to a dodgy satellite. But I'd like to know the chances of such an incorrect broadcast from a satellite actually occurring long enough to be a problem before the USAF pulls the plug on it.

[zanthrus]

Now that we have less than half of the ground based navaids thanks to the "intelligence" of Airservices Australia, good luck with that for c129 units!

[Vag277]

Zanthrus

The ground based aids have been decommissioned because the large jets are not equipped with ADF any more - INS and GNSS have replaced them and VOR are of limited enroute use to them or ATC. Therefore they were not prepared to pay for replacement and maintenance and the operators of older IFR aircraft were not prepared to pay for replacement and maintenance. QED

[Lead Balloon]

Yeah zanthrus. All that income tax, GST, and excise you pay on your aircraft's fuel is to make a bloated bureaucracy and monopolies rich. If you want to actually use something, you have to pay for that as well.

[gerry111]

Yeah zanthrus. All that income tax, GST, and excise you pay on your aircraft's fuel is to make a bloated bureaucracy and monopolies rich. If you want to actually use something, you have to pay for that as well.

Sydney's rapidly becoming the automotive equivalent. Soon to become the toll road capital, not only of Australia but the world. :ugh:

[Lead Balloon]

GIII, you should get along to see Dr Cameron Murray, who wrote Game of Mates, at the Crows Nest Hotel 6 - 8pm on Tuesday July 18. This is an interesting listen, too, and specifically mentions Sydney road arrangements: » Australians fleeced by business insiders | Sydney Talk Radio (http://www.2gb.com/podcast/australians-fleeced-by-business-insiders/)