FMC's not approved for GPS/NPA's

[olderairhead]

It was brought to my attention yesterday that in Australia, FMC's are not approved for GPS/NPA's. This was news to me (maybe I don't read the regs enough) so I thought I would pass it on as it may impact on a number of operations.

The following is an extract from CAAP 178-1(0) released in October.

2.7 CAN I FLY AN RNAV APPROACH?
At present the only Area Navigation (RNAV) instrument approach procedures available in Australia are GPS/NPAs. Although many aircraft fitted with modern Flight Management Computer (FMC) systems incorporate the capability to fly approach procedures based on GPS or ground-based aids, at present no FMC is approved in Australia for this purpose. If an FMC is used to assist in flying an approach, it is necessary for the navigation system upon which the procedure is based to be monitored (NDB, VOR, etc) to ensure that the obstacle clearance requirements of the approach are met, and that the procedure is flown within the tolerances of that navigation system.

The CAAP can be accessed from here (http://www.casa.gov.au/rules/caap.htm) or downloaded from here (http://www.casa.gov.au/download/CAAPs/ops/178-1.pdf)

[Feather #3]

Watch this space.

G'day ;)

[Captain Stoobing]

Is there a difference between an FMC and an FMS? The a/c I fly has an FMS that receives it position from its internal GPS, VOR's, DME's and an air data computer. I understand that conducting a GPS/NPA is OK once you are checked out.

Capt Stoobing :D

[Capn Bloggs]

The FMC/S in the Avro RJ is approved for GPS NPAs, and they are done in anger. It is designed to ignore all other navigation system inputs IF it has a suitable GPS position solution (it even ignores the IRSs). Perhaps this is the subtle difference with older/other FMCc/s. The other navaids ie IRS, VOR-DME or DD cannot be isolated and therefore those FMSs are not allowed to be used for primary guidance on GPS NPAs because they will pollute the GPS position.

Stoob, the definition of an FMS or FMC is indeed nebulous. Dick would probably call his Trimble an FMS, but in reality what is the definition?? Is a box only a true FMS when it provides a couple-able VNAV solution? Or does it make the grade if it only has all the manufacturers performance data in it but without VNAV?

[TAY 611]

On the Gulfstream 4 we can fly any approach (VOR, NDB, GPS) that is coded in the database using the FMS. However when flying a RNP .03 RNAV approach the FMS must be using GPS only navigation mode.
FMS--FMC no difference except just a manufacturers terminology.

[4dogs]

Folks,

I think the CAAP reference is to "magenta line"overlay approaches such as those to which Tay 611 refers:

"On the Gulfstream 4 we can fly any approach (VOR, NDB, GPS) that is coded in the database using the FMS."

In Oz, you are not authorised to use that FMS facility and there is no overlay design standard. In short, you fly a GPSNPA using the FMS if your AFM includes the required airworthiness approval and you fly VOR and NDB approaches by reference to the basic instrument display.

The CAAP, which is very good, is about all forms of NPAs rather than the most common usage of the term, GPSNPA.

Stay Alive,

[Grivation]

CASA currently will not permit operators of the 737-NG (yes it is fitted with dual GPS's!) to conduct NPA approaches. The reason given is that there is no ability to alert the crew when RAIM is lost. There is of course the constantly displayed RNP performance and alerting functions for being outside the RNP tolerance but this isn't acceptable to our CASA!

The idiotic thing about this whole ongoing argument is that screwing a Garmin 155 (or similar) to the top of the glareshield would be acceptable to CASA and we could then carry out as many NPA's as needed!!!!

[halas]

So the 777 has most of the GPS approaches around the world in the data base, with the same RNP alert as the what was mentioned in the above posts on the 737, but due to no RAIM lost alert function the only FIR that l can't use it in is Australias.

Fair Dinkum:confused: !!??

l think the ADIRU is more switched on than CASA with or without RAIM!

halas

[On eyre]

The perils of all that technology!!

Out in the bush with a Garmin 155 in the light twin the GPS NPA's are a dream and extremely useful - plenty of airfields with the plates now too!! Way to go.

[ozoilfield]

Can anyone explain why a FMS must intergrate engine and performance parameters with vertical and horizontal nav information in the interpreation of an FMS in CAO 40.2.1 ss 2.1. (Page 3 of the CAO)

CASA have not been able to come up with an answer to thos question in over 2 years.

[slamer]

If covered above, then ignore the following......

FMC/FMC's,(The Brains of the FMS), use's flight crew-entered flight plan data, airplane systems data and data from the Nav data-base to calculate a/c present position and GENERATE the pitch, roll, and thrust commands necessary to fly an optimum flight profile
(where you are at)

FMS, then uses this information to calculate commands for manual and automatic flight path control, depending on phase of flight.
(where you are going)
In addition (in some systems) the FMS tunes Nav radios for auto position updating.

So... one is the Brains and the other is the system (or part of it) to facilitate those Brains

Maybe a little Nebulous, the key is in comprehension, guess thats why we have Lawyers eh!!!

Maybe some Genius can come up with the Boeing definition?