No AR for the ATR?

[belowMDA]

I was just wondering whether the Mt Cook ATR 72-600 is likely to be RNP-AR capable in the near future? I had the impression it was available out of the box, however that doesn't seem to be the case.

[c100driver]

The 600 was advertised as AR "capable" but until Mount Cook ordered them no one has specified the capability.

As a result ATR is having to do a lot of work to actually certify it.

[Sqwark2000]

Mount Cook is currently developing its AR capability. I think we're the 1st operator to attempt it.

I think there was some clever marketing material which cleverly blurred the lines between "is" AR capable and "can be" AR capable 😉

[belowMDA]

So the aircraft is still not certified for AR? Suppose approaches in anger are probably a couple of years away then...

[mattyj]

The issue won't be the aircraft, the airline, the training or the manuals, the issue will be caanz. The factory can issue you with AFM and POM that states your system can achieve +/- 0.1 Nm at all times and has terminal scaling and is suitable for all RNP types factory standard, but unless the Wellington handbrake brigade are satisfied for themselves (including the vast caa 24091/08 application form) and issue you with the appropriate 2129 radio station approvals, you can hurry up and wait like the rest of us!!!

[VC9]

Try CASA Australia for belligerent incompetence. They are the masters of the world for that kind of action.

[ZFT]

Won't the aircraft need the FMS Standard 2 upgrades to be accomplished first? My limited understanding was only aircraft delivered after 12/14 were at the required standard.

[c100driver]

Actually Matt in this case it is not the CAA that is the problem. I have heard that the main problem is with the coasting after GNSS failure due to the aircraft not having IRS position information.

In a RADAR environment you could use DR initially then vectors. But in ZQN with the loss of the GNSS position information in the valley you are up the creak without a paddle.

The Bus and the B737 have about 4 minutes before the IRS Nav Only performance exceeds the RNP, more than enough time to extract from the valley to MSA.

[underfire]

Pretty certain that on A and B, the IRS drift to RNP is a bit more than 4 mins, perhaps with 0.1, but certainly not 0.3....

Lets use 15

[empacher48]

Actually Matt in this case it is not the CAA that is the problem. I have heard that the main problem is with the coasting after GNSS failure due to the aircraft not having IRS position information.

In a RADAR environment you could use DR initially then vectors. But in ZQN with the loss of the GNSS position information in the valley you are up the creak without a paddle.


Yes, you do need an INS and ATR have got an INS which replaces an AHRS unit to provide that coasting ability.

It is what ATR are testing for approval at the moment. The new -600 sim in Auckland will have the ability to start AR training very soon.

[c100driver]

The ANP uncertainty (for want of a better term) grows mathematically not actually. It has been a long time since I did some work on this so my numbers could be out. On the B737 CL the loss of all GPS updating (our regulations require DME/DME and VOR/DME updating turn off for RNP AR approaches) causes the ANP to start expanding after 12 second coasting and then by .01 every 6 seconds.

Note that it is not a real ANP increase but mathematical "certification" ANP increase, the IRS system performs much better than that in reality.