MNPS airspace A340

[BITE System]

To enter MNPS airspace you require 2 LRNS

If you lose 2 IRU's you would still have 2 FMs, 3 MCDUs and 1 IRU left

If your aircraft also has 2 GPS, would you not still have 2 LRNS as a GPS is counted as a LRNS? ie: 1st LRNS = 1FM/MCDU and 1 IRU. 2nd LRNS 1 FM/MCDU and 1 GPS

[411A]

If your aircraft also has 2 GPS, would you not still have 2 LRNS as a GPS is counted as a LRNS?
The short answer is yes, dual GPS approved....and has been since 1998, with Air Atlanta operating L1011 aircraft transAtlantic, at that time.
Been there, done that, personally....long ago.

[Mansfield]

A good reference for these questions is the North Atlantic MNPSA Operations Manual, which can be downloaded at this link:

http://www.nat-pco.org/nat/MNPSA/MNPSA_2008.pdf

Take a look at paragraph 1.3.2, Lateral Navigation. Note that each navigation system must either be an INS, a GPSS, or have input from at least two IRUs or other MNPS equivalent sensor systems. So your scenario with one IRU supplying one FM might not be acceptable.

Note also the requirements for GPS approval, as well as the requirement that each system provide continuous indication of aircraft position relative to track.

Some of these points may help in determining whether your configuration could be approved.

[Neupielot]

Hi. Got a question regarding LRNS requirement. It says 2 LRNS (for my ac type-A320) are needed for oceanic ops/remote areas. How do i know if the route is considered remote? Sorry if this sounds silly.....Thank you.

[CanadaRocks]

The GPS is not used for nav but only updating FM/IRS position.

[streetcar driver]

If I lost 2 IRUs I would not even think about entering the MSPS airspace. The IRUs are needed for much more than navigation.