What's an 'L-route' and 'M-Route'?

[JimNtexas]

I was looking at the enroute charts for the New Orleans area and I notice that there are 'L-routes' and 'M-routes' going south towards Mexico.

Specifically out of the Leeville VOR, L214. Near it is an 'A-route', which is defined in the Aeronautical Chart User's guide as 'LF/MF airway' even though it has GPS waypoints on it.

There is also L208 out of Sabine Pass (SBI) VOR and M345-575 out of Tibby (TBD) VOR.

Are these Mexican route names? They aren't defined in the L-21 chart legend nor the User's Guide that I can find.

 

[gsengle]

I believe these are old ndb airways


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[midlifeflyer]

I believe these are old ndb airways


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I don't think so. You can see from the solid black line they are VOR based. Black for VOR, brown for L/MF, blue for RNAV.

They are international routes. You can see something similar on the east coast, where you have routes like BR55V. In that case, it "Bahama Route" and an A in front is an oceanic route. I don't know what the L and the M specifically stand for.

 

[Acrodustertoo]

Azblackbird will be here shortly to tell us, he has been furiously reading the far/aim.

Now just sit back and have a Dr. Pepper and a Diablo sandwich.