Hey guys,

Been trying to sort out my understanding of the numbering requirements for my situation. If you guys can please give me a sanity check:

I currently have shitty vinyl tail number lettering on my tail, which is not 12" tall, and also extends onto the rudder which seems common but according to what I understand of the regs - it's not supposed to.

That said, I desire to downsize to 3" lettering, and justifying it because the plane is a 1979, and I understand that pre-81 that's ok. Right?

There's a likely scenario where I need to fly my 206 into South America on business this summer. From what I can tell, there are two concerns with this: crossing the ADIZ, and ICAO number requirements.

From what I can tell, 12" lettering is required for crossing the ADIZ, seems that is usually understood as on the tail or empennage, and can be temporary if need be.

ICAO requires 12" numbering, which can be under the left wing.

Has anyone ever found that the ICAO numbering suffices for the ADIZ? IE: can I install the 3" tail numbers on the tail, but add 12" numbers under the left wing and be kosher for both the ADIZ and staying in the good graces of South American requirements?

My understanding is that 12” numbers on the fuselage or tail satisfy both FAA and ICAO for the southern ADIZ. FAA states they may be temporary.
This document should get you started, the part about the numbers is towards the end.

https://www.faa.gov/air_traffic/publica ... e/#reg_num

Otherwise, your numbers can be 2” (vs 3”), that’s for aircraft built at least 30 years ago(vs a specific year). Paragraph b in this document:

https://drs.faa.gov/browse/excelExterna ... pened=true

Have a great trip!

US to Canada is not crossing ADIZ. Check out your sectional for ADIZ. Smaller N numbers OK.

I made a post years ago after quite a bit of research ... I even received bad information from AOPA so I decided to document what I found. Note this is from 2012 so there may have been some changes but I'm not aware of any.

click the link then scroll up to read my long post

https://backcountrypilot.org/forum/n-number-sizing-9646?p=126257&hilit=n%20number#p126257

48Stinson1083 wrote:US to Canada is not crossing ADIZ. Check out your sectional for ADIZ. Smaller N numbers OK.

I didn't realize Canada was between the US and South America?