What does mean AYF?

[Бурундук]

Please, explain what does mean AYF in the sentence (about Gloster Javelin):

"In addition with A.I. equipment Gee, A.Y.F., I.L.S. and I.F.F. were fitted".

Can't find this abbreviation.

Thank you in advance,

[Техник]

I guess its fingertip mistake.
Most likely they meant ADF.

[Lukas]

In addition with A.I. equipment Gee, A.Y.F., I.L.S. and I.F.F. were fitted
http://www.technoff.ru/ARDO-AYF-220.htm ??? :) :) :)

[xolodenko]

Looks like they really meant AYF when they said it:

http://www.btinternet.com/~javelin/p08_technical_notes/p08_technical_notes.htm

[Mechanic]

It's a radio altimeter, and the designation seems to be just a letter code, not an abbreviation. See http://www.fernblatt.net/m6.html

[Mechanic]

http://hereford.ampr.org/millist/m11.html
Still missing what you want exactly. These letters are a part of some code that was in effect before the JETDS. Probably British. Find the code and you're done.

[Бурундук]

Mechanic, thank you for the interesting link. Yes, it seems it just letter code...