Loc & Gs Deviation

[GAMEOVER]

Hi Everybody,

I´m not sure about the requirements during a stabilized approach regarding LOC and GS in the following ILSs

What is the maximum deviation allowed for LOC and GS please.?

1. ILS CAT I
2. ILS CAT II
2. ILS CAT III

Thanks in advance.

[Capn Bloggs]

It should be in your ops manual.

Ours is ½ scale maximum for both LLZ and GS (Cat 1).

Otherwise, it's game over!

[NZScion]

As Capn Bloggs said, half scale deflection is the maximum. The indications also need to be stable (i.e. no going from half scale too high, to half scale too low, all the way down the GP). If you are unable, its time to get some missed approach practice

[GAMEOVER]

Hi ALL

Thanks for your answeres, but..

According to Airbus (Flight Operations Briefing Notes) The maximum, flying stabilized approaches are:

LOC: 1/4 dot
GS: 1 dot

Airbus doesn´t say anything at all about CAT I, II, or III

They are ambiguous, I would be very grateful if someone could tell me the requirements (LOC&GS) in his/her Company in the following:

CAT I
CAT I
CAT III A

I´m aware that flying CAT III-A having GS 1 Dot deviation OR "half scale..." then you have to carry out a missed approach.

I don´t understand those notes from Airbus.

[Intruder]

Ours (747) are 1/2 dot G/S and 1/3 dot LOC.

[Capn Bloggs]

Probably confusing the issue is the definition of a "dot". As displays are different, perhaps we should be relating description of limits to the scale range eg ½ scale.

[sevenstrokeroll]

for our whole fleet...just like intruders!

737, A319,20,21, 757 767 A 330 etc.

in prehistoric times we use to say...everything had to be in the donut

old timers?

[Capn Bloggs]

1/3 dot LOC.

What is 1/3 of a dot in relation to full-scale?

Are these the dots (this isn't an expanded scale):

[Intruder]

AFAIK, a dot is standardized by the FAA and/or ICAO (though I don't know the standards/definitions). On a normal display, a dot is a dot, and 2 dots are displayed either side of center for both LOC and G/S. On the 744, the dots are replaced by rectangles on the LOC expanded display, and each rectangle is half a dot (i.e., the display is 4x as sensitive). The 1/3 dot is defined by the diamond cursor first touching a rectangle.