ILS glide slope
 

Can anyone help me. I am trying to find out if there is a rule regarding missed approaches if greater than one dot high or low. I have been told (but un able to verify) that if an A/C is greater than one dot high or low on GS it must carry out a missed.
Does any one know?

The usual rule is half-scale deflection. On some displays this is one dot, on others it is 2½ dots. I think it comes from PANS OPS safety limits - full scale deflection is 0.75° high/low.

Orion 1 as my friend says it really depends on the display you are using.On light a/c with an OBI/CDI these tend to be 5 dot displays where half scale deflection is 2 1/2 dots.IR test limits are half scale deflection.On most EFIS equipment is 2 dot.
Rule is "MORE THAN HALF SCALE DEFLECTION-THROW AWAY THE APPROACH"

cheers AUTOTHROTTLE

In the US, at least, the limits are set by your carrier's procedures. A "stabilized approach" is mandated by the FAA.

We use 1 dot deflection below 1000 if IMC, and 1 dot below 500 if VMC.

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