Hi everyone

 

When performing an ils, one gets the descision heights off the airport charts. the number is usually bold (for eg ils 26L EGKK is 400) followed by a number in brackets (200). i have worked this out to be the descision height in MSL (bold) and AGL (in brackets) - but which number do i enter onto the BARO settings on the instrument panel?

 

Thanks

 

Rory

The number you enter onto the BARO settings will always be the DA or MDA. The DH or MDH are radio altitudes.

this is the table for the ILS 26L, you can see there's category II and I, there's specific which contain III also. let's look at catI, there's A,B,C,D, usually we are C (different landing speeds, that all that matters) you cann see the minimum is 356 which is acutally 160 above the ground, that's the height whether you continue to approach, or stoping for some reason. hope it helped.

i have worked this out to be the descision height in MSL (bold) and AGL (in brackets) - but which number do i enter onto the BARO settings on the instrument panel?

 

Just in case you can't infer it from the above:

MSL is BARO

AGL is RADIO

I don't know why, but when I first started learning charts this confused me more than anything. Numberz is hard.

As I understood it:

 

-For every approch including ILS CAT I you enter decision altitude

-For ILS CAT II and CAT III you enter decision height

 

Thats, how I understood it, which doesn't mean that it is correct, so if it is wrong please go ahead and correct me.

this is the table for the ILS 26L, you can see there's category II and I, there's specific which contain III also. let's look at catI, there's A,B,C,D, usually we are C (different landing speeds, that all that matters) you cann see the minimum is 356 which is acutally 160 above the ground, that's the height whether you continue to approach, or stoping for some reason. hope it helped.

 

Careful with the NATS charts, they give OCA(H) (obstacle clearance altitudes (heights)), not mins. A CATI ILS decision hight can't be lower than 200ft.

 

As I understood it:

 

-For every approch including ILS CAT I you enter decision altitude

-For ILS CAT II and CAT III you enter decision height

 

Thats, how I understood it, which doesn't mean that it is correct, so if it is wrong please go ahead and correct me.

 

That's right. CATI decision alt using baro mins, CATII/III using decision height using radio mins.

 

This thread will give you more info if you wish to learn more: http://forum.avsim.n...1555-cat-iiiii/

Pretty much.

 

Unless you see RA (radio altimeter) right before the number value, you should be using BARO.

Example

Problem is, everybody is using different charts and it is a mess to orientate oneself in. If only LIDOs were everywhere. Oh well, I can wish.

 

example LIDO.

 

 

 

big, bold number you input (BARO). Small number saying how high it is above runway level, also visibility (slight OT, one of simisms I notice is that visibility minimums are disregarded, only vertical minimums are considered). Clearly states RA when you need to use Radio Altitude.

Clearly states RA when you need to use Radio Altitude.

 

NACO does as well.

It does, but there is NACO, jepps, LIDO, Navtech, UKCAA and then many other EU national formats.... you never know what kind of chart will someone pull up.

PMDG-NGX-FCTM 5.7-5.8 Landing Minima (pp 183-184) - has a clear & concise explanation MDA, DA & DH & when to apply them...indeed the whole chapter...indeed the whole document is a goldmine of info where many common Qs have answers laid out in a clear, concise & sensible format...this is the same format for all Boeing FCTMs.

 

Oh dear!...did I just refer to the manuals that came with the product?

 

Shame on me.

Pretty much.

 

Unless you see RA (radio altimeter) right before the number value, you should be using BARO.

Example

 

In this example what does RA 96/12 100 mean, the DA being 386?

I stand to be corrected as I don't normally use FAA style chartage but.....

 

"S-ILS 1C" ..... Or a straight in ILS to RWY 01C ...& in bold below....a Category II ILS procedure requiring the flight crew to be legally certified & aircraft to be correctly equipped & legally certified to fly the approach.

 

RA 96/12 - This is the Radar Altimeter Setting Height or Decision Height (DH) of 96 feet set against the Radio Altimeter with a corresponding Runway Visual Range (RVR) of 1200 feet.

 

100 - is the HAT or the Height Above Touchdown (in feet) measured against the SERVO Altimeter which (set to the local QNH)...in this case this corresponds to a barometric height of 386 feet Above Mean Sea Level (AMSL)...supplied for info & cross reference only:

 

HAT (100 feet) + TDZE (Touchdown Zone Elevation - 286 feet AMSL) = 386 feet AMSL

 

Now I am feeling 'foggy'!

HAT (100 feet) + TDZE (Touchdown Zone Elevation - 286 feet AMSL) = 386 feet AMSL

 

'zzactly.