MINS knob (Radio and Baro)

[speedbird109 0]

Hi,

 

I wanted clarity o how to use the MINS knob with the two options Radio and Baro.

 

1) Assume that I am landing at VIDP Delhi whose runway 10 is 719 msl. If I am executing an ILS landing, do I set the Radio as 919 OR do I set the Baro as 200?

How does this work

 

2) Does one use the MINS only during landings exclusively? OR can we also use it as a reference on high terrian airports too?

 

Thanks

Sanjay Dhareshwar

[rsvit 16]

1) Assume that I am landing at VIDP Delhi whose runway 10 is 719 msl. If I am executing an ILS landing, do I set the Radio as 919 OR do I set the Baro as 200?

How does this work

 

If it's ILS CAT I or non-precision approach (not sure about RNAV(RNP)), then you have to set up BAROmetric DA/MDA. Here correct setting would be 919' BARO, because I see DH here would be 200, it's usual for CAT I.

 

On CATII/CATIII you set up radio altimeter DH, so position the selector to RADIO.

 

 

To clear this up. DH/MDH is determined with radio altimeter that shows actual airplane height above the ground.

DA = threshold elevation+DH. So, if you are using QNH, then you will use barometric altimeter for DA/MDA, that shows altitude above MSL.

You can read several paragraphs in FCTM, section Approach and missed approach.

 

2) Does one use the MINS only during landings exclusively? OR can we also use it as a reference on high terrian airports too?

It's useful to set engine out acceleration altitude here.

[scandinavian13 5,192]

Where is this "if it's x category, you use y; if it's q, you use r" coming from? In my last check of the regs I've found no such language.

 

My understanding is if both (radio- and baro-based mins) are published, you may use either. If only one is published, you must use that.

[wisefox7524 9]

Radio mins are typically used for CATII/III approaches. Baro mins are used for everything else - CAT I, RNAV (GPS/RNP) VOR, LDA, Visuals, etc.

[scandinavian13 5,192]

"Typically"

 

When people explain it, though, they tend to map it out with "CAT I uses BARO, and CAT II and beyond uses RADIO," never explaining that it's not a requirement.

[rsvit 16]

Yeap, it's not a rule, but as far as I know exceptions are rare.

Non-precisions not require flat area near runway and RA figures may be non-reliable. And sometimes on CAT II/III you can find words "RA not authorized".

 

I'll take into account your notice. It was just my simple simmer's opinion, airmen still correcting my omissions. It would be nice to read some regs, of course if I can access them.

Edited July 27, 2012 by rsvit

[scandinavian13 5,192]

Non-precisions not require flat area near runway and RA figures may be non-reliable. And sometimes on CAT II/III you can find words "RA not authorized".

 

Right. Earlier, I'd thought to say "if they had RADIO min published, I'd use that over BARO anyday because it's more accurate," but then I remembered variations in ground level, and ground clutter could make it less so. I was just trying to make sure people don't think it's a requirement. I don't like sim-isms.

 

The FAA regs can be found here, btw:

http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&tpl=/ecfrbrowse/Title14/14tab_02.tpl

[Daveng3 0]

From FCTM for those who not seen it.

 

A Decision Altitude or Height is a specified altitude or height in an ILS, GLS, PAR, or some approaches using a VNAV path or IAN where a missed approach must be initiated if the required visual reference to continue the approach has not been established.

 

The "Altitude" value is typically measured by a barometric altimeter and is the determining factor for minima for Category I approaches, (e.g., ILS, GLS, or RNAV with VNAV). The "Height" value specified in parenthesis, typically a RA height above the touchdown zone (HAT), is advisory. The RA may not reflect actual height above terrain.

 

For most Category II and Category III fail passive approaches, the Decision Height is the controlling minima and the altitude value specified is advisory. A Decision Height is usually based on a specified radio altitude above the terrain on the final approach or touchdown zone.

 

Pretty straight forward to me and in line with my experience, only to be adjusted by the airport approach plate as the example from rsvit.

[scandinavian13 5,192]

Again...

 

"Typical," and "typically" are not regulatory in nature.

 

Take a look here:

http://155.178.201.160/d-tpp/1208/05100IL1R.PDF

 

It lists 512/18 200

 

The 512 is the MDA, whereas the 200 is the DH. Is there any reg preventing me from using 200 on the radio?

[FirstOfficera320 1]

Hi guys,

 

I know it's Airbus, but I would assume Boeing is the same. (Finally it's up to the operator and the state of the AOC)

 

"Minima (DH for CAT II or CAT III approache and MDA for others approaches"

 

Also to be noted that when using DH it's much more accurate and it's also temperature corrected. MDA is not.

 

Regards,

[speedbird109 0]

• It's clear now. Thanx All.
  

[Daveng3 0]

The 512 is the MDA, whereas the 200 is the DH. Is there any reg preventing me from using 200 on the radio?

 

When on the gideslope you only descend through MDA once, how many times could you descend through DH 200 and when do you call decision the 1st, 2nd or 3rd occasion.

 

I realise you are requesting for a set of regulations for hard difinitive answers and for all I know there may well be but the previous postings are pointing out an Internationally accepted convention since the conception of Autoland for DH being used.

[scandinavian13 5,192]

I realise you are requesting for a set of regulations for hard difinitive answers and for all I know there may well be but the previous postings are pointing out an Internationally accepted convention since the conception of Autoland for DH being used.

 

Right. I'm not trying to be a jerk about it. My problem is that a lot of misinformation spreads through aviation because people phrase things as if they're mandatory by reg when it's only company SOP, and so on. I'm not saying the convention doesn't make sense. I'm saying it should be phrased as if it's a convention when explaining it. That's all.

[Sekstifire 10]

Personally I never use DH unless I'm autolanding (which I havent done in over two years)

[Olmo 0]

The 512 is the MDA, whereas the 200 is the DH. Is there any reg preventing me from using 200 on the radio?

ICAO Doc 8168 talking about how to determine DA/DH:"OCA/H values are based on the standard conditions [..] that follow [..] ILS: a ) Category I flown with pressure altimeter; b ) Category II flown with radio altimeter and flight director;".

 

The RA wouldn't simply allow you to define your position 200ft above the runway threshold. All the heights (MDH/DH) are based on threshold elevation (aerodrome elevation when applicable) and not on what lies direclty below the aircraft. For the same reason charts depicting a Cat. II approach will provide the usual DA/H plus the RA.

 

Regards,

 

Olmo DI CARLO