What is the deal with PARs?

[BACONATOR]

Whiting Field's Radar Instrument Approach Minimums (attached below) disagree. I don't see DA at all, just DH and HAT...


Check your DOD approach plates. What you are arguing as DH is HAT.


Maybe you should follow your own advice. DA is an ICAO term, unless the FAR/AIM forgot to consult you before defining it. When you're shooting a PAR into South Whiting Field, CANADA... THEN you can tell me you were at DA. That link is straight from the pilot controller glossary, rather than some guy's VIRTUAL AIRLINE SITE!

I was reading the hard-copy of the PCG myself. I also read DH/A within the AIM portions about missed approach procedures, and the definitions at the beginning of the FARs.

Splitting hairs or not, sometimes the little things make a difference to me. I prefer DA because I fly approaches on altitudes (MSL), not heights (AGL). It just makes sense to me. If I'm wrong, so be it. But I think if it's in the FAR/AIM, it's good enough for me.

Same way guys talk about vibrations being "dampened", it's inaccurate. Vibrations aren't made moist, they are "damped". Just because a word or phrase is used commonly doesn't mean it's correct.

 

[insanebikerboy]

And don't tell me you use your RADALT for approaches and go missed at DH. Not all aircraft (as in... non-helo) have Radalts...

Actually, it's good headwork to use your radalt when doing a PAR. Set the raws bug for the HAT (since that's AGL) and you have another reference for when you hit the DH. It's another instrument in the cockpit that will back you up so use it.

 

[BACONATOR]

Actually, it's good headwork to use your radalt when doing a PAR. Set the raws bug for the HAT (since that's AGL) and you have another reference for when you hit the DH. It's another instrument in the cockpit that will back you up so use it.

I usually set my DH bug 50-100ft above the DH (as... in actual height... HAT), as a backup sanity check to bring me back to altitude as I approach my DA. I DON'T use it as an absolute indicator of my MAP since height AGL can change drastically even on short final (Ever been to Sedona?).

Another common mistake I've seen a lot of people make is understanding that HAT = straight in approach, HAA = circling approach. For whatever reason, a lot of people seem to think it has to do with precision/non-precision.

Phrog: I guess my main issue is that when people use the term "DH" without really thinking about what they are saying, it's inaccurate. A "height" is AGL. But what is "DH" on that approach plate for the PAR? It's an MSL altitude.

 

[phrogpilot73]

Splitting hairs or not, sometimes the little things make a difference to me. I prefer DA because I fly approaches on altitudes (MSL), not heights (AGL). It just makes sense to me. If I'm wrong, so be it. But I think if it's in the FAR/AIM, it's good enough for me.

Little things do make a difference. The only reason I pitched a bitch is because I just finished re-writing the squadron's instrument exam. When you compare all of the information presented before you (FAR/AIM/PCG/Approach Plates, and I'd venture GP) it is clear that DH is a term associated with the US, and DA is a term associated with ICAO. Outdated or not, dem's the facts. You may prefer it - but if all the aviators in this country are using one term, and you're using another...

 

[insanebikerboy]

I usually set my DH bug 50-100ft above the DH (as... in actual height... HAT), as a backup sanity check to bring me back to altitude as I approach my DA. I DON'T use it as an absolute indicator of my MAP since height AGL can change drastically even on short final (Ever been to Sedona?).

If you're up for splitting hairs, using your reference of Sedona isn't accurate since 1) there isn't a PAR there, and 2) the HAT for any approach is in AGL, which is what the radalt gives. So, regardless of it being 100 feet or 1000 feet agl, you could still set your radalt for it and you have a second reference for your DH.

Your technique of setting it 50-100 feet higher is one I've heard guys use too, and it's just as effective. My point was that if you have another instrument in the cockpit you might as well use it.

 

[Pags]

Little things do make a difference. The only reason I pitched a bitch is because I just finished re-writing the squadron's instrument exam. When you compare all of the information presented before you (FAR/AIM/PCG/Approach Plates, and I'd venture GP) it is clear that DH is a term associated with the US, and DA is a term associated with ICAO. Outdated or not, dem's the facts. You may prefer it - but if all the aviators in this country are using one term, and you're using another...

Since he's flying a USN helo with a USN instrument qual and using DOD plates, I'd think DH would be the way to go.

 

[BACONATOR]

If you're up for splitting hairs, using your reference of Sedona isn't accurate since 1) there isn't a PAR there, and 2) the HAT for any approach is in AGL, which is what the radalt gives. So, regardless of it being 100 feet or 1000 feet agl, you could still set your radalt for it and you have a second reference for your DH.

Your technique of setting it 50-100 feet higher is one I've heard guys use too, and it's just as effective. My point was that if you have another instrument in the cockpit you might as well use it.

My point wasn't about the approach type. My point was using a RADALT set to HAT as an indicator of the MAP isn't going to work in a place like Sedona where the runway sits on a plateau. Your RADALT, will climb hundreds of feet in seconds as the terrain climbs up to the runway. Not the best way to track your progress on glidepath for an instrument approach.

And for the record: it was a Navy instructor who passed on this opinion. Despite what's written on the ops board for my name, I'm not an international spy using ICAO terms. i learned this in the good ol' USA.

 

[insanebikerboy]

My point wasn't about the approach type. My point was using a RADALT set to HAT as an indicator of the MAP isn't going to work in a place like Sedona where the runway sits on a plateau. Your RADALT, will climb hundreds of feet in seconds as the terrain climbs up to the runway. Not the best way to track your progress on glidepath for an instrument approach.

But you're not using the radalt to track the glideslope, you're using it as a reference for HAT, which is in AGL, and which just so happens to coincide with DH. Hence, it doesn't matter what approach you're doing because the HAT doesn't change, it is what it is based on the plates.

 

[BACONATOR]

But you're not using the radalt to track the glideslope, you're using it as a reference for HAT, which is in AGL, and which just so happens to coincide with DH. Hence, it doesn't matter what approach you're doing because the HAT doesn't change, it is what it is based on the plates.

Fair enough. I can agree it is a good indicator of "DH" right in the vicinity of the runway, but depending on the terrain in the approach path, maybe not much more than that. It could get annoying to fly over a hill and have the RADALT beeping at you when you're still 100ft above MDA/DH.

 

[Pags]

Fair enough. I can agree it is a good indicator of "DH" right in the vicinity of the runway, but depending on the terrain in the approach path, maybe not much more than that. It could get annoying to fly over a hill and have the RADALT beeping at you when you're still 100ft above MDA/DH.

Use RADALT for anything that uses AGL. Everything else when it comes to instruments is done off of BARALT. Difference between the two? Use the BARALT using the local altimeter setting. Piece of cake.

All this minutia is fun, but the lions share of "instrument" flying you're going to be doing as a Navy helo guy is going to be at night over the water. And there we you use RADALT. CCAs into the boat? RADALT. Doing couplers and SAR work? RADALT. And make sure you set your DH bug to something useful as the default setting of 150' doesn't help much when you're doing overwater work at 150'.

 

[HokiePilot]

As hard as is is to write this, I agree with Otto. We execute missed approach at a perscribed altitude (MSL), not height (AGL). In level terrain, the RadAlt can be used as a good backup, but it does not tell us when to execute missed approach. There is nothing in any publication which tells us what our RadAlt will read at the proper missed approach point.

 

[yak52driver]

Here's a GPS approach from my home airport. They use DA for the altitudes on the plate. I know it's not a PAR approach, but it shows DA as a decision altitude.

 

[BACONATOR]

Here's a GPS approach from my home airport. They use DA for the altitudes on the plate. I know it's not a PAR approach, but it shows DA as a decision altitude.

See kids? DA isn't just for ICAO anymore!

 

[Pags]

As hard as is is to write this, I agree with Otto. We execute missed approach at a perscribed altitude (MSL), not height (AGL). In level terrain, the RadAlt can be used as a good backup, but it does not tell us when to execute missed approach. There is nothing in any publication which tells us what our RadAlt will read at the proper missed approach point.

You (and Otto) are correct. I guess I should have cavaeted my earlier post to say that if there's an altitude that you know to be AGL (HAT, Boat approaches) then back yourself up with the RADALT if only because it has the LAWS tones.

 

[jarhead]

DA is an RNAV term & will eventually replace DH for other approaches. Currently, PAR & ILS plates still reference DH.