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Precision Approach Minimums (ILS vs PAR)

HokiePilot

Well-Known Member
pilot
Contributor
This question has been bugging me for a while and I have never been able to get a decent answer to it. Hopefully you guys can help me.

Why are PAR minimums lower than ILS minimums?

ILSs always seem like better approaches. I have all of the information myself. Actual aircraft heading and course deviation. On a PAR, the controller is limited to deviation and assigned heading.

Is there a logical reason that PAR minimums are lower or is it just the way it is?
 

Pags

N/A
pilot
This question has been bugging me for a while and I have never been able to get a decent answer to it. Hopefully you guys can help me.

Why are PAR minimums lower than ILS minimums?

ILSs always seem like better approaches. I have all of the information myself. Actual aircraft heading and course deviation. On a PAR, the controller is limited to deviation and assigned heading.

Is there a logical reason that PAR minimums are lower or is it just the way it is?
Looking at Wikipedia, it seems that 200-1/2 are the mins for Cat I ILS approaches. The article isn't very clear as to the requirements, but it seems that you have to have some sort of coupled system to use a higher category. It would also appear that the airfield equipment needs to be higher fidelity for higher categories.
 

HokiePilot

Well-Known Member
pilot
Contributor
Yes, but that still doesn't answer the question, there are some ILSs which are capable of providing accurate guidance all the way down to 0/0. ILSs are accurate. So why in my helo tomorrow can I take a PAR down to 100 but not an ILS even if that ILS has Cat II minimums.

ILSs seem like safer, better approachs. But there are times around Whiting where I choose to take the PAR because I can get lower.
 

Renegade One

Well-Known Member
None
This question has been bugging me for a while and I have never been able to get a decent answer to it. Hopefully you guys can help me.

Why are PAR minimums lower than ILS minimums?
Is there still a "single-pilot" vs. "multi-piloted" differentiation? I seem to recall that back when dinosaurs roamed the earth, an A-6 had lower mins than an F-4 or F-14…side-by-side seating, forward vis, etc. Never mind the historical B/N reference…the question is about single vs. multiple "pilot" mins...
 

AUtiger

Crossing over to the dark side
pilot
Yes, Hornets can still only go down to 200-1/2 being under the single pilot mins
 

ssnspoon

Get a brace!
pilot
I don't really KNOW if this is why, but it makes sense to me...


ILS=Localizer+Glideslope (2 separate signals, you MUST receive them both the entire way down to break out)
Localizer=108.1-111.95 MHz (VHF)
Glideslope=329.15-335.0 MHz (UHF)

With an ILS you have two separate, LOW frequency signals displayed to you in your cockpit.

PAR=two radar returns, two separate antennas, obviously slightly offset frequencies or else they would have interference with each other.

PAR is "I" band radar and operates in the 8 GHz band. As a side note, many fighter/attack air-to-ground radars as well as missile guidance systems use this band as well (NATO countries, unclass).

ASR=2.7-2.9 GHZ

Transponders are around 1 GHz

The higher frequencies can be better localized and are "less susceptible" to interference. Think of a low rumble coming out of your bass speakers...hard to perfectly localize that sound, it sounds like it is coming from an area vice a point. Now think the same with a high frequency coming from a tweeter, you can pinpoint it easily.

So, I think the frequency leads itself to being the more robust system. Additionally, have you ever heard "ILS not monitored"? This means the tower doesn't know (no equipment telling them) if the ILS is working, maybe the G/S is down, etc. PAR's by definition are ALWAYS monitored.

Hope this makes sense.


But, it doesn't matter. OPNAV says 200-1/2 and everybody is afraid to use their special card...
 

kmac

Coffee Drinker
pilot
Super Moderator
Contributor
What does a special have to do with approach mins?
 

ssnspoon

Get a brace!
pilot
Special = no takeoff mins, but you probably would take the approach mins into account before taking off just in case you had to return(I'm thinking helo's staying local, not COD's going to far away lands). I figure that whole "sound judgement" thing would come into question if not. No matter, I have never seen anyone use theirs and the few times I thought about using mine the weather got better before it was required.
 

lowflier03

So no $hit there I was
pilot
This question has been bugging me for a while and I have never been able to get a decent answer to it. Hopefully you guys can help me.

Why are PAR minimums lower than ILS minimums?

ILSs always seem like better approaches. I have all of the information myself. Actual aircraft heading and course deviation. On a PAR, the controller is limited to deviation and assigned heading.

Is there a logical reason that PAR minimums are lower or is it just the way it is?


My take is that when these systems came into being, ground radar was much more reliable than the aircraft's ability to receive and display signals. Add in the fact that an outside person is telling the pilot what to do, instead of relying on the pilot being able to interpret his needles and fly at the same time, and you have the typical military response. Of course just because technology has come a long way doesn't mean that the military is going to change their ways just to keep up. Maybe in 20 years fleet aircraft will be certified for GPS approaches......


As an aside, have you actually gone into the tower and looked at the PAR display? Talk about an insanely archaic system. I know some have been upgraded, but damn I'm amazed PAR got certified to the mins it did. Sure the radar was accurate, but the operator side of the interface is shit.
 

Hozer

Jobu needs a refill!
None
Contributor
^^Ha, this brings back some great memories of PAR training/currency evolutions...hearing "Over, the landing threshold" and seeing grass.

policestation.jpg


Scene from "Bladerunner" where you hear PAR lingo...
 
Last edited:

statesman

Shut up woman... get on my horse.
pilot
Yes, but that still doesn't answer the question, there are some ILSs which are capable of providing accurate guidance all the way down to 0/0. ILSs are accurate. So why in my helo tomorrow can I take a PAR down to 100 but not an ILS even if that ILS has Cat II minimums.

ILSs seem like safer, better approachs. But there are times around Whiting where I choose to take the PAR because I can get lower.


Those are CAT II and III ILS. Your aircraft has to be certified for CAT II in order to use the CAT II mins, or the CAT III in 0/0 situations.


Maybe I'm not understanding your question though.
I don't think any Navy a/c are certified past CAT I.
 
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