MikeDs GCA (ASR and PAR) approach review.

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MikeD

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Due to limited information provided in the AIM, and by popular demand, I'm expanding on information provided in the AIM concerning radar approaches.................


There are two basic types of radar approaches (or GCAs, Ground Controlled Approaches); Airport Surveillance Radar (ASR) and Precision Approach Radar (PAR). The surveillance approach provides course and range information and is classified as a non-precision approach, while the PAR additionally provides glidepath information, thus giving it precision capability. On ASR approaches, the final controller will, on request, provide recommended altitudes on final to the last whole mile that is at-or-above the published MDA. Recommended altitudes are computed from the start descent point to the threshold of the runway. ASRs have an accuacy of bringing the pilot within 500 feet of either runway edge, while PARs are accurate to within 25 feet either side of runway centerline. For this reason, pilots flying an ASR to parallel runways should take caution for assuring that they're lined up with the correct runway upon breakout. ATC uses the normal controller's scope to perform ASR approaches, whereas PAR approaches utilize an entirely separate radar system from the normal ATC radar.

If available, prior to flying a GCA, select a back-up approach (compatible with existing WX and aircraft capabilities) to use if the controller's radar goes down, or if the aircraft goes NORDO during the approach final segment. It is important to have a back-up plan since radar approaches are so comm-dependant. In the event of lost comm, the pilot is automatically cleared to fly any published approach unless ATC previously issued a specific IAP to fly in the event of lost comm. To insure lost comm hasn't occurred, the pilot should attempt contact with ATC if no transmissions are heard for:

-1 minute while being vectored in the radar pattern
-15 seconds while on ASR final
-5 seconds while on PAR final

If the pilot goes NORDO, or the ATC radar fails and you're unable to maintain VFR, transition to your back-up approach. Intercept the approach at the nearest point that will allow for a normal descent rate and not compromise safety. Maintain the last assigned altitude or MSA/ESA, whichever is higher, until established on a segment of the published approach. If no back-up approach is available that's compatible with your aircraft or with the exisiting WX, advise ATC upon initial contact of your intentions in the event of lost comm. If local conditions dictate, ATC may specify which approach to fly in the event of lost comm. Either way, it's the pilot's responsibility to determine the adequacy of any NORDO procedures issued by ATC.

Since the radar approach relies entirely upon voice comm instructions issued by ATC, it is imperative that the pilot repeat all headings, altitudes (departing and assigned), and altimeter settings, like you'd normally do, until the final controller advises "do not acknowlege further transmissions". After this point, the final controller will query you if he needs a reply on anything, such as acknowleging landing clearance. And the standard still applies of keeping radio comm clear/concise/correct, especially during high-density radar traffic operations.

During both types of radar approaches, ATC will vector you to the final segment prior to handoff to the final controller. Each radar approach is on it's own discreet frequency so as not to be interfered with by other transmissions; you'll only hear you and the final controller once handed off to his frequency. The vector to dogleg final (transition to final) encompasses all maneuvering up to a point where the aircraft is approximately 8 NM from touchdown and inbound. ATC will, at a minimum, provide the pilot with position information at least once prior to handoff to the final controller. Prior to this time, have your appropriate approach/landing checks accomplished (per your ops), and have a descent rate predetermined. For example on the PAR, if the glidepath is known to be 3 degrees, and your final approach groundspeed is 160 kts, then your initial descent rate would be 800 fpm.

(groundspeed x 10)/2 ; or (160 x 10)/2= 800 fpm for a 3 degree GP.

Final segment ASR: The ATC final controller will inform the pilot of the runway to which the approach will be made, the straight-in MDA (if a straight-in), the MAP location, and advanced notice of where the descent to MDA will begin. If terminating an ASR to a circling approach, the pilot must furnish the aircraft's approach category to the final controller, the final controller will then issue the circling MDA appropriate to the runway the pilot is circling to and the aircraft's category, as applicable. On final, upon reaching the descent point, the final controller will advise the pilot to "begin descent," advising the pilot of any descent restrictions if any exist. Use normal non-precision descent rates in order to arrive at MDA with time to acquire the runway environment and make a normal descent to landing. The final controller will issue course guidance when required and will give you range information each mile while on final. This guidance will be provided until the aircraft is over the MAP, unless the pilot requests discontinuation of guidance. The final controller will advise when you're at the MAP. At that point, the pilot must advise that he either 1. "Runway in sight, landing assured"; or 2. "Executing missed approach" with reason, at which point ATC will issue missed approach instructions (as before, in the event of any lost comm at this time, follow your lost comm instructions issued by ATC.) The final controller will also, during the descent on final, issue the landing clearance to the pilot that he's pre-coordinated with tower. Radar approaches do not utilize frequency changes after switching to the final controller, since the final controller will also initially work your missed approach, were you to do one. On landing rollout, switch to tower and advise them you're on frequency. Ex: "Tower, Harlot 41, GCA rollout..." Upon request, the final controller will provide the pilot with recommended altitudes on final at each mile to the last whole mile that is at or above the published MDA. Due to possible different locations of the MAP, recommend altitudes may place you at or slightly prior to, the MAP. This should be considered in relation to the normal VDP for your particular aircraft, since depending on the MAP location, descent from the MDA, once runway is in sight, often will have to be initiated prior to reaching the MAP in order to allow for a normal descent to landing.

Comm will sound like this:

"8 miles from touchdown, slightly left of course, turn right heading 140, begin descent."

"7 miles from touchdown, turn left heading 130, recommended altitude 6,500" (assuming recommended altitudes requested)

"on course"

"6 miles from touchdown, on course, recommended altitude 5,700"

and so on.....

Final Segment: PAR: PAR final approach starts when the aircraft is within the range of the PAR radar, which is separate from the normal ATC radar. This is normally at the same 8 NM from touchdown point as with the ASR approach. Upon switching to the final controller, and approximately 10-30 seconds prior to reaching the descent point, the final controller will usually ask what the aircraft's heading is reading so he can use this as a baseline for corrections compared to what he sees on his scope. Additionally, the final controller will advise the pilot that he's approaching the glidepath and additionally that "wheels should be down" (for military). Upon reaching the descent point, the final controller will advise "begin descent" then begin the azimuth and elevation corrections about every 5 seconds. Establish the predetermined rate of descent, and utilize power or drag devices as required to maintain desired airspeed or AOA. When the airspeed or AOA and and glidepath are stabilized, take quick note of the power, attitude and VVI, and utilize these indications as a baseline for corrections for the remainder of the approach. ATC will issue course and glidepath guidance and will provide corrections along with trend information. Examples: (note: no callsigns used since you're on a discreet frequency)

"7 miles from touchdown, on glidepath, on course."

"Slightly below glidepath, on course, 6 miles from touchdown"

"slightly below glidepath going further below, 5 miles from touchdown"

"slightly below glidepath coming up, slightly left of course, turn right heading 135, 4 miles from touchdown.."

Position information for course will be noted as slightly/well left/right; and for glidepath will slightly/well above, slightly/well/dangerously below. Trend information will be given as "going further below", etc. As with an ILS approach, make all turns within the "heading bars" on the HSI. In any event, course corrections from ATC won't be much more than 3-5 degrees. Follow corrections as soon as ATC gives them. For glidepath corrections, pitch changes of no more than 1 degree are normally sufficient. Heading corrections should also not be made with an angle of bank more than the correction to be made, otherwise an overshoot could result. Do not exceed 1/2 standard rate turn when makiing heading corrections once the descent has been made on the final segment. After a new heading is issued by the final controller, he assumes that heading is being maintained. Additional corrections are being made based on the last heading given.

The final controller will advise the pilot when he's reached the published DH. DH is determined in the cockpit as read on the altimeter, or when advised by the final controller, whichever occurs first. The final controller will continue to provide advisory course and glidepath guidance until the aircraft passes over the approach landing threshold at which time the controller will advise "over the landing threshold". At DH, if proceeding missed, advise the final controller and the procedures are the same as with the ASR. If landing, advise the final controller when you have the runway in sight with landing assured, and upon rollout, contact/switch to tower and advise them. Ex: "Tower, Harlot 11, PAR rollout". Like the ILS, the PAR is a straight-in procedure only, with no circling minima existant. PAR are certified down to 100' and 1/4 mile, more accurate than the ILS (Cat 1) 200' and 1/2.

No-Gyro Final Segment: If your heading indicator or HSI should become inoperative during the approach or prior, advise ATC and request a No-Gyro approach. The final segment for this approach can be either ASR or PAR. Perform turns during transition to final by establishing an angle of bank that will approximate a standard rate turn, not to exceed 30 degrees. Perform turns on the final segment by establishing an angle of bank on the attitude indicator that will approximate a 1/2 standard rate turn. If unable to comply with this, advise the final controller so he can manually determine lead-points for turn and heading corrections. Initiate turns immediately upon hearing "turn left/right". Stop turns when hearing "stop turn". Acknowlege these commands until advised by the final controller to no longer acknowlege further transmissions. Do not begin using half-standard rate turns until advised to do so by ATC. ATC may want to continue standard rate turns even on final if abnormal conditions exist such as strong crosswinds or turbulance.

MD
 
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Read first (
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), then printed and filed...

Thanks so much MikeD, for taking the time to do that. I do practice ASR approaches all the time with my students, and I learned some new things from this that aren't even mentioned in the AIM.

Thanks again!
smile.gif
 
[ QUOTE ]
Read first (
wink.gif
), then printed and filed...

Thanks so much MikeD, for taking the time to do that. I do practice ASR approaches all the time with my students, and I learned some new things from this that aren't even mentioned in the AIM.

Thanks again!
smile.gif


[/ QUOTE ]

hehe. make military pilots out of you guys yet. Just kidding. Seriously though, the AIM does seemingly short-change civilian pilots on the radar approach procedures with it's limited info, even though these approaches are an approach you could get assigned or need; regardless of what some others think about what civil pilots need and don't need. They just don't know.

BTW, what field to you practice these at?
 
[ QUOTE ]
hehe. make military pilots out of you guys yet.

[/ QUOTE ]

Actually, I haven't ruled that out yet (or at least trying). I'll be finishing my Bachelors soon, so I'm looking seriously at that as an option. My grades were/are good, my eyes are corrected to 20/20, and I have a relative who flew A-10's then later F-16's for the ANG (174th TFW out of SYR) for many years- its a connection I'd really like to use if possible.


[ QUOTE ]
BTW, what field to you practice these at?

[/ QUOTE ]

Akron-Canton, OH (KCAK).
 
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make military pilots out of you guys yet.

[/ QUOTE ]

I too thought about this but I think my timing is a little bad. I still retain my British citizenship and am in the process of apply for my US naturalization. I am 29 now and I dont think the paperwork will go through before my 30th birthday, which I think is the cutoff for the ANG. I should of pursued this whole aviation thing much sooner I guess....but better now then never
 
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, and I have a relative who flew A-10's then later F-16's for the ANG (174th TFW out of SYR)


[/ QUOTE ]

174th? The Girls fom Syracuse? Just kidding. Neat unit. Too bad they had to take off the "Boys from Syracuse" inscription on their jets. Results from some of the "scandals" the NY ANG has had.

Nice flying the ASRs with more background on them workings? They're not difficult at all, but it's good to know their limitations and what to expect (and what's expected of you) when flying them. Also, controllers have to maintain currency on these approaches at airports that have them; so many controlled as final controller per month. So they appreciate you flying them too.

You can see at KCAK that with ASRs available to 6 different runways (3 runways, 2 directions each), there's many different variables. KCAKs MDA vary from 1600/24 (400-1/2) for a Cats A/B/C ASR Rwy 1 to 1640/1 (500-1) for a Cats A/B ASR 14. Circling MDA is also different for each Category which is why you must advise ATC so he can give you the correct MDA. Category A/B bein 1680-1, C being 1680-1.5, while D is 1780-2.

MD
 
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You can see at KCAK that with ASRs available to 6 different runways (3 runways, 2 directions each), there's many different variables.

[/ QUOTE ]

Yeah, I always have the plate in front of me, cause it seems like I get a different runway every time I do it. And I get to do them quite frequently- my boss requires all pilots flying our airplanes to do them when they get checked out, and as part of their 6-month IPC.

[ QUOTE ]
Also, controllers have to maintain currency on these approaches at airports that have them; so many controlled as final controller per month. So they appreciate you flying them too.

[/ QUOTE ]

Yeah, I actually had a controller thank me for keeping him current. That puzzled my student...
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[ QUOTE ]
Nice flying the ASRs with more background on them workings? They're not difficult at all, but it's good to know their limitations and what to expect (and what's expected of you) when flying them.

[/ QUOTE ]

Well...it will be now! Thanks again!
smile.gif
 
Re: MikeDs GCA (ASR and PAR) approach review. *DELETED*

Post deleted by MikeD
 
Thanks for the article, Mike. It's printed and stored in my notes. But I'm confused about one thing. I thought that if I had to use an ASR approach for real, it would be because my navaids went down for whatever reason. Why else would I be doing them, asides from practice? And if this is the case, in your article, you talk about having a back up approach ready. How can I have a back up approach if my navaid is out?
confused.gif
Hope that makes sense. Thanks
 
[ QUOTE ]
Thanks for the article, Mike. It's printed and stored in my notes. But I'm confused about one thing. I thought that if I had to use an ASR approach for real, it would be because my navaids went down for whatever reason. Why else would I be doing them, asides from practice? And if this is the case, in your article, you talk about having a back up approach ready. How can I have a back up approach if my navaid is out?
confused.gif
Hope that makes sense. Thanks

[/ QUOTE ]

Where did you get the idea that ASR/PAR approaches are some kind of emergency approach only? They're published approaches just like any other approach (published in the sense that the field will have mins published for them). They're not just for navaid-out only, or any other emergency only. A time when you may use them is these examples, which has happened to me numerous times: Some fields may have an ASR approach only to the duty runway. Once, going into KABQ, the duty runway was 35 due to winds. Additionally, the ceiling and viz weren't great (variable between 400-500/1.5), so I had a choice: 1. Fly the VOR to 8 with a pretty sporty crosswind and circle to 35, with circling mins that are @5840' or so; or 2: Take the straight-in ASR to 35 with a headwind, not have to worry about circling with heinous winds, buy an additional 100' of WX availability, and an extra 100' of MDA. Which would you choose? Second situation was again low WX of 200-3/4 at a field. ILS was only to one runway, and the opposite direction was in use. So now, it's take a LOC BC (800-2 WX required), or the PAR which was up and available (100-1/4 WX required). Which would you do?
 
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[ QUOTE ]
hehe. make military pilots out of you guys yet.

[/ QUOTE ]Not likely
wink.gif


But a great write-up!

[/ QUOTE ]

LOL.!

Thanks. It's one of those that's gotten buried in the way-back machine of Tech Talk. But I figured I'd write it because, as good as the AIM and other FAA publications are, they really do skimp (IMHO) on discussing these approaches, which as you know for the ASR, is available at a number of fields nationwide, with the PAR being available at most all military fields. Will civilians use it much? I don't know. But it's still a tool there that's available should one ever need to use it.
 
[ QUOTE ]

Where did you get the idea that ASR/PAR approaches are some kind of emergency approach only? They're published approaches just like any other approach (published in the sense that the field will have mins published for them). They're not just for navaid-out only, or any other emergency only. [ QUOTE ]


Whenever I look up ASR/PAR/No Gyro approaches, they are written as if they are not "regular" approaches, such as ILS, VOR, etc. In the Jepp Instrument book, these radar approaches are described under "Emergency Approach Procedures". And people talk about controllers welcoming these approaches because they can stay current...again, a non regular situation.

Your examples, however, put them in a different perspective. It made perfect sense to request these approaches under the conditions you had. Thanks for clearing things up.

Fred
 
[ QUOTE ]

Whenever I look up ASR/PAR/No Gyro approaches, they are written as if they are not "regular" approaches, such as ILS, VOR, etc. In the Jepp Instrument book, these radar approaches are described under "Emergency Approach Procedures". And people talk about controllers welcoming these approaches because they can stay current...again, a non regular situation.

Your examples, however, put them in a different perspective. It made perfect sense to request these approaches under the conditions you had. Thanks for clearing things up.

Fred

[/ QUOTE ]

That's because those pubs you mentioned are full of crap in regards to these types of approaches. These are official Instrument Approach Procedures, they're just too lazy to cover them appropriately....so I did their job for them.
 
Thanks for the write up Mike. Informative as always. I've shot the PAR into Yuma a few times now in both a Cessna and Seminole. Fun stuff. The first few times I had my student set the ILS up for additional course guidence but the last time we did it with just the PAR. We had a student controller who did a pretty good job I thought. One interesting thing was that when he called 4 miles from touchdown he added that there was a raised arrestor cable 1700 feet from touchdown end. I asked him to verify this but he just kept giving course guidence and never acknowledged that there was a cable. Keep in mind it was dark out. So about 1mile out I stated I was going to break off the approach unless he confirmed that the runway was clear. He stated again there was a cable and continued giving course guidence. So we ended up going missed and then entering the pattern for another runway. I'm not sure if they actually expected us to land with the cable or not... either way it as a little strange.

Ethan
 
[ QUOTE ]
Thanks for the write up Mike. Informative as always. I've shot the PAR into Yuma a few times now in both a Cessna and Seminole. Fun stuff. The first few times I had my student set the ILS up for additional course guidence but the last time we did it with just the PAR. We had a student controller who did a pretty good job I thought. One interesting thing was that when he called 4 miles from touchdown he added that there was a raised arrestor cable 1700 feet from touchdown end. I asked him to verify this but he just kept giving course guidence and never acknowledged that there was a cable. Keep in mind it was dark out. So about 1mile out I stated I was going to break off the approach unless he confirmed that the runway was clear. He stated again there was a cable and continued giving course guidence. So we ended up going missed and then entering the pattern for another runway. I'm not sure if they actually expected us to land with the cable or not... either way it as a little strange.

Ethan

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Check the airport diagram. At least in the NOS/NACO ones, when you see the bi-directional arrows on runways 3-21 L/R labled "E-28" at NYL, that's the location of the arresting gear cables. They're used by tailhook-equipped aircraft for wet runway landings, as well as emergency use for aircraft with brake problems. The USN E-28s are similiar to the USAF BAK-12s in that they use a series of small rubber donuts laid across the runway that support a small cable and keep it about 3 inches off the runway. Shown in this picture is a BAK-12 cable, though in this link is pictured the BAK-12 combined with the BAK-14 system that allows the BAK-12 cable to retract into a slot in the runway; whereas the normal BAK-12 has no slot and is always "in battery" (unless disconnected). On a sidenote, Tuscon International has the BAK-12/14 system on it's runway 11L/29R. To see on an actual runway where these systems are located, they're marked by painted yellow circles across the runway at the cable location, as well as a lighted sign abeam each side of the system which is a lighted yellow circle on a black background, in normal airport-signage presentation.

http://www.naco.faa.gov/content/naco/online/airportdiagrams/00511AD.PDF
http://www.esco-usa.com/mil/bak14.html

From the FAA AC 150/5220-9:

http://www1.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/8dd3ae349c0bd4e786256c750060f1dc/$FILE/150-5220-9.pdf

So far as the NYL controller, it's their job to advise of any cables for landing aircraft, especially at USN bases. If a guy is landing with hook down, and he doesn't desire an approach-end engagement (or short-field arrestment for you Navy types), then he knows to land long by about 2000' in this case, so he can make a departure-end engagement (long-field arrestment). So far as you're concerned, you can land and have no problem, but if you land prior to the E-28 cable, just know you'll run over the cable and expect that. It won't hurt the plane at all, and definately no need to go around for fear the runway isn't clear; it's perfectly clear. NYL was one of my regular routes back in the cargo days, and I used to land on 3/21 L/R there often, rolling over the cables in C-207/208s and PA-31s, with no problem. The cable won't "bounce up" since it's strung taut between the two energy absorbers on each side of the runway. As a technique though, I'd usually land, roll over the cable with the mains, then lower the nose to the runway just to take it easy on the nose gear. That, or you can land long, since you still have 11,000+ of runway left. for takeoff though, most military towers will have civilian aircraft taxi into position and hold beyond the cable, then issue takeoff clearance. Local procedures may vary. When a Southwest Airlines 737 landed at Nellis AFB the other week, the plane slowed to nearly a crawl before crossing the departure-end BAK-12 there, then taxiied over it. I was waiting to takeoff opposite direction, and thought it rather funny, since for a large plane like that, it won't get damaged by the cables, although it might damage the cables with it's weight, so that might have been the reason. I was just annoyed at the delay.
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One last thing on PARs. There's not much time to ask a question to ATC, since the final controller is guiding you down with commands about every 5 seconds. So if asking a question, it better be a good one, since the controller has enough work to do guiding you. In any event, the arresting gear is depicted on the airport diagram, so dark or not, one shouldn't really be surprised when advised by the controller of the standard piece of runway equipment that's there daily, although I can fully understand possibly not knowing if there was a particular reason he was advising you of this, or not.
 
Anyone wanting to get experience with radar approaches, especially PAR, will want to find a way to get them soon. They're rapidly beginning to disappear around the continental US.
 
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