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On Wed, 07 Jan 2004 18:25:15 GMT, "Maule Driver"
wrote in Message-Id: m: "Larry Dighera" That is a tricky approach. VOR behind and above the airport. What is it about those circumstances that causes you to characterize the Avalon VOR/DME-B approach as tricky? Thanks for taking the bait. On one hand, nothing is tricky about it if flown as published (obvious and self-evident). That's been my experience. But a bunch of folks died here by not doing so. I would expect that to be an issue with many IAPs. So what's tricky? One way of describing what's tricky is that you can fly the approach as published laterally, never descend below MDA, and crash. I see. The fact that the MAP is a DME reading is perhaps trickier than having a flag flip, needle spin,beacon sound, timer zero-out, or an intersection passed. I was taught to time all my approaches despite the lack of necessity to do so on the approach plate. GPS helps. But such is the nature of many VOR/DME approaches. I've *never* flown a VOR/DME approach using a DME so this is a bit of conjecture on my part. Granted, it's convenient if ATC has radar coverage, and can call the MAP; that's not available at AVX, IIRC. Otherwise, the pilot just includes the DME readout in his scan. For those of you familiar with it, would I be right in guessing that familiarity with VFR flight there might not make the need to climb as obvious as it is when IMC? I would guess the opposite. The mountain is clearly visible in VMC, and apparently was not immediately visible when this accident occurred. Have you flown there? Yes. I was thinking of a place like Roanoke where it is obvious after flying there VFR that there is a MOUNTAIN behind one of the runways. The mountain remains in this pilot's mindseye even when in IMC. In the case of AVX, the mountain is a bit distant and not aligned with the runway, so it doesn't have the same mental impact you describe. Looking at the approach plate for AVX, it seems like the airport and the location of the VOR are about 500' different. I'm guessing that the VOR may be on a highpoint. Flying there VFR I was trying to imagine whether one would tend not to be aware that there is a critical rise in terrain in some directions. Especially sinced the rise is not obviously aligned with a runway. But I've never flown there nor do I have a sectional. See above. So here's the trick. We're on an instructional flight, the student has done everything right but and is flying at MDA. We're looking for the airport but the student has missed the DME indication for the MAP. The instructor sees the error or not, but may decide to wait to see the student catch it (very wrong in IMC). They proceed at MDA into the only navigational aid on the entire approach. The (possible) fact that in the pilots' minds eye, they are flying to a hilltop airport surrounded by water may suggest that flying 2100 feet above the water and 500 feet above the airport is not going to result in hitting terrain. Umm. I see your reasoning, but it assumes that the pilot deliberately and/or erroneously chooses not to comply with the climb portion of the MAP. Either case is obviously fatal. Flying it as published without error of variation would of course eliminate this speculation. Flying any approach other than as published is inviting disaster, IMO. |
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Even though I'm just VFR I've been there many times and 100 OVC is
dangerously low. AVX is on the top of two mountains (they chopped of both tops and filled in the gap between) and cloud conditions can change minute by minute. No runway lighting, a cliff on each end, and mountains to the south. airnav has a nice picture of 22 on final AVX: http://www.airnav.com/airport/KAVX A tragedy, but they should have known better. -lance smith (Ron Lee) wrote in message ... Reported ceiling at 100' AGL. My limited understanding of VOR type approaches is that the MDA is in the order of 400-500' AGL. Why even attempt the approach or at least be ready to execute the missed approach. Ron Lee |
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"Larry Dighera"
Thanks for taking the bait. On one hand, nothing is tricky about it if flown as published (obvious and self-evident). That's been my experience. Mine too :-) The fact that the MAP is a DME reading is perhaps trickier than having a flag flip, needle spin,beacon sound, timer zero-out, or an intersection passed. I was taught to time all my approaches despite the lack of necessity to do so on the approach plate. But do you do it? (no need to answer) I do remember from discussions here about timing ILS's so that the LOC only can be flown if needed, that many people don't. I don't time consistently. More workload and distractions versus value of having backup information. Granted, it's convenient if ATC has radar coverage, and can call the MAP; that's not available at AVX, IIRC. Otherwise, the pilot just includes the DME readout in his scan. I didn't know that ATC does that. I've never had the MAP called for me perhaps because I've never done a non-precision with radar coverage at the altitude. Another gap in my experience. For those of you familiar with it, would I be right in guessing that familiarity with VFR flight there might not make the need to climb as obvious as it is when IMC? I would guess the opposite. The mountain is clearly visible in VMC, and apparently was not immediately visible when this accident occurred. Have you flown there? Yes. I was thinking of a place like Roanoke where it is obvious after flying there VFR that there is a MOUNTAIN behind one of the runways. The mountain remains in this pilot's mindseye even when in IMC. In the case of AVX, the mountain is a bit distant and not aligned with the runway, so it doesn't have the same mental impact you describe. That's what I was thinking. Part of our spatial awareness picture I think includes our VFR experience at a given airport. Usually that's a good thing as in, "don't let the controller vector me thru the final for more than 15 seconds because thar be mountains there". But here I was thinking it might actually be deceptive as in, "as long as I don't descend below MDA, even if I get a little sloppy out there, I won't hit anything". Clearly not the case if you read the plate but even the graphics on the NOS plate tend to hide the fact that the VOR is also co-located with an above MDA obstacle. Looking at the approach plate for AVX, it seems like the airport and the location of the VOR are about 500' different. I'm guessing that the VOR may be on a highpoint. Flying there VFR I was trying to imagine whether one would tend not to be aware that there is a critical rise in terrain in some directions. Especially sinced the rise is not obviously aligned with a runway. But I've never flown there nor do I have a sectional. See above. So here's the trick. We're on an instructional flight, the student has done everything right but and is flying at MDA. We're looking for the airport but the student has missed the DME indication for the MAP. The instructor sees the error or not, but may decide to wait to see the student catch it (very wrong in IMC). They proceed at MDA into the only navigational aid on the entire approach. The (possible) fact that in the pilots' minds eye, they are flying to a hilltop airport surrounded by water may suggest that flying 2100 feet above the water and 500 feet above the airport is not going to result in hitting terrain. Umm. I see your reasoning, but it assumes that the pilot deliberately and/or erroneously chooses not to comply with the climb portion of the MAP. Either case is obviously fatal. That's the gotcha. You could make a similar mistake at 10 different airports and live. Here, you die. Flying it as published without error of variation would of course eliminate this speculation. Flying any approach other than as published is inviting disaster, IMO. Yep. And I guess that is the bottom line. Almost always is in approach accidents. Microbursts/thunderstorms being one of the very few exceptions. |
#26
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"lance smith"
Even though I'm just VFR I've been there many times and 100 OVC is dangerously low. AVX is on the top of two mountains (they chopped of both tops and filled in the gap between) and cloud conditions can change minute by minute. It's low but "cloud conditions can change minute by minute" could be a reason to give a try. But one would *expect* the miss. No runway lighting, a cliff on each end, and mountains to the south. It's worse than that. The instrument approach is aimed directly at the mountains to the south. It is not aligned with the runway. airnav has a nice picture of 22 on final AVX: http://www.airnav.com/airport/KAVX Thanks for the pic. I was wondering what it looked like. I see why so many like to go there. |
#27
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I have put up a Topo image on my website which shows the terrain. The red
arrow is the VOR/DME approach path pointing away from the VOR (which is at top of Mt Orizaba). The altitudes/distances are close to what I see on the approach plate (see myairplane.com KAVX VOR/DME). It makes sense to turn right to the north-west on circling (and the approach prohibits circling to the south-east). Continuing on without climbing on the missed approach will send you into the VOR. One has about 2.1 miles to make the climb to 3200ft (from the airport) and about 3.2 miles from the MAP. One presumes here that the pilot did not attempt to climb. It is unfortunate here that the the final step down is at the same elevation as the top of the mountain give or take 100ft. http://snarayan.home.comcast.net/avi...x_vor_dme1.jpg "Maule Driver" wrote in message r.com... That is a tricky approach. VOR behind and above the airport. For those of you familiar with it, would I be right in guessing that familiarity with VFR flight there might not make the need to climb as obvious as it is when IMC? "R. Hubbell" wrote in message news ![]() I hadn't heard anything about this and was surprised when someone asked if I had. My condolences to the families and friends, a tragic accident. http://ntsb.gov/ntsb/brief.asp?ev_id=20031231X02110 Seems like with 5 souls that they were probably heading out for a buffalo burger and a visit to Avalon. I wonder about having pax when shooting approaches. Seems like a pretty big distraction while learning. Do the FARs prohibit pax while IFR training? R. Hubbell |
#28
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![]() "Maule Driver" wrote in message r.com... "Richard Hertz" Thanks for taking the bait. On one hand, nothing is tricky about it if flown as published (obvious and self-evident). But a bunch of folks died here by not doing so. So what's tricky? One way of describing what's tricky is that you can fly the approach as published laterally, never descend below MDA, and crash. I would not describe it that way - rather, more acurately, you fly the approach and fail to execute the missed as published. That will get you dead in many places and this is aout as "trickless" as they come. The approach is named VOR/DME - so what is the trickiness? All the information is on the approach chart. There is not much to do on the final segment - just remain at 2100, keep a heading and then make sure you know when to go missed. There is no timing on the approach chart and it seems fairly clear that the approach uses DME fixes. Well, I have to agree that it's all there and if you fly it as published, no problem. But this approach seems a little different than the 'typical' non-precision approach. I took a quick look at the first 111 approaches inf SE 2 of 4 NC & SC. I looked at at all non-precision, non-GPS-only approaches. There were 38 such approaches.32 of them had a missed approach point that was over the runway. Of the six that had MAPs short of the runway threshold, 4 of those were TACAN (military?) only approaches. Only 2 were similiar in this way to AVX. Why does it matter where the MAP is? The MAP is the MAP - if you don't have the required visual element(s), go missed. What is so tricky? What is different on this approach. It can't get any easier. Nothing wrong with different. Not necessarily tricky but I can see how a careless pilot might continue on at MDA past a MAP short of the runway while 'searching' for a view of the runway. Thinking perhaps that I can see straight down at the MAP so I'll just proceed along another mile (45 secs) until I see the runway below then I'll rack it around and circle to land. I'm not saying these folks were careless, just trying to learn something from the accident. I would say they were careless. Especially the CFII. On second thought, I'll stick with tricky. |
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"Richard Hertz"
Why does it matter where the MAP is? The MAP is the MAP - if you don't have the required visual element(s), go missed. What is so tricky? What is different on this approach. It can't get any easier. You are right, it can't be any easier. Maybe more forgiving but that's not a requirement Nothing wrong with different. Not necessarily tricky but I can see how a careless pilot might continue on at MDA past a MAP short of the runway while 'searching' for a view of the runway. Thinking perhaps that I can see straight down at the MAP so I'll just proceed along another mile (45 secs) until I see the runway below then I'll rack it around and circle to land. I'm not saying these folks were careless, just trying to learn something from the accident. I would say they were careless. Especially the CFII. Yep. |
#30
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"Maule Driver" wrote in message . rr.com...
"lance smith" Even though I'm just VFR I've been there many times and 100 OVC is dangerously low. AVX is on the top of two mountains (they chopped of both tops and filled in the gap between) and cloud conditions can change minute by minute. It's low but "cloud conditions can change minute by minute" could be a reason to give a try. But one would *expect* the miss. That's a good point. The runway is at 1600 (and surrounding area 0 MSL) I'm sure the temtation is there to scud run it at 1000 and then pop up for a straight in. I've seen people do this run, 30 miles over open water. No runway lighting, a cliff on each end, and mountains to the south. It's worse than that. The instrument approach is aimed directly at the mountains to the south. It is not aligned with the runway. Wow, didn't know that. It's hard enough to find VFR. I fly the VOR in and several miles out I look two peaks over to find the airport. Usually I still can't find it but point the airplane that direction. A couple of miles out it's often eaiser to see the airplanes in the pattern than the runway. It's one of two SoCal airports that local FBO's require a checkout before allowing you to go there with their planes. Interestingly enough there are no higher mountains nearby to the north.... airnav has a nice picture of 22 on final AVX: http://www.airnav.com/airport/KAVX Thanks for the pic. I was wondering what it looked like. I see why so many like to go there. Get the buffalo burger when there. The taste pretty much like dead cow but it's a local tradition. (secret- the burgers aren't made with the local buffalo. There aren't enough around and if they were made into burgers they would be wiped out in a few months. They are also miniature buffalo.) -lance smith |
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