Max speed on a DME arc?

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Nice airport you guys have up there!!

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Yeah it's not bad, as long as you aren't there around 9 PM on a weekday, and you hear the dreaded "Lafayette tower has suspended operations, 9 aircraft in left traffic, 8 in right traffic and a Cessna inbound from the north. Have a good night"
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Personally. I've never flown with an RMI. I fear technology. Give me two Navs and a DG anyday.

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Have you flown with an HSI yet? They're a big step up in the SA dept, especially the combination HSI/RMI jobs like MikeD described that the military has.
 
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Yeah, had an HSI in the Seneca, may it rest in peace....

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Man, I flew a Seneca today for the first time...a very nice Seneca....2002 model!!!

Let's just say that I could get spoiled very, very quickly!!!

[image]http://www.flywithlloyd.com/images/pa34cock.jpeg[/image]
 
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Nice airport you guys have up there!!

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Yeah it's not bad, as long as you aren't there around 9 PM on a weekday, and you hear the dreaded "Lafayette tower has suspended operations, 9 aircraft in left traffic, 8 in right traffic and a Cessna inbound from the north. Have a good night"
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Ha!! We've got all of that down in Murfreesboro, minus the tower to help you out!!
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Yeah, had an HSI in the Seneca, may it rest in peace....

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Man, I flew a Seneca today for the first time...a very nice Seneca....2002 model!!!

Let's just say that I could get spoiled very, very quickly!!!

[image]http://www.flywithlloyd.com/images/pa34cock.jpeg[/image]

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I see there is a S-Tec AP.

How is it in that airplane? Some of our seminoles have them and they suck. That is all I can say, THEY SUCK.
 
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I see there is a S-Tec AP.

How is it in that airplane? Some of our seminoles have them and they suck. That is all I can say, THEY SUCK.

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Man, I'll take a KAP-140 anyday! The S-tec in that airplane does this funky-a$$ pitch oscillation, and it's continuously +/-100 feet.
 
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Ya mean once you get to the airlines, there's no more "turn 10, twist 10?" Where's the fun in that?



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I'd like to have some fun with it, but many of the approaches we fly in Mexico are arcs, and some are in very mountainous terrain. There is an approach into Saltillo that is notorious-you are very busy, and I keep the autopilot on as long as possible. It can fly an arc better than I can, and won't forget to turn inbound. Too much at risk.
 
Seneca? Wings finally getting a twin, or did you get lucky? BTW, I was flying an old Seneca I. A 2002 model would only be in my dreams.....
 
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Wow. That's fast. I was thinking TERP's would call for a lower speed but I don't have a copy handy. Got into a situation in the sim last week where we really needed to be on the ground fast and the Capt slowed way down cause it was non-radar on a 7 DME arc to an ILS. He was worried about overshooting the inbound turn and slowed to about 160. I was thinking 200 would be okay. We actually had to repeat the scenario cause he was so slow. Made it in the second time, okay, but I was still wishing he'd have picked it up. Just wanted to give my fellow gouge seekers something to think about and a hard number to reference when the sim instructor says "you were too fast on the arc".

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If I remember back to my old, very old Air Force days the "problem" of overshooting an "arc to a radial", or vice versa was to use 1% of the GS as a lead point. That way the variance in speed was taken care of. Flew many a penetration/approach with an arc and seem to remember the 1% thing worked pretty well.
 
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Wow. That's fast. I was thinking TERP's would call for a lower speed but I don't have a copy handy. Got into a situation in the sim last week where we really needed to be on the ground fast and the Capt slowed way down cause it was non-radar on a 7 DME arc to an ILS. He was worried about overshooting the inbound turn and slowed to about 160. I was thinking 200 would be okay. We actually had to repeat the scenario cause he was so slow. Made it in the second time, okay, but I was still wishing he'd have picked it up. Just wanted to give my fellow gouge seekers something to think about and a hard number to reference when the sim instructor says "you were too fast on the arc".

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Is overshooting the turn in 757 even a possibility??? I would have thought that that the FMS(I think Boeing calls it FMC) would be smart enough to lead the turn sufficiently based on closure rate. Just the other night I joined a localizer from basically a 90 degree intercept at 240 kias and did go thru the localizer a bit but only about a 1/2 'dot' -- and keep in mind that the autopilot in the CRJ is trash. Well maybe not trash but definatley not the best I've ever used.

Jason
 
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Seneca? Wings finally getting a twin, or did you get lucky? BTW, I was flying an old Seneca I. A 2002 model would only be in my dreams.....

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HA!! Of all things, Wings wouldn't commit to a 2002 Seneca!!
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Just a lucky trip.
 
The 757 doesn't just roll onto the LOC like you would think. Intercepting the LOC isn't an LNAV function and I think that's why. I've seen some guys use the LNAV course for the initial LOC intercept for that exact reason and it seems to work pretty well. It's not really the way we are trained, though, and I suppose you could forget to arm the approach mode if you did it that way.
 
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If I remember back to my old, very old Air Force days the "problem" of overshooting an "arc to a radial", or vice versa was to use 1% of the GS as a lead point.... Flew many a penetration/approach with an arc and seem to remember the 1% thing worked pretty well.

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So at 200 KT, you would begin turning onto your final approach course 2 degrees prior? That's a good tip.
 
No. It's a DME mileage thing. One percent of your GS equals you lead on turn. If you are doing 200K, lead your turn by 2 miles.
 
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Just the other night I joined a localizer from basically a 90 degree intercept at 240 kias ...
Jason

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The FMZ in the CX will automatically switch from LNAV to LOC (short range) once APP is armed, and the CDI needle for short range comes "alive." It will switch from magenta needle to green needle and role right onto course. It's a thing of beauty! No button pushing required.
 
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No. It's a DME mileage thing. One percent of your GS equals you lead on turn. If you are doing 200K, lead your turn by 2 miles.

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Hey, that's "Riddle"!
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Remember the formula for computing standard rate turns -- (TAS * .1) + (TAS * .1)/2
 
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If I remember back to my old, very old Air Force days the "problem" of overshooting an "arc to a radial", or vice versa was to use 1% of the GS as a lead point.... Flew many a penetration/approach with an arc and seem to remember the 1% thing worked pretty well.

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So at 200 KT, you would begin turning onto your final approach course 2 degrees prior? That's a good tip.

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It's the same as these formulas:

radial to arc: TR=IMN - 2; or mach minus 2, where mach equals miles per minute. In my case, 300 knots equals 5 miles per minute. So 5 minus 2 equals a 3 mile turn radius, or lead the radial to arc by 3 miles.

arc to radial: 60 to 1 rule. 60/DME arc x TR, DME arc distance divided into 60, multiplied by Turn Radius. So, on a 15 DME arc, 60/15 equals 4....times 3 (TR) equals 12. Or make the lead radial 12 degrees short of the desired radial.

Yes, it's public math, but it's pretty simple public math that can be figured out in pre-mission planning, or enroute.
 
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If I remember back to my old, very old Air Force days the "problem" of overshooting an "arc to a radial", or vice versa was to use 1% of the GS as a lead point.... Flew many a penetration/approach with an arc and seem to remember the 1% thing worked pretty well.

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So at 200 KT, you would begin turning onto your final approach course 2 degrees prior? That's a good tip.

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NO, NO, NO....2 miles.

So....if you are on a 15 mile arc, each degree is 1/4 mile, (1 degree at 60 miles equals 1 mile) hence you would have to begin your turn at 8 degrees prior to the inbound radial. (2 miles divided by ¼ mile per degree)

REMEBER...1% of the GS which is in miles (distance) hence the lead point has to be in miles (distance).

This was all done with little more than and RMI and DME. None of that fancy GPS stuff. Without a GS indicator, you actually had to do a little more math to get your GS, like take into account the wind.
 
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NO, NO, NO....2 miles.

So....if you are on a 15 mile arc, each degree is 1/4 mile, (1 degree at 60 miles equals 1 mile) hence you would have to begin your turn at 8 degrees prior to the inbound radial. (2 miles divided by ¼ mile per degree)

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Excellent - that make sense. Sounds like 10 degrees is a rough rule-of-thumb for >200 knots. Or I'll just watch the FMS do it.
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