obstacle clearance on a circling approach

bLizZuE

bLizZuE

Calling for engine starts en français
I know the radii, but I can't find anywhere in the FARs or the AIM about how MUCH obstacle clearance is guaranteed for each catagory!

Help...
 
look at the inst app procedures book and look at the circle to land section, it says there 300 obs clearance is provided

Edit: I'm so nice, I went down to my car, got my book and looked for ya :D

go to 5-7, its above the Radii figure.

I believe its 300 due to

75 feet altimeter error
100 feet pilot deviation
125 transponder pres alt error

thats worst case scenario if everything was on the negative side

correct me if I'm wrong
 
taseal said:
I believe its 300 due to

75 feet altimeter error
100 feet pilot deviation
125 transponder pres alt error

thats worst case scenario if everything was on the negative side
Click to expand...

Unless you read that somewhere, I suspect you're trying to ascribe too much logic to an arbitrarily derived figure. The transponder figure alone is irrelevant, since it plays no role in obstacle clearance. While the 75 feet altimeter error is used in pilot literature as a gauge of altimeter system reliability, I've never seen that figure used in TERPS related documentation. And to allow only a 100 feet of pilot-induced error before the pilot hits something would be very alarming.

But, as others said, 300 feet is the correct number.
 
Does it change for each category? I'm thinking no...

Thanks for your help guys. I knew it was 300, but I couldn't put my finger on a source!
 
surreal1221 said:
I should know this. . .but. . .

http://whitts.alioth.net/Pageg35 All About Mimimums.htm

This website says it provides 300' obstruction clearence within the radius.



No source listed.
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tgrayson said:
Unless you read that somewhere, I suspect you're trying to ascribe too much logic to an arbitrarily derived figure. The transponder figure alone is irrelevant, since it plays no role in obstacle clearance. While the 75 feet altimeter error is used in pilot literature as a gauge of altimeter system reliability, I've never seen that figure used in TERPS related documentation. And to allow only a 100 feet of pilot-induced error before the pilot hits something would be very alarming.

But, as others said, 300 feet is the correct number.
Click to expand...

I mentioned transponder because ya know when you're low the controller goes 'low alt alert, check alt immediately etc etc'

I kinda just made that up as to why it might be 300, thats why I said 300, so maybe right, maybe wrong heh...
 
taseal said:
I mentioned transponder because ya know when you're low the controller goes 'low alt alert, check alt immediately etc etc'
Click to expand...

I've never had a controller say this when I'm inside the FAF or have all ready commenced the circle.

Is that normal?? Are they even watching your mode C hit when you're circling??
 
Hacker15e said:
I've never had a controller say this when I'm inside the FAF or have all ready commenced the circle.

Is that normal?? Are they even watching your mode C hit when you're circling??
Click to expand...

No, because you're on a segment of an already established approach.

Low altitude alerts will occur (traditionally) in areas where an MVA is being penetrated by a pilot that failed to maintain his/her latest altitude assignment that was say AT the MVA, or slightly above it.
 
The system for low altitude alerts (in the NE at least) predicts your descent rate and if it sees you'll hit the specified altitude (mda) before a fix (map), say on a localizer approach, it'll ring the bell.

I got one every single time I shot the LDA into Hartford, CT.
 
surreal1221 said:
No, because you're on a segment of an already established approach.
Click to expand...

You can still get them in this situation. I've heard our local tower relay a warning to an aircraft on a circling approach. I have the impression that each facility can program its MSAW as it desires.

The 7110.65 contains language warning a pilot of what MDA/DH is, so it's obviously not limited to MVA. You can also get them with a high rate of descent on a non-precision approach (The MSAW software looks at your trend and freaks.)
 
surreal1221 said:
No, because you're on a segment of an already established approach.

Low altitude alerts will occur (traditionally) in areas where an MVA is being penetrated by a pilot that failed to maintain his/her latest altitude assignment that was say AT the MVA, or slightly above it.
Click to expand...

i was told this while shooting a LOC into FXE, we were about 500 agl i'd say...
 
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