Seneca down at Avalon

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.

"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.