"Jim Baker" wrote in message ...
"Jeremy Lew" wrote in message
...
Doesn't filing to an IAF imply that you know before you take off which
approach you'll be flying? It seems almost useless, since the "in use"
approach may be something entirely different once you actually get there.
Am I missing something?
What you're missing Jeremy, IMO, is that you'll know, or should know, before
you leave on an IFR flight which RWY is probably currently active at the
airport by listening to your predeparture WX briefing and figuring which RWY
will most likely be active upon your arrival.
Just my opinion, but if you're making a flight of any duration (3-3 1/2 hrs)
weather has a way of changing esp. if it's low enough that an approach
looks likely.
That's not to say that a preflight wx briefing and a careful preflight
review of the most likely approach aren't of value -- they are.
But filing to an IAF for a particular approach just may not be a
reasonable idea, regardless of preflight wx and wx changes enroute.
If the airport is busy and has radar, the IAF may be the last place
you'll ever be directed to fly and the least desireable route to the airport.
If the IAF is not an H-class VOR, it's not likely to be in the ATC
database of the originating ATC facility if you're making a trip of
any duration, so filing to an IAF only bolixes the works.
IMHO, it's much better to look at the specifics of the situation
than to make a general rule like "file to an IAF".
If you have an ILS on board, for instance, pick the IAF as your last point
in the route of flight for an ILS approach serving the RWY you expect to be
active. That's the best you can do and is much better, IMO, than not making
any plan because the RWY might be different than the one you picked based on
the predeparture WX briefing.
It may be better than "not making any plan", but it's not necessarily a
realistic or reasonable plan.
Here's a specific example. Consider the ILS 26L approach into KSUS,
which one can look at online at AOPA or myairplane if one likes.
This is the favored runway and the runway into the most common wind
directions, so it's a reasonable guess if an instrument approach is
needed, that's the one.
There are two IAF. One is Troy (TOY), VOR to the E. It's not an
H-class VOR, and if I'm starting my flight in mid-Ohio or MN or
GA, ATC may or may not have TOY in the system. Moreover, to get
from TOY to SUS the direct route takes one right across the
approach paths into KSTL. Is that gonna happen, no. Is that what
I'd choose in the event of a comm failure, no way.
The other IAF is the LOM, Eaves, and the betting is good outside
KC center turf no ATC computer has heard of it.
Coming from the north, I'd file to STL, which is an H-class VOR
and a reasonable bet that most ATC computers have heard of it.
Coming from the south, I'd file to Meram, an airway intersection
south of Eaves, with a remark Meram is STL170018. Coming from
the E. or W. would depend on my exact heading -- might still be
the same. Again, reason, I think ATC computers are likely to know
where STL is so anything defined by STL is good.
My home airport, 1H0, is served by GPS approaches. Would I file to
one of those IAFs, no way. No ATC database outside the "home boys"
will ever have heard of them.
$0.02,
Sydney
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