"Daniel Roesen" wrote in message
...

Timothy Witt wrote: "they had been cleared direct to the IAF", e.g.
"turn X heading Y direct ROUND HILL, cleared VOR/DME 12".


Who's Timothy Witt?

"At 10:51 the [Washington] center controller gave the flight a heading of
090 to intercept the 300-degree radial of the Armel VOR, to cross a point 25
miles west of Armel at 8,000, and '...the three-zero-zero radial will be for
the VOR approach to Runway One-Two at Dulles, altimeter
two-niner-point-seven-four.' The crew acknowledged. Cockpit voice recordings
(CVR) showed that the VOR was tuned and altimeters properly set."

"At 10:57 the crew again discussed the approach, including Round Hill
intersection, the final approach fix, VASI, runway lights, and the airport
diagram."

"At 11:01 the flight was cleared to 7,000 feet and handed off to Dulles
Approach Control. Dulles cleared it to proceed inbound to Armel VOR and to
expect the VOR/DME approach to Runway 12. At 11:04 the flight reported level
at 7,000, and five seconds later the controller said, 'TWA Five-Fourteen,
you're cleared for a VOR/DME approach to Runway One-Two.' The captain
acknowledged this."

http://www.aopa.org/asf/asfarticles/sp9806.html



If I'm not totally mistaken, ROUND HILL is 11.6 DME from the FAF (which
is in turn 6 DME from AML), not the IAF. I guess ROUND HILL is the
actual IAF?!


Oops. I should have written, "...when they reached ROUND HILL, 11.6 miles
from the FAF. There is no designated IAF on this plate.



Hm. My reading of the old approach plate would be to stay at or above
3300 (which MSA radius was used back then?) until ROUND HILL, then
descend to 1800, and at 6 DME AML (FAF) start descending to MDA.


According to the regulation in effect today, given the clearance TWA514
received, you'd stay at 7,000 until ROUND HILL.



Where did this captain get the idea to descend below the MEA of 1800ft
before the FAF? You said "but decided that clearance for the approach
was clearance to the initial approach altitude" - which would be 1800ft.
Did they overshoot this descend (you mentioned 1670ft), or did he
actually thought he could descend to MDA?


They were descending to 1,800. The weather was bad, the CVR mentions a
downdraft and a bumpy ride. Why the captain chose 1,800 is a mystery. If
you extend the 300 radial beyond ROUND HILL, you can see they'd be flying
almost directly over a 1764' obstruction. The MSA for the quadrant they
were in is 3300'. The MEA for the route from Front Royal VOR, which was
just 14 degrees off of their track, was 3400'. How anyone could examine
that plate and conclude 1800 MSL was a good altitude west of ROUND HILL is a
mystery to me.