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View Full Version : LDA with straight in minimums?


weekendflyer
08-06-2011, 12:12 PM
Pretty much referring to the ROSSLYN LDA in to DCA. Why does the chart still have straight in minimums if its considered a circle app? As far as I know, more than 30 degrees is considered circling...


ASpilot2be
08-06-2011, 12:26 PM
My guess is that because the approach is to a specific runway it has straight in minima published. But the minimums are the same as circling.

I would be curious to know this also.

galaxy flyer
08-06-2011, 01:42 PM
Unless there is an obscure TERPS Manual exception, the only explanation I can give is that IT'S KDCA AND THE FAA CAN DO WHAT WANTS. The LDA 19 is outside of 30 degrees, as is the ROSSLYN, the course does cross the extended centerline but the ROSSLYN doesn't; the descent gradient is less than 400 ft/nm. They both should be circling only because of the course guidance outside of 30 degrees of runway centerline.

GF


ASpilot2be
08-06-2011, 02:23 PM
Here are some more examples that makes me think my original theory might be correct:
LDA-H has no straight in.
http://www.airnav.com/depart?http://204.108.4.16/d-tpp/1108/06213LDADH.PDF
LDA/DME RWY11 has straight it.
http://www.airnav.com/depart?http://204.108.4.16/d-tpp/1108/05414LDAD11.PDF

snippercr
08-06-2011, 03:03 PM
Why the heck is it called ROSSLYN LDA? I thought if there were two (or more) approaches to the same runway with the same nav equipment they just named the Z, Y, X etc.

galaxy flyer
08-06-2011, 03:39 PM
ASpilt2be

The Valdez approach is a circle because the gradient on final is greater than 400 ft/nm, where the gradient is less than that at Juneau.

GF

ASpilot2be
08-06-2011, 03:42 PM
ASpilt2be

The Valdez approach is a circle because the gradient on final is greater than 400 ft/nm, where the gradient is less than that at Juneau.

GF
Interesting. Thanks.

I just got the IR the other day, so I am still learning these things. :)

weekendflyer
08-06-2011, 07:01 PM
Unless there is an obscure TERPS Manual exception, the only explanation I can give is that IT'S KDCA AND THE FAA CAN DO WHAT WANTS. The LDA 19 is outside of 30 degrees, as is the ROSSLYN, the course does cross the extended centerline but the ROSSLYN doesn't; the descent gradient is less than 400 ft/nm. They both should be circling only because of the course guidance outside of 30 degrees of runway centerline.

GF

Thanks for the info..

Kenny
08-06-2011, 11:06 PM
It's been a very long time since I had to think about this but I seem to remember from my cfi days that for an approach to have straight in mins it had to satisfy 3 requirements;

A "normal" or approx 3 degree final approach angle.

The final approach path had to cross the approach end of the designated runway..

Final approach course within 30 dgrees of the runway center line.

I think it was somewhere in the Terps.

Premierdriver
08-07-2011, 08:04 PM
The localizer is on the naval airbase across the river...that might have something to do with it?

WANNABE
08-08-2011, 05:49 AM
"lda front course bearing is greater than 30 from runway bearing. Waiver approved 02/06/1985"

WANNABE
08-08-2011, 05:59 AM
different facilities . . different frequencies

WANNABE
08-08-2011, 06:02 AM
Why the heck is it called ROSSLYN LDA? I thought if there were two (or more) approaches to the same runway with the same nav equipment they just named the Z, Y, X etc.

Sorry

different facility. . . . different frequency

Rustee
08-08-2011, 06:11 AM
The addition of a visual approach segment (ref the ROSSLYN LDA approach plate) allows them to waive the 30-degree requirement and publish straight-in minimums.

Sniper
08-10-2011, 01:14 PM
Go here (http://www.terps.com/ifrr/may98.pdf) to read it.

Written by Wally Roberts, former Chair of the ALPA TERP's Committee. It's a touch dated (from 1995, back when it was the 'LDA 18'), but still accurate.

Essentially, the LDA 19 into DCA is created expressly to get non-circling rated airline jet pilots to land visually at an airport when the ceiling is too low to really be doing this safely.

Good discussion of the Canarsie 'follow the lead-in lights on top of the hotel till you see the airport' visual into 13 too.