LDA Approaches

[ASpilot2be]

I am curious as to how LDA(Localizer Displaced Approach) works. Do they break off an approach to land? I know JNU has one, where the pilots fly through the cut, make a right hand turn and land. I am curious how this all works.

[AJ]

Hi Alec, although I've never flown one we have lots of photos of aircraft breaking off an 'LDA' approach...turning at the checkerboard at Kai Tak!

[ASpilot2be]

So basically it is an approach to a runway at an angle, then they break off and straighten out and land?

[screaming_emu]

yup alec, an LDA is pretty much like an ILS, but not all of them (I would say a majority) dont have a glideslope attatched to them. Also, the main difference between an LDA approach is that it isn't lined up with the runway. Once the pilots hit the missed approach point (which in this case is at 2 miles from the localizer antenna), if they dont see the runway/approach lighting, they have to go missed.

http://204.108.4.16/d-tpp/0602/01191LDA1_8.PDF

That's the one you were talkin bout. Instead of using a glideslope for descent info, at certain distances from the airport you can descend a little more. As you can see, compared to an ILS, the landing minimums are considerably higher. For your average ILS, minimums are going to be 1/2 mile and 200ft. Here they are 2,200ft and 4 miles. This is because the approach is a lot less accurate without a glideslope (and not being aligned with the runway) so it is termed a non-precision approach.