Bad weather and no glide slope.

[Rocket_Bird]

The ILS is really a luxury when it comes to landing in near zero visibility, low ceilings, and poor weather.

[C]

[quote]The ILS is really a luxury when it comes to landing in near zero visibility, low ceilings, and poor weather.

[-Crossfire-]

A LOC approach does use step down altitudes, just like an NDB, or any other non-precision approach.

[Rocket_Bird]

Thank you!

[Brett_Henderson]

This is gooood stuff (and inspiring me to get busy on the IFR lessons)..

You guys have covered non-precision approaches pretty well.. so there's not much to add... Other than the obvious.. that a non-precision approach would have a higher MDA.. an under real world conditions (if you obey minimums), you catch sight of the runway, well before getting into trouble.

The interesting thing that's rarely talked about, on step-down descents, is that you do not have maintain a constant glide-path. It certainly makes it easier and safer (because it requires a stabilized approach), but as soon as you pass any of the, "descend no lower before" fixes..you can dive to the next altitude, and then fly level, waiting on the next.

The only reason I bring this up, is that in the common IFR training aircraft, you're talking about something pretty small and slow (and forgiving). It's not so much that you end up descending early on purpose, but it's more like a learned response. I'll promise you, that the first time you shoot n NDB approach (if the CFI lets you lern by making a mistake), you'll come in high... VERY high. After a couple of those, you'll find yourself rushing the descent.. and you kinda learn by reward that it's not a bad way to fly the approach (in a FORGIVING, slow airplane). You're not only down to DH sooner.. you get stable there, and the likelyhood of accidentally dropping too low is lessened.

As for no glideslope.. I'd almost rather have a DME. Obvioulsy BOTH would be better.. but of the two.. I've found that chasing a needle is more problematic than just establishing a stabilized approach, and then referencing your agl by DME... because by non-precision minimums, you won't be cutting it that close, anyway.

Today though.. even a lowly, rental C172 is likely to be GPS equiped. GPS approaches take all the "fun" out of it..  Our club has two Warriors, and one Skyhawk with Garmin 430s installed.. and they're all WAAS capable .. pretty much a precision approach for ever runway in the world  8-)

[Rocket_Bird]

Thanks for sharing.  After looking at some of these non-precision plates, I'm starting to see some of the benefits of flying such approaches.  It is quite nice to be able to perform a precision approach, but when it comes down to the above conditions, things do become quite a bit more. . . fun.  :)  Cheers!

[pepper_airborne]

Good reading material here guys, thanks!!

[C]

The interesting thing that's rarely talked about, on step-down descents, is that you do not have maintain a constant glide-path. It certainly makes it easier and safer (because it requires a stabilized approach), but as soon as you pass any of the, "descend no lower before" fixes..you can dive to the next altitude, and then fly level, waiting on the next.

Indeed, although after certain incidents (Iran Air at Birmingham in the UK, trucking it from about 10miles at 700ft!) the word "notional glidepath mandatory" are appearing more and more. Eventually of course, with better and better autopilots, aircraft will just fly a non-precision approach as if it is a precision.

R_B: As you may have noticed, the Loc/Loc-DME procedure is normally on the same plate as the ILS.

[Mobius]

Now also, with the introduction of WAAS enabled GPS systems, you can make an approach into almost any airport with a glideslope.  I think the DA is still higher than an ILS approach though, but I could be mistaken as I've never actually flown a VNAV approach.

[C]

[quote]Now also, with the introduction of WAAS enabled GPS systems, you can make an approach into almost any airport with a glideslope.

[Mobius]

[quote][quote]Now also, with the introduction of WAAS enabled GPS systems, you can make an approach into almost any airport with a glideslope.

[Brett_Henderson]

Wellll.. VORs are obsolete.. have been for years now. The equipment on the ground is a maintanence head-ache..

[-Crossfire-]

[quote]

Today though.. even a lowly, rental C172 is likely to be GPS equiped. GPS approaches take all the "fun" out of it..

[flaminghotsauce]

[quote]This is gooood stuff (and inspiring me to get busy on the IFR lessons)..

You guys have covered non-precision approaches pretty well.. so there's not much to add... Other than the obvious.. that a non-precision approach would have a higher MDA.. an under real world conditions (if you obey minimums), you catch sight of the runway, well before getting into trouble.

The interesting thing that's rarely talked about, on step-down descents, is that you do not have maintain a constant glide-path. It certainly makes it easier and safer (because it requires a stabilized approach), but as soon as you pass any of the, "descend no lower before" fixes..you can dive to the next altitude, and then fly level, waiting on the next.

The only reason I bring this up, is that in the common IFR training aircraft, you're talking about something pretty small and slow (and forgiving). It's not so much that you end up descending early on purpose, but it's more like a learned response. I'll promise you, that the first time you shoot n NDB approach (if the CFI lets you lern by making a mistake), you'll come in high... VERY high. After a couple of those, you'll find yourself rushing the descent.. and you kinda learn by reward that it's not a bad way to fly the approach (in a FORGIVING, slow airplane). You're not only down to DH sooner.. you get stable there, and the likelyhood of accidentally dropping too low is lessened.

As for no glideslope.. I'd almost rather have a DME. Obvioulsy BOTH would be better.. but of the two.. I've found that chasing a needle is more problematic than just establishing a stabilized approach, and then referencing your agl by DME... because by non-precision minimums, you won't be cutting it that close, anyway.

Today though.. even a lowly, rental C172 is likely to be GPS equiped. GPS approaches take all the "fun" out of it..