ILS OR LOC/DME Approach

[Juliet Lima]

just because your Jeppesen doesn't have it, doesn't mean it isn't there.

conversely,

just because your Jeppesen has it, doesn't mean ATC has it.

go figure!

 

[germb747]

You're absolutely right. For an ILS (ILS only, as written, not "ILS or LOC/DME RWY 5", for example), if there are LOC mins depicted, ATC has to clear you for the ILS since it's the only procedure published. You're free to fly the LOC profile and mins thereafter. However any sidestep or circling would have to be separately cleared.

On this approach, you wouldn't need a separate or specific clearance to fly down to the DME mins, you'd just do it if you have it:

http://204.108.4.16/d-tpp/0903/00074VT30C.PDF

Bonus question for anyone: Why the different holding instructions depicted?

Funny, yesterday I was flying the ILS 15 at KSKF, using the LOC mins. At MDA, tower called us and said "low altitude alert, check altitude immediately", when we advised them that we were doing LOC-only procedures. Is that something we're specifically supposed to tell them, because it's never come up before with them?

 

[tgrayson]

Is that something we're specifically supposed to tell them, because it's never come up before with them?

Controllers say it's helpful for them to know; the MSAW goes off based on your descent rate.

 

[ATCer]

<<Funny, yesterday I was flying the ILS 15 at KSKF, using the LOC mins. At MDA, tower called us and said "low altitude alert, check altitude immediately", when we advised them that we were doing LOC-only procedures. Is that something we're specifically supposed to tell them, because it's never come up before with them?>>

No, we are required to issue that alert when the alarm goes off. Even if you tell us, we are to issue it.

The alarm is set up for certain approach profiles and alarms when aircraft are outside, or projected to be outside those parameters. So, if you duck down to your MDA real early, the alarm will go off. Conversely, if you are on a visual approach and descend late, the alarm will go off as well.

I have never in over 18 years, thankfully, issued a low altitude alert to an aircraft in hard IFR conditions. All of mine have been when it is VFR and the aircraft are clearly visible.

Kind of crazy, but those are the rules.

 

[SteveC]

I have never in over 18 years, thankfully, issued a low altitude alert to an aircraft in hard IFR conditions. All of mine have been when it is VFR and the aircraft are clearly visible.

The first one that I ever received was when I was hard IFR, in a Piper Warrior and a newbie IR pilot, doing a LOC BC approach into PTK. Ceiling was fairly low, not right at minimums, but close. ATC calls up with a low altitude alert, just while I'm already nervous about diving for minimums in actual conditions on a Back Course approach (hoping I remembered how to set up the CDI correctly!). Gave me a bit of a start and a little bit of panic as I tried to figure out what could be wrong, all the while trying to remember to "pull the tail" or whatever that saying was that I'd use to track a BC approach. I quickly arrested my descent rate, checked my altitude, double checked my altitude, corrected my course, triple checked my altitude, queried ATC about the alert, quadruple checked my altitude, then slowly continued on down to minimums, found the field and landed.

I still wasn't sure how close I had come to being a statistic, so I spent some time talking to some more experienced pilots to figure out what happened. Finally decided that it was just my descent rate coupled with a low ground speed that triggered the warning, and that as long as I leveled at MDA like I was supposed to I was fine. ATC wasn't able to give me a reason for the alert while I was flying the approach, in fact I think I even asked them if they showed me too low, and the response (as I remember) was basically "we don't know the reason for the alert, we're just passing it along". That sure didn't help a newbie IR pilot feel any better, but in hindsight it all makes sense.

 

[clestudentpilot]

I have never in over 18 years, thankfully, issued a low altitude alert to an aircraft in hard IFR conditions. All of mine have been when it is VFR and the aircraft are clearly visible.

Kind of crazy, but those are the rules.

I issued one once to an a/c that flew the approach pretty much to minimums. It was a nasty winter day, and there is a step down on the VOR approach, before the first step down , I got it, issued it, and I though the pilot was going to go missed right then and there...he was scared. His altitude indicated 2200, and the MDA in that portion of the approach is 2020, so he was still above that, but the computer projected his decent would take him below the MDA I guess.