Rvr vs ceiling
 

my first post...yahh
I have a interview tomorrow with eagle, and there is this last question i am trying to find an answer for
for take off alternate.

lets say that the RVR is above the required for landing, however the ceiling is below the required. do we need a takeoff alternate?
in some parts of the regs, it almost seems like its the RVR there is ruling only.
I would greatly appreciate some help

thanks

JJ

Unless the approach plate SPECIFICALLY states a ceiling is required (like some mountainous airports, etc), visibility is controlling and ceiling doesn't matter, AS LONG AS YOUR TALKING ABOUT NEEDING A TAKEOFF ALTERNATE. Also, RVR is controlling, as long as the field is equipped as such.

You need a take off alternate anytime the visibility is below the lowest CAT I minimum for a usable approach.

It doesn't really get any easier than that. Sure, the interviewer may say "it's 4000 RVR, but but they're calling it vertical visibility ZERO, you SURE you don't need a take off alternate?" He's usually pressing you to see if you're going to stick to your guns and are sure of the answer.

What he said.

You'll see many times when the ceiling is OVC 001 and the visibility is 1/2 SM ... perfectly legal to shoot the approach... Just might be a little hairy lol

And RVR, when reported, is always controlling. I've seen it where the RVR was 1700 and the reported vis was 1/2 SM... not legal since the RVR requirement was 1800. It's a pain, but it's always controlling by the regs.

Good luck!!

And not to get too wrapped around the axel and confuse the issue. But to the OP asking the question, you'll more than likely have an approach plate being shown to you during this question. MAKE SURE TO READ THE VIS REQUIREMENT FOR THE SPECIFIC PLATE!!!!!! It's a common way to trip up a guy if it's a non standard vis required. Also, there may be notes that say "if ABCD is inop, increase RVR to something above the lowest possible requirement". Make sure to read the notes and pay attention to the what the plate says. So if he says "ABCD is inop and this is the only approach available, do we need a take off alternate?"

Will this happen to you? Probably not, it'll probably be a standard/straighforward ILS at a big airport. But just be careful that you're not being thrown a curve ball. The interview boards know the gouge is out there and shared, sometimes they try to change it up. So look at the plate, make sure you caught all the possible gotcha's, then fire off your answer with confidence.

another thing to consider is required vs. prudent. While it might be legal to NOT list a TO alt., if the wx is right at the ragged edge of being legal, I'd have the conversation with the dispatcher and the co-pilot about potentially adding one. In an interview setting, this is a good opportunity to show you know the regs, AND have ability to use CRM.

Agree 110% with HSLD

Always better to air on the side of safety.

And definitely look at the entire approach plate. They probably won't, but could ask "with the ALS OTS (approach light system out of service) what is the required RVR for the approach? Or it could be with a different altimeter setting from another airport. Most interviews are standard and straight forward, but if you're doing really well they could "test" you to see how much you're paying attention. Not difficult, just make sure you read the whole chart before you answer :-)

Again, agree. Another way they may try to get a guy is to say "we're CAT II capable, the runway has a CAT II approach, and it's a below CAT I but above CAT II, do we need a TO alt?"

To repeat, it ONLY applies to the (applicable) CAT I mins.