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Archive for January, 2008

We had a great question on the forum tonight about shooting the MAP in Aspen, Colorado.

The missed approach procedure for this approach has you turn around and intercept the inbound localizer outbound (the back course of the inbound localizer) I know that when flying a back course inbound, you can set the HSI to the front couse and get normal sensing, but if you are flying outbound on the inbound localizer(the back course outbound, do you set the HSI to the outbound course( 300 on the Aspen missed approach or the inbound of 120 to get normal sensing?) Thanks.

Well, I thought a great way to answer this question would be to show you this approach by flying it!

Thought I would post a recent thread from our forum:

Here was the question that was asked:

Could you please give me a detailed explanation of maximum structural cruising speed. I’m confused as to why it is higher than manuevering speed and doesn’t change with weight like Va does if they both are turbulent air penetration speeds?

Thanks for your help.

And here was the answer:

Hi! Great Question! I actually had to do some “research” for this one!

Va. Known as maneuvering speed. This has to do with the MAX speed at which you can safely stall an airplane. During certification, this has to do with forces measured on the elevator (see image below). Any speed above Va you would exceed structual limits before reaching a stall (not good)

Vno. Maximum structual cruising speed. This has to do with wind gusts measured on the wings. I have to do a little more research but my source told me below the yellow arc it is 20 in. per second gusts and in the yellow arc it is 15 in per second gusts. This has to do with the wings bending and twisting. Not structural limits on the elevator.

Some instructors teach students that Va is turbulent penetration speed which is really not completely accurate and may confuse things. It also may have to do with the fact that Va wasn’t a required certification until the 50’s or 60’s.

Hopefully this helps some.

Instructor.
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Well, keeping with the winter weather theme, I  thought it would be apt to talk about winter notams.   I was checking weather this afternoon for a flight and came across the following NOTAMS:

CLE 12/090 CLE 6L ERD MU 22/26/29 WEF 0712051030
CLE 12/092 CLE 10 ERD MU 39/32/39 WEF 0712051040
CLE 12/115 CLE 24L ERD MU 37/41/38 WEF 0712051421
CLE 12/120 CLE 6L/24R PTCHY THN SN DEICED SOLID WEF 0712051515
CLE 12/122 CLE 24L BOW MU 39/41/38 WEF 0712051515

First of all, what is MU? Prononced “Mew”, MU is a measurement of runway friction as reported by airport managament.  You can tell by looking at the number how slippery and how good your braking will be.

The ERD tells me what type of equipment was used to generate this number:

So ERD would be a Electronic Recording Deceleromter

What you are looking for is a MU value above 40.  The lower the MU, the lower the braking effectiveness.  You can supplement this information with the NOTAMs concerning runway conditions:

CLE 12/120 CLE 6L/24R PTCHY THN SN DEICED SOLID WEF 0712051515

This will give you a full picture of what the runway conditions are and how it will affect your landing performance.