B license exam

[skyboyblue 0]

Yesterday I gave the B license exam (sept 2002 version) and the last question goes like this:

at what altitude does night vision begin to deteriorate? choices were 5,7,9, 11K ft MSL I think. The correct answer is 7k ft.

why is that? I would think night vision can deteriorate at any altitude, especially on the ground around any sort of light?

going to email uspa, and I'll post if no one comes up with a good answer.

[skyboyblue 0]

kudos to jim couch with such a quick response. here's what he said:

One of the first effects of hypoxia is reduced night vision, which can begin to occur at 7000 feet MSL. The reduced vision at higher altitude is due to physiological changes in the body due to reduced oxygen levels. But thanks for pointing out that the question can be stated a bit clearer! We will work on it for the next revision.


sbb

[dterrick 0]

The CSPA manuals are less forgiving in that they state it can begin AS LOW AS 5,000 ft. They further elaborate that "smokers" could have an O2 level of about 5k MSL to begin with. Know anyone who has a smoke just prior to jumping?

This thread also points out the value and importance of taking "several deep breaths" just prior to exit "to supersaturate the blood with O2". While it can't make your vision better, it can make it "less worse". It's also (and more frequently) taught as a relaxation technique early in progression.


Dave

Life is very short and there's no time for fussing and fighting my friend (Lennon/McCartney)

[billvon 2,990]

>This thread also points out the value and importance of
>taking "several deep breaths" just prior to exit "to supersaturate the
>blood with O2".

While this may be a good idea up to a certain altitude, there are two caveats:

-it's easy to hyperventilate at higher altitudes. Hyperventilation causes a lack of CO2 in your blood, and that can lead to dizziness and symptoms similar to hypoxia.

-when you're using in-aircraft oxygen, it's generally better to breathe fairly shallow (i.e. either normal or slower than normal) after you go off oxygen, but before exit. Taking deep breaths after going off O2 can actually _reduce_ your O2 saturation.

Hemoglobin does a pretty remarkable job of transporting oxygen effectively at reduced PPO2 levels, and for most skydivers (i.e. healthy people jumping at or below 15,000 feet, with a relatively fast plane ride) normal breathing works fine.

[quade 4]

Well, for FAA tests (and I'd assume this would also apply to USPA tests) the correct answer is 5,000 MSL.

http://www1.faa.gov/ATpubs/AIM/Chap8/aim0801.html#8-1-6

quade -
The World's Most Boring Skydiver

[ladyskydiver 0]

I took the B license exam and answered 5,000. I got it wrong. The answer sheet says 7,000.

Life is short! Break the rules! Forgive quickly! Kiss slowly! Love truly, Laugh uncontrollably. And never regret anything that made you smile.

[quade 4]

Then I would have to ask what the USPA is using as a reference for this test answer.

Generally speaking any pilot with an FAA license is going to (or should) answer the question 5,000 MSL since the FAA text books are very clear on this point and it's a standard FAA test question.

quade -
The World's Most Boring Skydiver

[skyboyblue 0]

good one quade, I'm on it. be back with an answer shortly...

[quade 4]

Ok, I looked it up in the SIM 6-4 C 1 c 2 and the answer given there is listed as 7,000 MSL.

Interesting.

And now I'm REALY interested in what the USPA is using for a reference especially based on this just below the last item regarding night vision and the on-set of hypoxia . . .

Quote

(3) It takes approximately 30 minutes to recover from the effects of hypoxia.

Actually, a standard demonstration of hypoxic effects is to raise the cabin altitude to 5,000, dim the lights and have the student try to read an aeronautical chart. If the demonstration is going correctly, the student will have a difficult time reading the chart. Then the student is given just a couple of breaths of O2 and within seconds his vision is retored to a state where he can read the chart. It certainly doesn't take 30 minutes for that to happen.

quade -
The World's Most Boring Skydiver

[skyboyblue 0]

way to go quade, now we'll all have to go buy a new SIM AGAIN!! here's jim couch's response:

The 7,000 MSL reference came from a different Internet aviation source, a while ago. The 2003 SIM in Section 6-4 states the 7,000 MSL for the altitude as well. So based on the new information we have found thanks to your link to this website, along with information we found on the American Ophthalmologists Association website, we will be revising the 2004 SIM and tests to reflect the 5,000 MSL altitude. For now we will leave the 2003 SIM and B License test with the 7,000 MSL answer since the SIM is the reference for the test.

The real reason for the test question is to make sure those who will be making night jumps are aware that their vision can be affected at a relatively low altitude above sea level.

Thanks for helping to make sure the information USPA presents is correct!

[quade 4]

Yep. Just got the same note from him as well.

Hey, I'm an old CFI. I absolutely love digging up the "right" answers.

quade -
The World's Most Boring Skydiver

[skyboyblue 0]

we must not be the first to question it then.

allow me to deflate my ego here.

[pilotdave 0]

So the SIM is written based on internet research? Do they have a bibliography at the end? Do they properly cite all their sources? I can't wait until they start doing research from TV and tell us we don't have to breathe in freefall cause our skin will absorb the oxygen.

Dave

[quade 4]

Quote

I can't wait until they start doing research from TV and tell us we don't have to breathe in freefall cause our skin will absorb the oxygen.

Actually, that bit comes directly from the rec.skydiving FAQ Sheet so ya can't blame TV reporters too much if they don't recognize the whuffo sarcasm nature of it.

quade -
The World's Most Boring Skydiver

[cubster 0]

i wonder what the alt. is if your are a smoker?

[quade 4]

It would depend on how recently and how heavily you had smoked.

Basically, you're giving yourself a bit of carbon monoxide (CO) poisoning each time you light one up. CO attaches itself to hemoglobin approximately the same way that O2 would, but then blocks the O2 from attaching. CO takes quite a bit of time to flush itself from the system. It's NOT like a couple of puffs of O2 will magically bring things back to normal.

quade -
The World's Most Boring Skydiver