If you could change one thing in the Knowledge tests...

... what would it be?

My choice would definitely be to update the Weather Charts. Honestly, in everyday flying & flight planning, I've never EVER seen the ones the FAA uses in their knowledge tests. No doubt most of them were state of the art back in the early 1960's

Not just one.
1. Get rid of the stupid time/distance to VOR based upon radial change questions.
2. Change answers so you are not penalized for being too accurate.

For starters, they could at least update the images that are so badly scanned you cannot read them. I like when test prep companies have to apologize for the unreadable images and put a note in saying "we do this because this is the actual un-readable image you'll get on your test".

Then if they wanted to get really ambitious maybe update the performance questions so that the answers were right.

And, drop the $150 tests at special proctor centers. Everybody already has access to most of the questions anyway if they want to cheat. Make it a secure web site and allow CFI's to proctor their student's tests, they are already granted far more important trust and authority in allowing a student to solo, I think if they can be trusted with that they can be trusted to proctor a written.

And... oh, wait you said "one thing".

Get rid of the knowledge test.

Make the questions relevant.

The tests are $150 a piece???? The last time I took one I paid like $90.........

Get rid of the VOR questions, or at least update them making them more practical.

Drop the $150 charge to.

That's my one.

Aside from the fact that calculating this is has been completely obsolete for years, it's always bugged me that the answer to the question really comes down to:

"If I violate FAR 91.123 and turn 90° away from my cleared route for 10 minutes, I'll find that I would have already been much closer to my destination if I didn't violate the FAR"

Update them to match the current technology. They are all very outdated. The ATP 121 written uses a freakin boeing 727. There aren't that many of them left.

Get rid of the LORAN questions and add some substantial GPS questions. At least with NDB, VOR and old school RNAV, there are aircraft that can and do use them still. LORAN is dead (unfortunately)

-Drop some of the ADF questions in favor of GPS questions and make them relevent (such as the rules regarding GPS use under IFR on the IR written)
-Drop the stupid VOR time/distance questions on the Commercial written and ask scenario based questions on comercial pilot privileges.

Oh, and get rid of that stupid MLS question on the IR written,

What??? The Microwave Landing System is the Wave of the Future. What century areyou living in anyway? [/sarcasm]

Is it even still used? I think the space shuttle used it and it may be around in military ops, but I haven't ever seen a chart for an MLS approach at a civilian airport.

The space shuttle used a variant of the MLS, called the MSBLS--accurate to within 5 centimeters

You'd have to do the same thing if they used a 777. They use an old airplane, but the calculation methodology if you use the paper chart hasn't changed a whole lot.

For the instrument exams, update the charts so that they actually look like NACO charts, not some 40 year old outdated, unused chart format.

You missed my whole point then. The WHOLE test is outdated, not just the performance calculations, etc. When was theblast time you saw a guy/gal wit a fresh ATP in the right seat of a 727 anyways. It would be wise to update the whole test, include RNAV, and put something like most freshly minted ATP's would see, like a CRJ or ERJ on the test. The stiffens have been the same for decades and are outdated. They need some work.

for a glider???

I didn't miss your point, I agree wholeheartedly. You mentioned the 727 as an example, and I just pointed out that a newer plane wouldn't really change the performance questions.