Had some problems with my camera today...

[Roscue2]

Its a Vivitar Vivicam X327. Not a top of the line camera. Around $80 bucks. Also I'm just in pic. taking for the memories. Wouldn't even call myself an ametuar. Went to an air show today, naturally I tried to take some photos of the planes. Quickly learned some flew way to fast, so I focused on catching them while they taxied down the runway. The problem I had with my camera was that when I had to zoomed in on an object to take the pic., the pic. would become dark or partially dark once taken. Any suggestions on how to stop this from happening in the future??? I eventually realized that I could only zoom in so close before it would become dark. Could this problem have to do with a setting on the camera or is it just because I zoomed in too much?? Thanks in advance.

Here are some pics from today:

 

[TomekV]

I don't know Vivitar Vivicam X327, but I google some about, and I see It is not most complicated camera. So, not many things to mess.
One of possiblity is turned on "Face detection" mode, I saw in other camera, it want to find face in picture, and focus, and exposure on it.
Maybe "face detection" algorithm make mistake and try to correct exposure on front of airplane (one highlighted area - first photo), so whole picture is too dark. When You are zoomed, algorithm see a face not seen in wider angle (too small).
I don't know exactly what is Your settings on, but may it helps.