The FOIA is limited in many ways and trying to obtain documents pertaining to the UFO is very difficult. I am sure there are certain files that the FOIA will not even be able to get close to enable declassification to even be considered or acknowledged.
The burden of proof is on the requester, firstly to identify the documents to a specific degree in the vast collections of information and documentation in the governments archives and databases; secondly to identify whom would have the documents in a specific department and agency; thirdly the cost of such a search which may or may not provide any releasable documents or any documents whatsoever.
There are also the usual bureaucratic procedures and time delays that usual occur during the processing of some requests. Some take years to process, which may be the result of the declassification of some of the documents, since some maybe time sensitive, or the fact that some agencies use it as a ploy. Certain release authorities have the means and techniques to circumvent the Act and avoid any release or admission of documents or information under the Act.
There is a self generated flaw in trying to obtain documents through the FOIA on the UFO, and that is many researchers who use the FOIA will not cooperate with each other for the greater good. In some cases UFO documents have been found and released to one requester who has not made it known to others, which may contain a piece of information which joins the dots if others share what they have obtained. But alas the nature of UFO research is dismal. The hype that goes with the UFO subject is not in many cases beneficial for the authorities to been able to release documents since this causes unnecessary media attention and grief for them, with questions which some may not want to answer, thus nothing gets released for decades.
I’m sure there exists, if fact I know, since I am in the process of identifying the documents on the UFO subject which can be released, including more documents on the famous Iran UFO encounter of 1976, UTRs from NORAD, and the well known Estimate of the Situation mentioned by Captain Edward J. Ruppelt in his book Report on UFOs, and many more which are not known to the UFO community in general. You will find once a batch of UFO material is released there is not much more disclosure until a long period of time as past. This is mainly to do with the public’s ability as a whole to absorb the type of information which is released and is somewhat expectable to the mainstream without provoking a serious reaction towards those agencies and departments, which they can well do without.
I have decided to continue to use the FOIA for one more year then I will give it a break for some time. Since there is a serious lack of serious research in the UFO community as a whole, and many are not really doing much in this field of investigation.