Grandma's UFO

It one evening while my grandmother was taking her dog for a walk, she had heard a strange noise outside and she couldn't figure what it was? She had happened to looked up into the sky; and there it was! She told me she had seen a strange oval shape object up into the sky. The oval shaped object had stood there for about 20min. then it started to headed out towards the West, and 15 minutes later, the object had headed towards back to my her house flying very low! Low enough where we can see it more up close. It made another sound that went "Bloop Bloop Bloop Bloop Bloop". She had notice that this oval shaped object was heading Northeast, My Grandma had told me that this object started heading towards over by the Glenview Air Naval Airbase. (in which it is now closed down known as of today) My Grandma would not admit that she had seen a UFO, because she's a very religious person, and the only thing that what it could of been was; either an top secret military aircraft or one of "God's Mystery Suprises" that we aren't not to suppose about???...
Date of sighting is approximate.  PD