I was driving back to base when I spotted a white light hovering over the runway.

I was driving back from Eagle Pass, Tx to Laughlin AFB, TX and at that hour, the back gate was closed and one had to drive into Del Rio and turn around to hwy 90 to go to the front gate. 
As I drove towards the base I saw a light over the runway and it just hovered there.  I could see no other lights, just a bright white light.  I had always wanted to see a UFO so was really quite excited. 
I was about 5 miles from the base when it took off and came over my car and headed into Mexico in nothing flat.  I had managed to stick my head out the driver door and could only see a vague shape, but definitley oval shaped.  
It was huge and it was so quiet and so fast. 
It was out of sight in an instant.   
I asked the airman at the gate if he had seen something, but when I drove up, he had been on the phone laughing and giggling and he had been facing towards the front, while the runway was behind him.  
My husband poopooed the notion, but later that week a small story appeared of ufo sightings in Mexico.  
I hope it was a UFO.
Witness indicates that the date of the sighting is approximate.  We have assigned an arbitrary date above, which places the incident in "the late '70's."  PD