FORD 2013 Flex v.4 - Manual (Page 245)

Zone coverage also decreases when parking at shallow angles. Here, the
left sensor is mostly obstructed; zone coverage on that side is severely
limited.
System Lights and Messages
The BLIS® and CTA systems
illuminate a yellow alert indicator in
the outside mirror on the side of
the vehicle the approaching vehicle
is coming from.
Note: The alert indicator dims when the headlamp switch is not in the
off position and nighttime darkness is detected.
CTA also sounds a series of tones and a message appears in the
information display indicating a vehicle is coming from the right or left.
CTA works with the reverse sensing system which sounds its own series
of tones; see the Parking Aids chapter.
244 Driving Aids
2013 Flex (471)
Owners Guide gf, 4th Printing, December 2012
USA (fus)