B a ro - C o r r e c t e d  Pressure altitude-corrected local barometric pressure. 
Altitude 
BCD  Binary Coded Decimal. A coding system in which 
each digit from 0 to 9 is represented by a four bit 
binary number. 
B CRS  Back Course 
BCS  Block Check Sequence. BCS is a cyclic code that is 
used as reference bits in an error detection process. 
BDI  Bearing Distance Indicator 
BDS  Comm-B Designation Subfield 
Beam Width  The beam width is the width of the beam as mea-
sured at the half-power points of the radiated signal 
(WXR). 
Bearing  The direction of a point or navigational aid measured 
clockwise from a reference through 360°. 
BER  Bite Error Rate 
BFE  Buyer Furnished Equipment 
BFO  Beat Frequency Oscillator. An oscillator that produces 
a signal to be mixed with the received frequency to 
produce an audible beat note, for the purpose of 
decoding the Morse code identifier of an NDB. The 
oscillator produces frequencies equal to the sum and 
difference of the combined frequencies. 
BGI  Bus Grant Inhibit. A term used in CAPS transfer bus 
processing. 
BI  Burn-in 
Binary  Base-2 counting system. Numbers include 0,1. 
BIST  Built-in Self Test