On some air bases the Air Force is on one

side of the field and civilian aircraft use the other side of the
field,
with the control tower in the middle.

One day the tower
received a call from an aircraft asking, “What time
is
it?”

The tower responded, “Who is calling?”

The aircraft replied,
“What difference does it make?”

The tower replied, “It makes a lot
of difference. If it is an American
Airlines flight, it is 3
o’clock. If it is an Air Force plane, it is
1500 hours. If it is a Navy
aircraft, it is 6 bells. If it is an Army
aircraft, the big hand is
on the 12 and the little hand is on the 3. If
it is a Marine Corps
aircraft, it’s Thursday afternoon.”