Strategic lateral offset procedure, or SLOP, improves airspace safety.
It increases the lateral separation between aircraft by introducing
a randomness in aircraft lateral position
with respect to route centerline.
States must authorize the use of SLOP
in their aeronautical information publication, or AIP.
Aircraft operators and flight crews should verify
with State's AIP to determine whether SLOP is authorized.
Flight crews operating aircraft with automatic offset tracking
capability can select lateral offsets as an option.
The execution of SLOP is always to the right of route centerline
and never to the left of route centerline.
Offsets to the left of centerline are prohibited.
Avoid using heading mode to offset.
Strategic lateral offsets are authorized to include centerline
and up to two nautical miles right of centerline.
The SLOP options available to an air crew
depend on the capability of the aircraft.
For aircraft capable of offsets in one nautical mile increments
the choices are centerline, one nautical mile right,
or two nautical miles right.
For aircraft capable of offsets in tenths of a nautical mile,
the choices are centerline and any other increment
up to two nautical miles right.
For the correct application of SLOP procedures, consult
the local AIP and or chart supplements for the airspace
which you will be traversing.
One of the main reasons for the recommended use of SLOP
is the high degree of current navigation system accuracy.
Over the years, the increased use of global navigation
satellite systems have significantly increased
aircraft lateral pathkeeping accuracy.
Flight crews should make the choice in SLOP option, which
includes centerline or right offset up to
two nautical miles randomly.
The random selection increases the likelihood
of lateral separation from other aircraft.
The correct application of SLOP helps
mitigate the effect of operational risk.
Operational risk occurs with non-normal events such as
navigation errors, height deviation errors, and
turbulence induced altitude keeping errors.
When an operational error occurs, the likelihood that
another aircraft is at the same cross track position
is reduced with SLOP.
SLOP also allows aircraft to avoid wake turbulence.
The correct application of SLOP can increase the
measured level of safety by 80 percent.
The rules associated with the proper application of SLOP are:
One. Air traffic control or ATC clearance is not required
and it is not necessary that ATC be advised.
Two. SLOP options, including centerline and up to
two nautical miles right of centerline
should be randomly chosen during flight within remote
and oceanic airspace, no matter the routing.
For example, whether organized track, random track,
user preferred route, or published airway, the SLOP
option should be randomly chosen whenever it is authorized.
The choice in the SLOP option can be dynamic throughout
operations, depending on surrounding traffic
and wake turbulence considerations.
Three. Options include route centerline or offset to the
right of route centerline.
There are three choices: either centerline,
one nautical mile right, or two nautical miles right.
Or, if equipped, there are 21 choices:
either centerline, a tenth nautical mile right,
two tenths nautical miles right,
Et cetera, up to two nautical miles right of centerline.
Four. Offsets to the left of route centerline are prohibited.
Avoid using Heading mode to offset.
Choice of centerline or offset up to two nautical miles right
must be randomly selected on every flight by the flight crew.
Do not choose the same option on every flight.
In summary, the correct use of SLOP adds an
additional layer of safety while mitigating
the risk of collision when non-normal events occur
and providing a means to avoid wake turbulence.