Commands to add aircraft to the session:  
add rules weight engine runway distance [type] Adds aircraft on final for the specified runway.
add rules weight engine @space [type] Adds aircraft at the specified parking space.
add rules weight engine -bearing distance altitude [type] Adds aircraft on the specified bearing from the field.
Commands for aircraft on the ground:  
taxi taxi-path [hold-short-list] Issues taxi instructions.
hold Aircraft holds current position.
res Aircraft resumes taxi.
cross runway/taxiway Aircraft continues across runway/taxiway that it's holding short of.
cto [heading] Clears aircraft for takeoff on specified heading, or runway heading if omitted.
ctoc Cancels takeoff clearance.
ctomlt Clears aircraft for takeoff. Aircraft will enter left traffic.
ctomrt Clears aircraft for takeoff. Aircraft will enter right traffic.
pos Aircraft will position and hold.
hs Cancels position and hold instruction.
ctopp [heading] Clears a helo for takeoff from present position with optional departure heading.
land Helo will land at present position or at the specified parking space.
nostop Instructs aircraft to NOT hold position when clear of the landing runway, if given taxi instructions during the landing roll.
Commands for aircraft in the air:  
fh heading Aircraft will turn to specified heading, using the shortest turn direction.
tr heading Aircraft will turn right to the specified heading.
tl heading Aircraft will turn left to the specified heading.
fph Aircraft will stop turning and fly present heading.
cm altitude Aircraft will climb/descend to the specified altitude in feet.
spd speed Aircraft will accelerate or decelerate to the specified speed in knots.
erc runway Aircraft will enter a right crosswind for the specified runway.
erd runway Aircraft will enter a right downwind for the specified runway.
erb runway Aircraft will enter a right base for the specified runway.
elc runway Aircraft will enter a left crosswind for the specified runway.
eld runway Aircraft will enter a left downwind for the specified runway.
elb runway Aircraft will enter a left base for the specified runway.
ef runway Aircraft will enter final for the specified runway.
Commands for aircraft in the pattern or arriving:  
tg Aircraft will perform a touch-and-go.
sg [seconds] Aircraft will perform a stop-and-go, stopping for the specified number of seconds, otherwise waiting for a "go" command.
la Aircraft will make a low approach.
fs Aircraft will make a full stop.
go Commands aircraft to start its takeoff roll when stopped on the runway during a stop-and-go operation.
ext Aircraft will extend its current pattern leg until told to turn to the next leg.
ga Aircraft will go around.
mlt Alters pattern direction for left turns.
mrt Alters pattern direction for right turns.
msa Aircraft will make a short approach.
mna Cancels short approach instruction.
ps size Alters pattern size. Fractional values ok. Value is in NM.
tc Aircraft will turn crosswind.
td Aircraft will turn downwind.
tb Aircraft will turn base.
er Aircraft will exit to the right (if possible) when landing.
el Aircraft will exit to the left (if possible) when landing.
lahso runway Aircraft will land and hold short of the specified runway.
ml3 Aircraft will make a left 360.
mr3 Aircraft will make a right 360.
m2 Aircraft will make a 270 degree turn instead of the normal 90 degree turn when turning to the next leg of the pattern.
no270 Cancels an instruction to make a 270 degree turn to the next pattern leg.
mls [# of turns] Aircraft will make an s-turn starting to the left. Use "mrs" for an s-turn starting to the right.
Miscellaneous commands:  
p Pauses the sim.
un Unpauses the sim.
del Deletes the currently selected aircraft.
id Aircraft will squawk ident.
sq code Aircraft will squawk the specified code.
sqi code Aircraft will squawk the specified code and ident.
sn Aircraft will squawk normal. (Mode Charlie)
ss Aircraft will squawk standby.
remarks text Sets flight plan remarks.
fp type altitude route Creates new IFR flight plan.
vp type altitude route Creates new VFR flight plan.
ops Shows stats on arrivals and departures.
Debugging commands:  
fhn heading Aircraft will fly the specified heading instantly, instead of making a realistic turn to the new heading.
sln speed Aircraft will fly the specified speed instantly, instead of gradually accelerating or decelerating to that speed.