Reading LSO Grading

Overview

The LSO (Landing Signal Officer) — the AIRBOSS in DCS — is the person on the deck who watches you come in and decides whether you catch the wires or go around. In GTFO the carrier runs the standard MOOSE AIRBOSS, so the LSO grades every approach the same way a real carrier would, and the results are logged for every pilot.

For every pass the LSO:

1. Contacts you at abeam — on a standard Case I approach you'll hear “Paddles, contact” as you cross abeam.
2. Calls the ball — once you're in the groove the LSO tells you to “Call the ball”, you answer with your ball call (high, low, lined up, etc.), and the LSO answers “Roger ball”.
3. Grades the groove — your position is sampled at fixed evaluation points all the way down the final approach and a grade is assigned for the whole pass.

Think of it as the most opinionated observer in the room: the LSO does not care how the rest of your sortie went. All it cares about is the last two minutes and whether you put the hooks through the wires.

Where in the Groove You're Graded

The approach is sampled at five evaluation steps, measured from the rundown (the end of the trap). You're graded at each one — so an approach that starts off but recovers gets graded on the recovery, and vice versa:

The optimal approach the LSO is looking for is a ~3.5° glideslope with touchdown between the 2nd and 3rd wire. Deck height and wire locations are factored into the math, so the numbers you should be flying stay the same on every carrier.

The Grading Calls

At each step the LSO calls out every deviation it sees, using standard carrier shorthand:

Advisory calls (they appear in the details but don't drive the grade):

“A Little” vs “A Lot”

Every call comes with a qualifier that tells you how bad it was:

• Parentheses — “a little”: (H) means you were a little high. Minor.
• Underline — “a lot”: _H_ means you were a lot high. Major.

So a details string like IM:(LUL) IC:H IC:(F) AR:_LO_ reads as: a little left of line at the middle, a normal high and a little fast in close, and a lot low at the ramp.

The Grade Scale

Once all the calls are in, the pass gets a single grade and a score out of 5.0:

Wave-Off Conditions

Between IC (in close) and AR (at the ramp), the LSO waves you off (technique wave-off) when:

• Lineup error is more than 3.0° to the left or right, and/or
• Glideslope error is below −1.2° (a lot low) or above +1.8° (a lot high), and/or
• Angle of attack is exceeded (only evaluated for TOPGUN-graduate skill level).

Waves can also come from the pattern itself — pattern wave-offs are called for a bad break entry, an early or late break, being out of position at abeam, the ninety, wake issues, or a fouled deck (aircraft on the deck while you're between IM and IC).

Time in the Groove

A clean approach is also a timed approach. The LSO measures how long you spend in the groove and grades it:

If you're consistently fast or slow, the groove grade drags your overall result down — keep an eye on the Tgroove column. (For the AV-8B the reference is different: under ~55 s is fast, ~75 s is okay, over ~76 s is slow.)

Error Thresholds

For reference, here is how the LSO interprets your position (the same table the tool above uses):

Glideslope error (GLE)

Lineup error (LUE)

(±2.0° is where AA / OS start being measured.)

Skill Levels

The AIRBOSS knows what it's grading. Three skill levels adjust how tight the error margins are:

Higher skill level = tighter tolerances and more evaluation (TOPGUN graduates also get AoA evaluated).

The Wires

When you trap, the LSO logs which wires you caught — wires 1 through 4. If the board shows wire 99, you caught none of them: a bolter. Touchdown between the 2nd and 3rd wire is the goal.

Reading Your Results

Your results show up in three places:

1. In sim — F10 → Kneeboard → Results gives you the Greenie Board, “My LSO Grades”, and the last debrief.
2. The results CSV, with one row per pass:

Here's what a couple of rows look like:

Name,Pass,Points Final,Points Pass,Grade,Details,Wire,Tgroove,Case,Wind,Modex,Airframe
GTFO | Pilot Man,3,3.0,3.0,(OK),IM:(LUL) IC:(H) IC:(F),2,16.2,II,12L,444,F-14A
GTFO | Pilot Man,4,5.0,5.0,_OK_,,3,17.1,I,8C,444,F-14A

3. Recovery case — the approach profile depends on the weather: Case I (day, ceiling > 3,000 ft, vis > 5 NM), Case II (day, ceiling > 1,000 ft, vis > 5 NM), and Case III (night or below Case II minimums). Your Case column tells you which profile you were graded against.

Putting It All Together

A quick reference for what the LSO expects from a clean pass:

• Abeam: on speed, lined up with the deck, on time for the break.
• In the groove: call the ball when asked, answer high/low/lineup honestly.
• Glideslope: ~3.5°, stable — no fly-throughs, no crossing back and over.
• Speed: on the approach speed at IC and holding it to the deck.
• Touchdown: between the 2nd and 3rd wire, with the speed right to trap.

Hit all of those and the grade takes care of itself. If your results show calls you don't understand, paste them into the lookup at the top of this page.

For the standard operating procedures behind all of this, see Airfield Operations and Reading RSO Grading for the land-based equivalent.