Flight Phases & Transitions

Every flight Stratos tracks is in one phase at a time: boarding, climb, cruise, landed and so on. Stratos works the phase out by itself from what your simulator reports, with no flight plan or script needed, so it works the same for a booked route and a free flight. This page explains what each phase means and what moves a flight from one to the next. For the bigger picture, see Phases of flight.

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The phases, in order

What Phase shows on a normal flight, from gate to gate:

1. Boarding: parked at the gate (under 2 kt).
2. Push Back: the aircraft starts to move, 2 to 8 kt (a tug push, or the first roll off the stand).
3. Taxi: taxiing out with an engine running, 8 to 45 kt.
4. Take Off: takeoff power set and accelerating past 45 kt.
5. Climb: wheels up, climbing towards cruise.
6. Cruise: levelled off and holding altitude.
7. Descent: top of descent, coming down.
8. Approach: low and near the field (within 50 nm, below 8,000 ft AGL).
9. Final: low and slow near the field, below 1,000 ft AGL and under 210 kt.
10. Landed: wheels down, rolling out.
11. Taxi In: off the runway, taxiing to the gate (8 to 25 kt).
12. Arrived: stopped at the gate with an engine still running.
13. Deboarding: engines off. The flight is done.

Two more phases only appear when something unusual happens: Rejected Take Off (an aborted takeoff roll) and Go Around (a balked landing). There is also unknown, which you won’t normally see. The straight line down the middle is the normal order. The labelled side arrows are the back-steps and recoveries under Unusual situations.

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What you’ll notice in the cockpit

• Climb, cruise and descent lag a few seconds. Stratos waits for a change between them to hold before it accepts it. That’s what stops the phase flapping in turbulence or while the autopilot hunts for an altitude. Touchdown and a go-around show straight away.
• A fast taxi stays in Taxi. Take Off needs takeoff power as well as 45 kt. With the engines at idle, 50 kt on a taxiway is still Taxi.
• A tug push stays in Push Back. Taxi starts at 8 kt once an engine is running, so being towed faster than that with the engines off still counts as Push Back.
• Holding short doesn’t go backwards. The ground phases before departure only move forward: stopping at the hold keeps you in Taxi.
• A step climb shows Climb, then Cruise again. Climb from FL370 to FL380 at a normal rate and the phase goes to Climb, then back to Cruise a few seconds after you level off, with your cruise altitude updated to FL380. Only a slow drift (under about 200 fpm, or less than 300 ft) stays in Cruise the whole way.
• A low arrival can skip Approach. If you’re already below 1,000 ft AGL and under 210 kt when you come within 50 nm of the field (a low VFR hop, say), the flight goes straight from Descent to Final.
• Landed holds for a moment. After touchdown Stratos stays in Landed for at least 1.5 seconds, so your airline’s landing rule fires even on a short, slow rollout.
• Deboarding is the end. Once the engines are off at the gate, the phase doesn’t change again.

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Unusual situations

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Rejected takeoff

If you abort the takeoff roll and slow below 45 kt on the ground, Stratos calls it a Rejected Take Off when it’s sure a real roll was under way: you’d been in Take Off for at least 3 seconds, or you cut the power below half its peak during the roll. Otherwise it was a fast-taxi blip and the phase goes back to Taxi. Once you slow below taxi speed to vacate, it returns to Taxi.

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Go-around

On final, pitch up to 8° or more with 70% N1 or more and Stratos switches to Go Around. From Landed the same applies once you’re above 50 ft AGL and climbing, so a bounce isn’t mistaken for a go-around. When the pitch and power ease off, it moves to Climb if you’re climbing away, or back to Approach if you level off or descend for another try.

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Touch-and-go

After a touchdown (Landed, Taxi In or Arrived), climbing away above 50 ft AGL for the usual few seconds takes the flight back to Take Off. If you’re still pitched up at go-around power when you pass 50 ft, it shows Go Around instead. A bounce on landing doesn’t meet that bar, so a firm arrival isn’t mistaken for a departure.

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Approach recovery

Two ways out of Approach, so a passing reading can’t trap you there:

• Start climbing and it goes back to Climb (a missed approach that doesn’t meet the go-around test).
• Hold level near your recorded cruise altitude for 30 seconds and it goes back to Cruise (for example when an altimeter setting change briefly looked like a descent).

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Moving off from the gate

If you start rolling again after Arrived (you gave way, or were held short), the flight goes back to Taxi In once you’ve held 4 kt or more for 3 seconds. That’s a lower bar than the 8 kt after landing, so a slow marshalled taxi still counts.

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Helicopters, pistons and turbines

The same phases apply to every aircraft, but a few rules adapt:

• Helicopters have no takeoff roll. They pass briefly through Take Off as they lift off (so your airline’s takeoff rule still fires), then go to Climb. They can land straight from Climb or Cruise without Approach or Final. Go-around detection is off for helicopters, because normal flying involves high pitch and power.
• Pistons report no turbine N1 (except in X-Plane, which reports it as RPM percent), so the takeoff power gate uses engine RPM instead.
• Turbines (jets and turboprops) use N1 for takeoff power and go-around detection. Whether an engine counts as running (what moves Arrived on to Deboarding) comes from the simulator’s per-engine on/off flags, not N1.

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How Stratos detects phases

Terms used below

• kt: knots, here ground speed. All speeds on this page are ground speed unless stated otherwise.
• VS / fpm: vertical speed in feet per minute.
• AGL: height above the ground directly below you, not above sea level.
• N1: how fast a jet or turboprop’s main spool turns, as a percentage. Stratos uses it as a stand-in for the power you’ve set.
• RPM %: the piston equivalent of N1, as a percentage of maximum engine RPM.
• nm: nautical miles, here the distance still to fly to the arrival airport.

It samples, then looks at trends. Stratos takes a snapshot of your flight data about twice a second and keeps the last five seconds. Decisions use the averages over that window, so a single altitude spike or bad vertical speed reading doesn’t move the phase. It waits for reliable data. Until the window holds at least three samples (about a second), the phase stays put. That stops bad readings at sim start-up from jumping it around. Climb and descent are trends. Vertical speed and altitude have to agree, so changing the altimeter setting (which shifts indicated altitude at once while VS stays near zero) isn’t read as a climb or descent. Changes are confirmed, not instant. A change between climb and descent must hold for 3 seconds and move altitude by at least 50 ft. Leaving cruise needs 3 seconds and 300 ft, a higher bar so a bumpy ride doesn’t knock you out of it. The on-ground flag is read every frame. Simulators often flicker it for one frame at rotation or on a firm landing, so Stratos guards against it: once you’re in Climb or Cruise, a stray “on ground” frame is ignored, and the phases after touchdown ignore a moment back in the air. What it reads from the simulator: Stratos works out your cruise altitude from sustained level flight rather than reading it from a flight plan. At higher simulation rates the altitude gates scale up, so autopilot wobble under time compression doesn’t bounce the phase.

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Phase reference

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Departure

Takeoff power is N1 of 50% or more on a turbine, or RPM of 70% or more on a piston (except in X-Plane, where piston RPM is read as N1).

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Airborne

• Cruise altitude is rounded to the nearest 100 ft, and updates each time you level off after a climb or descent.
• Cruise needs at least 500 ft AGL, so a brief level-off just after a low go-around stays in Climb or Descent and still reaches the runway the normal way.
• Approach and final are kept near the arrival airport, so a light aircraft cruising low over high terrain isn’t mistaken for one on approach. With no arrival airport (free flight), only the height above ground is used.

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Arrival

Every threshold in one place

Departure

What	Threshold
Push back	2 to 8 kt
Taxi	From 8 kt with an engine running
Takeoff	45 kt or more
Takeoff power, turbine	N1 of 50% or more
Takeoff power, piston	RPM of 70% or more
Takeoff held after an early liftoff	2 s

In the air

What	Threshold
Climbing	Average VS above +200 fpm
Descending	Average VS below −200 fpm
Level, for cruise	Average VS within ±100 fpm
Cruise	About 3 s level, within 300 ft, at least 500 ft AGL
Leaving cruise	3 s sustained and 300 ft
Switching between climb and descent	3 s sustained and 50 ft
Approach	Within 50 nm, below 8,000 ft AGL
Final	Below 1,000 ft AGL and under 210 kt, within 50 nm or in a landing configuration

Arrival

What	Threshold
Landed hold	At least 1.5 s
Taxi in	8 to 25 kt
Arrived, engines running	Under 2 kt for 3 s
Arrived, engines reading off	Stopped 10 s within 5 nm, or 60 s further away
Moving off from the gate	4 kt or more for 3 s
Landed after a misread touchdown	On the ground under 45 kt for 5 s

Special transitions

What	Threshold
Rejected takeoff	3 s or more in takeoff, or power below 50% of peak
Go-around	Pitch 8° or more and N1 70% or more, from final (or from landed above 50 ft AGL and climbing)
Touch-and-go	Above 50 ft AGL, climbing, sustained
Approach back to cruise	30 s level near cruise altitude

Detection

What	Threshold
Sampling	About every 0.5 s over a 5 s window
Reliable data	3 samples (about 1 s)

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For VA owners

The phase drives several things your airline sets up:

• Event rules. Many rules are tied to a phase, such as “Phase Take Off” or “Phase Landed”, and fire when the flight reaches it. See Event rules.
• Additional fields. You choose which extra fields ride along on position reports during each phase (winds during climb, cruise and descent, for example). See Additional fields.
• Block and air time. The phase changes mark when the aircraft starts moving, leaves the ground, touches down and parks, which is how block time and air time are worked out.
• The phase field. Every position report carries the current phase in capitals (BOARDING, CLIMB, CRUISE and so on), with TAXI_IN and ARRIVED both sent as TAXI_TO_GATE. While the sim is paused it reports PAUSED, and the underlying phase is kept for choosing additional fields. See The phase fields.
• Plugins read the live phase through the useFlightPhase hook, which updates only when the phase changes.

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Related pages

• The tracking screen
• Pauses and disconnects
• Diversions and tech stops