What is taxi
Taxi is the autonomous ground movement of the aircraft from parking areas to the active runway holding point, and vice versa after landing. It encompasses the entire route between parking and the point at which the controller (TWR) will give take-off clearance.
Taxi is authorized by:
- GROUND at large airports (Zurich, Geneva)
- TOWER at small/medium airports (Lugano, Locarno, Bern)
In both cases, you never taxi without explicit authorization.
Standard structure of a taxi instruction
A typical taxi clearance contains five elements:
- Identification — your callsign
- Destination — "to holding point runway X"
- Route — "via Alpha, Bravo, Charlie 1" (taxiways to follow)
- Any "hold short" — "hold short of runway 28" (stop before an intersecting runway)
- QNH and sometimes runway in use
HB-PMRTaxi to holding point runway 19 via Alpha, QNH 1018, HB-PMR.
HB-PMRTaxi to holding point runway 28 via Bravo, Bravo 1, hold short of runway 32, QNH 1018, HB-PMR.
"Hold short"
The hold short is an instruction to stop before entering a runway or active area. It's absolute: even if the runway looks clear, you don't proceed until TOWER explicitly authorizes you.
The physical hold-short point is the holding point, marked on the ground with:
- Solid and dashed yellow lines (ladder lines) — don't cross without authorization
- Red sign with runway number (e.g. "19-01") — point of no return
- Embedded red lights in the pavement at large airports (stop bar)
"Hold short of runway 32" ≠ "Taxi to runway 32".
- "Hold short of runway 32" = taxi to the 32 holding point and stop there. - "Taxi to runway 32" = proceed toward runway 32 (more precisely, to its holding point — but you can taxi up to it without further authorization).
Mistaking this distinction is the most common cause of runway incursion — one of the most serious events in aviation.
Runway crossing
When taxi requires crossing a non-active runway, you must have explicit authorization. Phraseology:
HB-PMRCross runway 32, taxi via Charlie to holding point runway 28, HB-PMR.
The pilot never assumes authorization to cross a runway. If the taxi clearance doesn't say so explicitly, stop at the holding point and ask.
Ground markings
Knowing the markings is part of the job:
| Marking | Meaning |
|---|---|
| Solid yellow line | Taxiway centerline — follow this line |
| Double solid + dashed yellow line | Holding position (point) for runway |
| Red line with white lines + red sign | Absolute stop — don't cross without clearance |
| Dashed white line | Runway edge |
| Red "NO ENTRY" | Forbidden area — never enter |
| Yellow sign with numbers/letters | Identification of current taxiway |
When the pilot must ask for guidance
At large airports it's easy to get lost taxiing. If you're not sure where you are or where to go, stop and ask. Standard phraseology:
GNDHB-PMR, you are now at Bravo 4, taxi straight ahead 200 metres, then turn right at Bravo 1, continue to holding point runway 28.
HB-PMRRoger, taxi 200 metres straight ahead, right at Bravo 1 to holding point runway 28, HB-PMR.
Asking for "progressive taxi" means: "guide me step by step". The controller will give it gladly — it's preferable to an aircraft accidentally entering an active runway.
Controllers prefer a thousand times a pilot asking for help to one venturing in confusion. Never be ashamed to say "unable to taxi" or "request progressive".
Taxi speed
Standard taxi speed:
- On straight taxiway: 20-25 knots (maximum)
- In turns: 10 knots
- Near parking or busy areas: 5-10 knots
Excessive taxi speed is dangerous due to: - Difficulty steering - Braking on slippery surfaces - Late reaction to ATC instructions
In Switzerland, Skyguide recommends maximum attention on taxiways in winter (frost, packed snow).
Swiss specifics
At Lugano LSZA taxi is simple: a single runway (19/01), few taxiways (Alpha, Bravo). At Locarno LSZL even more direct: almost all aprons feed directly onto the taxiway leading to the runway. On these airfields "progressive taxi" is rare because the geometry is elementary.
At Zurich LSZH instead, taxi is a challenge even for experienced pilots: 4 active runways, dozens of taxiways, complex signage. Study the Zurich diagram before flying there and keep the chart open during taxi.
Summary — to remember
- Never taxi without explicit clearance.
- "Hold short" is absolute — stop at the red sign.
- Runway crossing requires explicit authorization.
- Study the markings before flying at large airports.
- Reduced speed, especially in turns and on slippery surfaces.
- Ask for "progressive taxi" if disoriented — always better.
Sources
- ICAO Doc 4444 — PANS-ATM, Chapter 7
- ICAO Doc 9432 — Manual of Radiotelephony, Chapter 4
- ICAO Annex 14 — Aerodromes (markings and signage)
- AIP Switzerland — AD 2 (for each aerodrome, with taxi diagram)
The wiki gives you the parts. The course teaches you to assemble them.
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