What TOWER does
The TOWER (Aerodrome Control Tower) is the ATC unit responsible for traffic control within the Control Zone (CTR) of a controlled airport. Its competencies are three, in geographic order:
- Active runway — clearances for take-off, landing, crossing, and backtrack
- CTR airspace — separation between aircraft flying in the traffic area
- Ground movements in maneuvering areas — when there's no separate Ground control
The TOWER doesn't control what happens outside the CTR or in non-operational airport areas. At large airports (Zurich, Geneva), ground movement is handled by a separate control called GROUND.
The name "tower" comes literally from the physical control tower, the elevated building from which controllers see the airport. Even today the basic principle of tower control is visual control — the controller looks with their own eyes at what's happening.
When you call TOWER
In a VFR flight to a controlled airport, you call TOWER:
- For taxi and take-off clearance (at airports without separate ground)
- For CTR entry clearance (if arriving from outside)
- For traffic pattern (downwind, base, final)
- For landing authorization
- For CTR transit (cleared to cross controlled airspace)
At airports with separate GROUND, the early phases (taxi and clearance) are with GROUND, and you switch to TOWER only when reaching the active runway holding point.
Typical phraseology
First call
TWRHB-PMR, Lugano Tower.
HB-PMRHB-PMR, Cessna 172, parking position Alpha 3, request taxi for VFR departure to Locarno via Magadino, with information Bravo.
TWRHB-PMR, taxi to holding point runway 19 via Alpha, QNH 1018, runway 19 in use.
Take-off
TWRHB-PMR, runway 19, cleared for take-off, wind 200 degrees 6 knots.
HB-PMRCleared for take-off runway 19, HB-PMR.
Entry into CTR for landing
TWRHB-PMR, Lugano Tower, pass your message.
HB-PMRHB-PMR, Cessna 172, position Mendrisio, altitude two thousand feet, two POB, fuel one hour, request right downwind runway 19, with information Charlie.
TWRHB-PMR, cleared to enter CTR, join right downwind runway 19, QNH 1018, report on downwind.
What is NOT in TOWER's competence
To avoid out-of-scope requests, useful to know what the tower cannot give you:
- Radar vectors (radar vectoring) — APPROACH's competence
- IFR departure clearances en-route — APPROACH/Center competence
- Detailed weather information for distant areas — ask INFORMATION or check SIGMET/AIRMET
- FIS service outside the CTR — INFORMATION's competence
- Coordination with adjacent FIRs in flight — handled automatically at frequency change
Asking TOWER for weather info for a destination 50 km away. The tower knows local weather (local CAVOK, wind, QNH). For en-route weather, ATIS, VOLMET, and FIS exist.
TOWER and VFR traffic patterns
At controlled airports, the traffic pattern is managed by the tower. They'll tell you:
- Which pattern: standard left (left-hand) or opposite right (right-hand)
- Where to enter: downwind, base, final, overhead
- When to report: typically downwind and final
- Any extensions: "extend downwind" if there are other aircraft ahead
TWRHB-PMR, number two behind Cessna on base, report final.
HB-PMRNumber two, report final, HB-PMR.
TOWER vs information: who knows what
| Question | TOWER | INFORMATION (FIS) |
|---|---|---|
| Local QNH | ✅ | ✅ (regional) |
| Wind at field | ✅ | ❌ |
| Runway in use | ✅ | ❌ (see ATIS) |
| Traffic in CTR | ✅ | ❌ |
| Traffic outside CTR | ❌ | ✅ |
| En-route weather | ❌ | ✅ |
| NOTAMs | ✅ (local) | ✅ (regional) |
Swiss specifics
In Switzerland all towers are operated by Skyguide. Tower frequencies of main VFR fields:
- Lugano LSZA: 119.000 - Locarno LSZL: 124.875 (Locarno Tower / AERO LOCARNO) - Bern LSZB: 121.875 - Zurich LSZH: 118.100 (TWR North) / 124.075 (TWR South) - Geneva LSGG: 118.700
At Lugano and Locarno VFR is particularly lively: expect precise closing hours (Lugano CTR active only during AIP hours) and special procedures for mixed VFR/IFR traffic.
Summary — to remember
- TOWER controls the CTR: runway, traffic area, ground in some cases.
- You call for taxi, take-off, landing, CTR transit.
- Doesn't give radar vectors — that's APPROACH.
- Knows only local weather — for en-route, FIS or ATIS.
- Manages the traffic pattern at controlled VFR airports.
- In Switzerland it's always Skyguide.
Sources
- ICAO Doc 4444 — PANS-ATM, Chapter 7 (Procedures for Aerodrome Control Service)
- ICAO Annex 11 — Air Traffic Services
- AIP Switzerland — AD 2 sections, frequencies and tower procedures
- Aero Locarno · Subject 090 — VFR Communications (EASA syllabus)
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