Precautionary Landing

A precautionary landing is a deliberate, planned landing away from an aerodrome — a response to a developing hazard before it becomes critical.

It differs from:

Forced landing — landing is mandatory, immediate, because of engine failure or another critical fault.
Normal off-airport landing — planned landing on a non-aerodrome surface (e.g. agricultural flying, gliding).

When is a precautionary landing indicated?

Classic triggers:

1. Deteriorating weather

Visibility drops below VMC minima → IMC risk.
Cloud base sinks → CFIT risk.
Strong wind, turbulence beyond normal operating range.
Thunderstorm approaches → no safe route remains.

Action: land at the closest reachable aerodrome or a suitable field.

2. Fuel running low

Burn higher than planned (stronger headwind, higher consumption),
No fuel at destination (closed, ATC says "no fuel"),
Reserve critical (FRA < 30 min).

Action: land at the next aerodrome immediately, before reserves are exhausted. Better to refuel 50 NM short than be 1 NM short.

3. Technical issue developing

Oil consumption too high (gauge dropping),
Engine temperature too high (CHT/EGT/oil temp),
Unusual vibration,
Electrical system showing problems (ammeter negative, alternator light),
Control issues (trim not working correctly).

Action: land before the issue becomes a complete failure.

4. Pilot or passenger becomes ill

Pilot feels unwell (hypoxia suspicion, nausea),
Passenger needs medical attention,
Stomach issue with pilot (e.g. after a meal).

Action: immediate landing at a suitable aerodrome with medical services.

5. Darkness approaching

Sunset earlier than planned, pilot without night rating.
Rule of thumb: 30-minute reserve before twilight.

Action: land at a day aerodrome before it's too late.

6. Spatial disorientation

Pilot is lost in a valley, unsure of position.
Cloud/terrain uncertainty.

Action: halt at a reachable aerodrome, confirm position.

Preparing for a precautionary landing

Phase 1: make the decision

ADM (Aeronautical Decision Making) — see Decision-Making Models: DECIDE and FORDEC:

Apply DECIDE / FORDEC.
Overcome continuation bias — "only 30 NM left" is not a strategy.

Pilot's authority (Part-NCO.GEN.105):

The PIC holds full decision authority.
A precautionary landing is not weakness but a professional decision.

Phase 2: find a suitable site

Preferred:

Commercial airport with rescue services,
Regular GA aerodrome,
Emergency landing site (off-airport landing field, glider site),
Suitable field (see Engine failure in cruise for field selection).

Field selection criteria:

Adequate length (300+ m for solid, more for PPL depending on type),
Level, no furrows,
Dry, firm,
No livestock, no people, no posts,
Approach into the wind.

Phase 3: inform

Radio:

PAN-PAN if urgent (fuel alarm, technical issue),
MAYDAY if acute danger,
Inform FIS or tower of your intentions.

Transponder:

Squawk 7700 in emergency.
Squawk 7600 on radio failure.

Phase 4: fly the approach

Like a normal approach:

Safe speed (1.3 × Vs),
Flaps appropriate to the surface,
Slip method for short fields/runways without flap extension,
Last 200 ft AGL: between slip terminated and stabilised.

Phase 5: after landing

Shut down the engine (except in special situations),
Fuel cutoffs if fire suspected,
Radio ATC about landing (if possible),
Emergency numbers for help (RCC, police, fire).

Legal aspects

EU law:

Part-NCO.GEN.105 — pilot's authority and duty of care.
Regulation (EU) 996/2010 — investigation of occurrences.
Regulation (EU) 376/2014 — occurrence reporting.

Germany:

Off-airport landing must be reported to BFU/police on damage or special circumstances.
For private meadows/fields: notify the owner; possible damage compensation for crops.

Important: a safe precautionary landing is not an offence — prosecution only follows gross violations (e.g. flying without authorisation, under alcohol).

Maxims

"Better to be down here wishing you were up there than up there wishing you were down here."

"The two most useless things in aviation are runway behind you and altitude above you — until you need them." → Better to land too early than too late.

"When in doubt, land." → If in doubt: get on the ground.