Engine failure in cruise

Engine Failure in Cruise

In cruise you have more altitude and time than on take-off — a restart attempt is possible, and emergency-field selection can be done calmly.

Source: POH (binding), FAA-H-8083-3B Chapter 17.

Immediate actions ("Aviate, Navigate, Communicate")

1. AVIATE — stabilise the aircraft

• Nose down to Vbg (best glide speed) — POH (C172: 65 KIAS).
• Trim for Vbg, hands free for restart attempt.
• Altitude and heading maintained toward emergency landing site.

2. NAVIGATE — pick a landing site

• Direct landing site identified within glide.
• Fields, meadows, railways preferred over forests/water/city.
• Wind considered — preferably land into wind.

3. COMMUNICATE — distress call

• Mayday on current frequency or 121.5 MHz.
• Squawk 7700.
• "Mayday Mayday Mayday, callsign, engine failure, position, X NM SW of Y, altitude, intentions, persons on board."

Restart attempt

During glide (parallel to navigate):

Cessna 172 standard restart procedure (POH-specific):

1. Fuel selector: BOTH (or other tank if one is empty).
2. Mixture: RICH.
3. Throttle: ½ open.
4. Carb heat: ON.
5. Magnetos: BOTH (or test individually).
6. Primer: locked.
7. Starter: crank 5–10 sec.

If no restart: stop after 1–2 attempts, focus on emergency landing.

Special warning signs in cruise

Oil pressure drops to 0 + oil temperature rises

Classic symptom pair for severe oil loss (leak, pump failure, mechanical damage). When both appear simultaneously:

• Prepare immediate emergency landing — the engine will seize or catch fire within minutes.
• Fly to the nearest suitable airport or emergency landing site.
• Declare mayday.
• No further cruise searching for a "better" field.

Oil on windscreen

When the windscreen suddenly becomes covered with oil (typically a ruptured oil line or exhaust-manifold defect):

• Monitor oil pressure and temperature at once — if still normal, the engine remains operable.
• Land at the next suitable airport.
• Be prepared for an emergency landing — the engine may quit at any moment.
• Use side windows or peripheral vision for the approach if the windscreen is fully opaque.

Loud, hammering noise + heavy vibrations

A sudden loud, hammering engine noise combined with heavy vibrations is a clear indication of mechanical engine damage (e.g. broken cylinder head, conrod failure, crankshaft damage):

• Reduce power immediately (throttle back) — minimise further damage.
• Conduct an immediate emergency landing — the engine may quit fully or catch fire at any moment.
• Mayday, squawk 7700.

Tachometer failure in cruise

If the RPM indicator fails during a cross-country flight, but the engine continues to run normally:

• Continue with unchanged power setting to the next suitable airport.
• Have the defect fixed at a maintenance facility — do not continue the flight without the indication.
• This is not an emergency — but a snag that must be entered in the logbook.

Fuel insufficient to reach destination

If the pilot notices during the flight that fuel is not sufficient to reach the destination:

• Perform a safety landing at the nearest suitable airfield in due time.
• Do not continue and hope it will be enough — fuel exhaustion is an avoidable pilot-responsibility emergency.
• Source: typical NTSB statistics name fuel exhaustion as a top cause of engine failure.

Glide performance — key values

• Vbg (best glide speed): POH (C172: 65 KIAS).
• Glide ratio (typical GA): 8
  to 10
  .
• Sink rate at Vbg: typically 600–800 fpm.

Example C172: 5000 ft AGL → glide range ≈ 5000/6076 NM × 9 ≈ 7.4 NM.

Emergency field — 6 S's (see lesson "Engine fire in flight")

Size, Slope, Surface, Surroundings, Sun, Spectators.

Off-field landing — terrain principles

When no runway is reachable, the pilot must select off-field terrain. The following rules come from official sources (FAA-H-8083-3B Ch. 17, AOPA Emergency Landings):

Best terrain choice

• A harvested (mown) cornfield or stubble field is generally best suited for an off-field landing: even ground, few obstacles, hard surface, no vegetation.
• Harvested fields generally preferred over meadows (mounds, mole hills).
• Long-grass meadows are risky — hidden obstacles.

Slope

• An off-field landing on a slope is performed upslope — regardless of wind direction.
• Reason: an upslope approach uses the slope to decelerate; downslope accelerates the aircraft uncontrollably after touchdown.
• Steeply inclined off-field strip: approach with increased approach speed — more energy to absorb sink rate during the flare against the slope.

High vegetation (forest, dense brush)

• For an emergency landing in terrain with high vegetation (forest, dense brush): assume the top of the vegetation is the ground — at that height touch down with minimum speed.
• → Vstall + 5 KIAS with nose high, full flaps.
• Result: aircraft "falls" gently into the canopy, vegetation cushions the impact.

Soft field (mud, loose sand, snow)

Procedure for off-field landing on soft ground (FAA-H-8083-3B):

1. Tighten seat belts (crew and passengers).
2. Touch down at minimum speed (Vstall + 5).
3. Hold yoke fully back until full stop — nose stays up, less digging in, lower nose-over probability.
4. Be prepared for possible rollover — in very soft ground the nose wheel can sink in and tip the aircraft onto nose / roof.

Water

See lesson "Ditching".

Retractable gear on off-field landing

Standard rule (consult POH!):

• On hard/firm ground (concrete, paved runway, harvested field): extend gear — friction braking, less damage.
• On soft ground (mud, snow, tall grass, water): retract gear — prevents rollover from sinking in.

General (FAA-H-8083-3B): for an off-field landing in an aircraft with retractable gear, the gear should generally be extended unless the flight manual provides otherwise.

Before touchdown — shutdown

For an emergency landing, the following steps should be completed before touchdown:

1. Close fuel shut-off valve (fuel selector OFF).
2. Ignition off (magnetos OFF).
3. Master switch OFF.

Sequence: fuel away first, then ignition off, then electrical system off. This minimises risk of fire and electrical sparks.

In addition: 4. Mixture IDLE CUT-OFF (some POHs prefer this before fuel selector). 5. Doors unlatched. 6. Seat belts tight.

Brace position before impact

• Head down, arms over head crossed.
• Legs extended and braced against the seat edge.
• Crew and passengers simultaneously.

Core principle in aircraft accidents — "Save persons first"

The foremost principle in an aircraft accident is: save persons first. Material damage is secondary.

• Pilot evacuates passengers BEFORE anything else.
• Only then: secure the aircraft (master off, fuel off), radio distress if not already done.
• → Pilot stays actively conscious, coordinates evacuation.

After emergency landing — behaviour when rescue arrives

After an off-field landing with an ongoing rescue mission (mayday declared, SAR on the way):

• Pilot and passengers wait at the aircraft for the rescue team (at safe distance — secondary-fire risk).
• Do not walk away from the accident site — the ELT activation point and last known position are the most important search indicators. A pilot walking away is harder to find.
• Be visible (mirror, smoke, signal cloth, phone flash).
• If casualties: provide first aid, further movement only in acute danger.

Common causes for engine failure in cruise

NTSB statistics:

1. Fuel exhaustion / starvation — biggest share.
2. Mechanical defect (piston, ignition).
3. Carburettor icing (see Subject 050).
4. Oil starvation / cooling problem.
5. Pilot error (wrong tank, mixture cut-off forgotten).

Prevention

• Fuel plan exact and double-checked.
• Fuel check every 30 min in flight.
• Carburettor icing awareness — carb heat in critical conditions.
• Engine monitoring (oil T/P, CHT, EGT regularly).