Thunderstorm penetration procedure

Thunderstorm unavoidable: fly fixed procedure, not instinct (TC AIM AIR 2.7.2).

Before entering:

• Tighten seat belt and shoulder harness. Secure loose objects.
• Plan minimum-time course through storm. Hold it.
• Penetrate below the freezing level or above the -15°C level. Band between is the most critical icing.
• Turn on pitot, carburetor, or jet inlet heat. Icing can cause almost instant power failure or loss of airspeed indication.
• Set power for turbulence penetration airspeed (aircraft manual).
• Cockpit lights full bright: limits temporary blindness from lightning.
• Disengage autopilot altitude hold and speed hold. Automatic modes fight turbulence, add structural stress.

Once inside:

• Eyes on instruments. Looking outside raises lightning blindness risk.
• Hold penetration power. No changes.
• Do not chase altitude. Let aircraft "ride the waves": manoeuvring to hold altitude adds structural stress. Tell ATC ASAP if altitude cannot be held.
• Do not turn back. Straight flight clears storm faster and adds less stress than turning.

Trap: chasing altitude and airspeed back to pre-storm numbers is backwards. Hold power, accept excursions.

Practice