Emergencies, Unusual Situations and Contingency Procedures
Emergencies and SAR
Know the distress (MAYDAY) vs urgency (PAN PAN) distinction, the alerting service phases (INCERFA, ALERFA, DETRESFA), and the SAR organisation. A controller must declare the appropriate phase, notify the RCC, and assist. Traps: confusing the three phases and forgetting that the pilot's declared emergency takes precedence over traffic priorities.
Contingency and interception
Contingency procedures cover radio failure, hijacking, bomb threat, and fuel emergency. Interception procedures include the intercepted aircraft's actions (squawk 7700, follow the interceptor, attempt radio contact on 121.5) and the visual signals. Traps: mixing the interceptor and intercepted roles.
Rule of thumb
Distress (MAYDAY) = grave and imminent danger; urgency (PAN PAN) = safety concern without immediate danger. INCERFA = uncertainty; ALERFA = alert; DETRESFA = distress.
Worked example
An aircraft reports low fuel and requests priority. Treat as urgency unless the pilot declares distress; provide priority, alert the tower, and be ready to escalate to DETRESFA if contact is lost.
Aircraft Performance and Wake Turbulence Categories
Categories and performance
Wake turbulence categories are based on maximum certificated take-off mass: Super (A380-type), Heavy (≥136 000 kg), Medium (7 000–136 000 kg), Light (≤7 000 kg). Separation behind a heavier aircraft is greater. Performance concepts: take-off distance, landing distance, climb gradients, V1/VR/V2, and the effect of mass, altitude, temperature and wind. Traps: assuming category depends on wingspan (it does not, except for the Super designation) and forgetting that wake separation is applied to the follower behind the leader.
Wake behaviour
Wake vortices sink and drift with wind; they are strongest when the generating aircraft is heavy, clean and slow. A light aircraft behind a heavy on approach is the classic hazard. Reduced separation may be permitted only with specific approval and conditions.
Rule of thumb
Identify the leader and follower, then apply the wake matrix; never reduce below the wake minimum even if radar allows less.
Worked example
A Light aircraft follows a Heavy on final. Radar minimum might be 3 NM, but wake separation requires more; the controller applies the larger wake value and warns the Light pilot of possible wake turbulence.