1
Volcanic Ash Cloud — Diversion to HND
ATC-1
✈ SIN → NRT | DVT → HND
📖 Scenario
En route from Singapore to Narita, ATC advises that the destination has been diverted to Haneda due to volcanic ash cloud (VA CLD) activity. The tops of the ash cloud are reported at FL300. As the pilot, you provide a PIREP to ATC and discuss avoidance strategy. You note that volcanic ash can reach up to FL300, so avoiding the upwind side is preferable.
ATC:JL712, be advised volcanic ash cloud reported in the NRT TMA, tops FL300. Destination revised to RJTT. Confirm able to accept HND.
PILOT:JL712, affirm, accepting RJTT. We have visual contact with the ash cloud, request deviation to the right, upwind side, to avoid volcanic ash.
ATC:JL712, deviation approved. Do you have any PIREP on the ash cloud?
PILOT:JL712, PIREP: volcanic ash cloud visible 30 miles northwest of RJAA, tops estimated FL300, extending from surface, avoiding by deviating right. No ash encounter at this time.
⚠️ Volcanic ash is invisible to weather radar. Only PIREP and SIGMET/NOTAM provide reliable warnings. Always avoid the upwind side — ash drifts downwind from the source.
💬 Examiner Q&A
1Is a 20-mile deviation enough to safely avoid volcanic ash?
Not necessarily. Volcanic ash dispersal depends on wind speed, direction, and eruption intensity. ICAO and most operators recommend a minimum of 50 to 100 nautical miles from the ash cloud boundary, and climbing above the ash tops if performance allows. A 20-mile deviation may be insufficient if winds are shifting.
2Why can you not simply climb above the volcanic ash cloud?
If the ash tops are at FL300, climbing above would require FL310 or higher. Aircraft performance may be limited at high weight, and ATC may have conflicting traffic at those levels. Additionally, thin ash layers can exist above the visible cloud tops undetected by weather radar.
3How does volcanic ash affect jet engines?
Volcanic ash melts inside the hot section of the engine and re-solidifies as glass on turbine blades and nozzle guide vanes. This causes engine flameout, compressor stall, and severe damage. The ash also abrades fan blades, erodes windscreens, and can block pitot systems. Even brief encounters can cause significant damage.
4If a volcanic island were erupting along your route, what actions would you take?
We would check the latest SIGMET and NOTAM for the volcanic ash advisory area, request the earliest possible deviation or route change from ATC, provide a PIREP, increase our distance from the source, and contact the company for updated routing. If ash is encountered, we would execute the volcanic ash encounter drill — throttle back, start APU, and exit the ash cloud.
Key Vocabulary
volcanic ash cloud
VA CLD
PIREP
SIGMET
upwind
diversion
ash tops
engine flameout
2
Wind Shear PIREP — Go-Around at HND
ATC-2
✈ FUK → HND | ILS Z34L
📖 Scenario
You have been cleared for ILS Z RWY34L at HND. During the approach, a PIREP from a preceding Boeing 737 reports a 15-knot airspeed loss at 500 feet — a wind shear event. Tower issues a wind shear alert. You execute a go-around and receive vectors from Approach. ATC then requests your PIREP to pass to following traffic.
TWR:JL315, PIREP from preceding B737: 15-knot airspeed loss at 500 feet. Wind shear alert, wind shear on final. Cleared ILS Z runway 34L.
PILOT:JL315, acknowledge wind shear alert, continuing, ILS runway 34L.
⚠️ Airspeed loss of 15kt at 500ft — crew executes go-around.
PILOT:JL315, going around, encountered wind shear, 15-knot loss at 500 feet.
TWR:JL315, roger, fly present heading, climb and maintain 3,000 feet. Contact Approach 119.7.
PILOT:Present heading, climbing 3,000, contacting 119.7, JL315.
APP:JL315, Tokyo Approach, direct UTIBO, climb and maintain 5,000. Do you have a PIREP for the wind shear?
PILOT:JL315, direct UTIBO, climbing 5,000. PIREP: wind shear on ILS 34L final, 15-knot airspeed loss at 500 feet, associated with go-around.
💬 Examiner Q&A
1Have you ever experienced wind shear? What happened?
Yes. On final approach, the airspeed suddenly dropped 15 knots and the aircraft began to sink below the glidepath. We applied go-around thrust immediately, reconfigured, and executed the go-around. We reported the event to ATC as a PIREP to alert following traffic.
2Why is a 15-knot airspeed loss at 500 feet particularly dangerous?
At 500 feet on final, the aircraft is close to the ground with limited altitude to recover. A 15-knot loss reduces lift and causes the aircraft to sink rapidly. The pilot must react immediately with go-around thrust. Delay of even a few seconds can result in controlled flight into terrain or a hard landing short of the runway.
3What is a wind shear escape maneuver?
The wind shear escape maneuver involves applying maximum available thrust simultaneously with a pitch increase to the go-around attitude, as per the aircraft's QRH or normal procedures. We do not retract flaps until safely clear of the ground. The pitch target varies by aircraft type — for the 787 it is approximately 17.5 degrees initially.
4What onboard system provides wind shear warnings?
The Enhanced Ground Proximity Warning System (EGPWS) provides predictive wind shear alerts in the form of "Wind Shear, Wind Shear, Wind Shear" audio and visual warning. The alert triggers when the system predicts a shear will be encountered within the next 15 seconds based on sensor data from the air data system.
Key Vocabulary
wind shear
airspeed loss
wind shear alert
escape maneuver
PIREP
going around
EGPWS
predictive wind shear
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