Engine Failure After V1 on a Hot, High-Gross-Weight Departure
You are PF in a twin-engine turbofan, mass 66 000 kg (MTOW 70 000 kg), departing a 2400 m runway at 1800 ft elevation, OAT 36 °C, QNH 1010. V1 = 138 kt, VR = 142 kt, V2 = 148 kt. At V1 + 5 kt the right engine fails; you identify and confirm, and the aircraft yaws right. The left engine is at take-off thrust. The aircraft is 300 m from the end of the runway at 120 ft AGL, gear still down, speed 152 kt. The second segment obstacle is a 60 m building 4 km from the end of the runway. The AFM gives a second-segment gross gradient of 2.4 % at this mass, temperature and altitude, and a take-off flight path gross gradient of 3.1 % after gear retraction.
1. Verify whether the aircraft can meet the second-segment climb requirement and state the required actions in order.
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Second-segment requirement. For a twin, the net second-segment gradient must be ≥ 2.4 % (CS/FAR 25.121). Net = gross − 0.8 %.
- Gross second-segment gradient at this mass/temp/altitude = 2.4 % → net = 1.6 %, which is below 2.4 %. The aircraft does not meet the second-segment requirement at 66 000 kg in these conditions.
This means the take-off was not legal as planned - the field-length/obstacle-limited mass should have been reduced (or a derate avoided) so that the net second segment was ≥ 2.4 %. The error is on the ground, not in the air; in the air, the crew must still fly the aircraft.
Actions in order:
- Fly the aircraft - maintain directional control with rudder, do not over-control; the yaw is expected.
- Confirm the failed engine (identify, confirm, feather/secure per SOP). Do not rush the shutdown.
- Maintain V2 (148 kt) to the end of the second segment; do not accelerate below V2.
- Retract the gear once a positive rate is established and there is no runway remaining - gear drag is the largest single penalty.
- Do not retract flaps until the acceleration altitude.
- Advise ATC ('Mayday, engine failure, maintaining V2, request vectors for return').
- At the acceleration altitude, accelerate, clean up, and plan a return for an overweight landing (66 000 kg is below MLM, so no overweight issue) or a diversion.
Key point: the aircraft will not achieve the scheduled second-segment gradient; the crew must expect a reduced climb rate and should not attempt to climb to a high altitude. Level off at a safe altitude and return.
2. Compute the obstacle clearance at the 60 m building using the take-off flight path gradient and state whether it is satisfactory.
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Geometry.
- At 120 ft AGL (≈ 37 m) and 300 m from the runway end, the aircraft is at the start of the take-off flight path.
- The building is 60 m high, 4 km from the runway end, i.e. 3 700 m ahead of the aircraft.
- The take-off flight path gross gradient is 3.1 %; net = 3.1 − 0.8 = 2.3 %.
Height gain over 3 700 m at 2.3 % net = 0.023 × 3 700 = 85 m. Aircraft height at the building = 37 + 85 = 122 m above the runway end datum. Building top = 60 m. Clearance = 62 m ≈ 203 ft.
Required clearance for the take-off flight path is 35 ft vertically. 203 ft > 35 ft → satisfactory on the net flight path.
Caveats the examiner wants:
- The net gradient must be used, not the gross; using gross (3.1 %) gives 115 m gain and 152 m height, which overstates the margin.
- The 3.1 % figure is valid only after gear retraction and at the take-off flight path speed, not at V2 with gear down. If the gear is still down at the building, the gradient is much lower (the second-segment 2.4 % gross applies) and the clearance collapses to 37 + 0.024 × 3 700 − 60 = 66 m - still above 35 ft, but the margin is thin.
- Temperature: 36 °C at 1800 ft is well above ISA (ISA at 1800 ft ≈ 11 °C), so the AFM gradient must be read at the actual OAT, not ISA.
3. The crew considers returning to the departure airfield. The landing mass will be 64 500 kg, MLM 66 000 kg, LDA 2 100 m (displaced threshold), OAT 36 °C, dry runway. State the landing feasibility and the key considerations.
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Mass. 64 500 kg ≤ 66 000 kg MLM ✔ - no overweight landing, no inspection required for overweight.
Landing distance. The AFM dry landing distance at 64 500 kg, sea level, ISA is, say, 1 500 m. Corrections:
- Temperature: 36 °C vs ISA at 1800 ft (≈ 11 °C) → ΔT ≈ +25 °C → about +25 % → 1 875 m.
- Altitude: already in the AFM figure if read at 1800 ft; if not, add ~5 % per 1000 ft → about +9 % → 2 040 m.
- Runway slope and wind: wind 120°/18 kt - if landing on the same runway into wind, a headwind reduces distance; if downwind, add 15 %.
Factored landing distance = actual × 1.67 (dry) or × 1.92 (wet). With a dry runway and 1 500 m actual, factored ≈ 2 500 m > LDA 2 100 m → not satisfactory unless the AFM figure is lower or the wind is a headwind.
Key considerations:
- Displaced threshold reduces LDA to 2 100 m - check the actual LDA, not the runway length.
- High OAT increases true landing distance; use the AFM at the actual temperature.
- One engine inoperative - the landing distance is flown on one engine; the approach is a single-engine approach, and a go-around must be planned with the remaining engine's performance.
- Braking action - dry, so the dry factor applies.
- Fuel - landing at 64 500 kg implies little fuel burned; consider holding to reduce mass if the landing distance is marginal, but do not compromise the engine-out situation.
Decision: if the factored distance exceeds the LDA, divert to a longer runway; do not force the landing on a marginal runway with one engine.