FCTM: Crosswind Takeoff

한 줄 요약: 측풍 20 kt 초과 시 rolling takeoff 필수, control wheel into wind + rudder alignment 유지하며 정상 rotation rate로 이륙

1. 적용 상황 (FCTM 3.12)

측풍 성분이 존재하는 활주로에서 이륙 시 적용 (FCTM 3.12). 특히:

• Crosswind > 20 kt → rolling takeoff 강력 권고 (FCTM 3.12)
• Tailwind > 5 kt → rolling takeoff 강력 권고 (FCTM 3.12)
• Wet/contaminated runway + crosswind → 강화된 directional control 필요

🚨 LIMITATION

Maximum demonstrated crosswind: 38 knots (10 m tower height). Dry runway, all engines operating 기준. Limitation이 아님 — operator crosswind policy 별도 적용 (AFM)

💬 ENGINE SURGE RISK

“Engine stress and possible engine surge can occur with a strong crosswind or tailwind component if takeoff thrust is set before brake release.” (FCTM 3.12) → rolling takeoff 사용 이유

2. PF/PM Role (FCTM 3.12)

PF (Pilot Flying)

Ground Roll (< 80 kt)

1. Initial runway alignment → smooth symmetrical thrust application (FCTM 3.12)
2. Forward pressure on control column — nosewheel steering 효과 증가. Crosswind 증가 시 forward pressure도 증가. Strong crosswind + aft CG → full forward column 필요할 수 있음 (FCTM 3.12)
3. Centerline 이탈 시 → immediate, smooth, positive rudder + control wheel 입력 (FCTM 3.12)
4. Airspeed < 80 kt → up to full upwind rudder 필요 가능 (nacelle turning tendency) (FCTM 3.12)

Rotation & Liftoff

1. Control wheel approximately centered로 takeoff roll 시작 (FCTM 3.12)
2. Roll 중 gradually increase control wheel displacement into the wind — wings level 유지에 필요한 만큼만 (FCTM 3.12)
3. Liftoff 후 → sideslip 상태. Slowly, smoothly neutralize control wheel + rudder pedals (FCTM 3.12)

PM (Pilot Monitoring)

1. Wet/slippery runway: 엔진 추력 좌우 대칭(symmetrically balanced thrust) 특별 주의 확인 (FCTM 3.12)
2. Airspeed, heading deviation 모니터링

💡 KEY TECHNIQUE

“Throughout the takeoff roll, gradually increase control wheel displacement into the wind only enough to maintain approximately wings level.” (FCTM 3.12) — 과도한 control wheel 입력 → spoiler deployment 증가 → drag 증가 + lift 감소 → tail clearance 감소, takeoff roll 증가

3. Decision Flow (FCTM 3.12)

flowchart TD
    A[Crosswind Takeoff 결정] --> B{Crosswind > 20 kt?}
    B -- Yes --> C[Rolling Takeoff 사용]
    B -- No --> D{Contaminated Rwy?}
    D -- Yes --> C
    D -- No --> E[Standing or Rolling 선택 가능]
    C --> F{Gusty/Strong Crosswind?}
    E --> F
    F -- Yes --> G[Higher thrust 설정, VR 증가 고려]
    F -- No --> H[Normal thrust, Normal VR]
    G --> I{VR 증가 적용?}
    I -- Yes --> J[VR = Performance limited GW의 VR, 단 actual GW VR + 20 kt 이하]
    I -- No --> H
    J --> K[V speeds는 actual GW 기준 설정, Adjusted VR에서 rotate]
    H --> L[Rotate: control wheel into wind, normal rate]
    K --> L

Crosswind Takeoff Guidelines — Non-TALPA (FCTM 3.12)

아래 가이드라인은 flight test data, engineering analysis, simulator evaluation 기반. Steady wind(no gust) 기준, all engines + engine inoperative 포함. Limitation이 아님 — operator policy 수립 참고용 (FCTM 3.12).

TO Weight	Runway Condition	CG 30% or Less	CG 35%	CG 39%	TO Aft Limit
550 klbs (250 t) 이상	Dry	40	40	40	29
	Wet	40	40	34	25
	Slush/Standing Water	35	31	27	21
	Snow – No Melting	35	29	24	18
	Ice – No Melting	15	15	15	10
470 klbs (215 t)	Dry	40	40	33	24
	Wet	40	34	29	21
	Slush/Standing Water	31	27	23	18
	Snow – No Melting	30	25	21	16
	Ice – No Melting	15	15	15	10
390 klbs (180 t) 이하	Dry	40	33	28	22
	Wet	35	29	24	20
	Slush/Standing Water	28	24	20	17
	Snow – No Melting	27	22	19	16
	Ice – No Melting	15	15	15	10

Interpolation permitted for intermediate gross weights and CG positions. (FCTM 3.12)

⚠️ GOTCHA

• 가이드라인은 runway width ≥ 148 ft (45 m) 기준. 좁은 활주로는 별도 고려 (FCTM 3.12)
• 390 klbs 이하에서 TO aft CG limit < 39% MAC이고 airplane CG > 35% MAC → “35% MAC”과 “TO Aft Limit” 칼럼 사이를 interpolate (FCTM 3.12)
• Untreated snow/ice: no melting 조건에서만 takeoff 시도 (FCTM 3.12)

Gusty Wind & Strong Crosswind (FCTM 3.12)

• Higher thrust 설정 권고 (required minimum 이상). Wind 90° → gusty tailwind 가능성 → maximum takeoff thrust 고려 (FCTM 3.12)
• VR 증가 (tail clearance 확보) (FCTM 3.12):
  • VR = performance-limited gross weight의 rotation speed (FCTM 3.12)
  • actual GW VR + 20 kt 초과 금지 (FCTM 3.12)
  • V speeds는 actual gross weight 기준 설정 → adjusted VR에서 rotate (FCTM 3.12)
• Gust 중 rotation 회피: VR 근처에서 gust 발생 시 (airspeed stagnant or rapid acceleration) → momentarily delay rotation → airspeed 증가 → tail clearance margin 개선 (FCTM 3.12)

4. Common Errors (FCTM 3.12)

⚠️ COMMON ERROR

• Excessive control wheel displacement during rotation/liftoff → spoiler deployment 증가 → drag↑, lift↓ → tail clearance 감소, takeoff roll 증가 (FCTM 3.12)
• Large control wheel inputs near V1 (MCG) → extended spoiler의 추가 drag로 directional control 악화 (FCTM 3.12)
• Brake release 전 takeoff thrust 설정 (crosswind > 20 kt) → engine surge 위험. Rolling takeoff 미사용 (FCTM 3.12)

5. Company Policy (REF)

Auto Land Wind Limitations (REF 6-1):

Wind	CAT II/III	B777-200 CAT I+	B777-300 CAT I+	B777-300ER CAT I+	B777F CAT I+
Headwind	25	25	29/27	40/33	30/28
Tailwind	10	10	10	10	10
Crosswind	15	25	28/30	28/29	27/25

분수 표기: all engines / one engine inoperative (REF 6-1)

⚠️ Boeing vs Company Difference

Boeing: Crosswind guidelines (Not limitations), 최대 40 kt (Dry, Forward CG, Heavy) (FCTM 3.12) Company: 기종별 crosswind limitation 별도 설정 (REF 6-1). Auto Land 시 추가 제한 적용

Cross-References

• Windshear Escape Maneuver (POM 8.3) — 이륙 중 windshear 조우 시 탈출 기동, crosswind 상황에서 windshear 동시 대응 시 참조
• Takeoff Weather Minima (REF) — 이륙 기상 최저치 + wind limitation 상세