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3. jar 25 weights

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This document discusses various takeoff weight limits for aircraft, including: - Maximum takeoff weight (MTOW) and runway limited weight (RLW), which define the maximum allowable takeoff weight. - Second segment limited weight (SSLW), which is determined by climb requirements after takeoff with one engine inoperative. Factors like flap setting and density altitude affect SSLW. - Obstacle limited takeoff weight (OLTOW), which ensures adequate obstacle clearance after takeoff. Distance to obstacles, wind, engine bleed settings, and flap setting impact OLTOW. - Runway bearing capacity, which considers the aircraft classification number (ACN) and pavement classification number

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3. WEIGHTS Performance JAR 25
WEIGHTS Takeoff weights MTOW RLW SSLW & FSLW OLTOW Weight limited by Vmbe or Vmaxtire Runway Bearing Capacity
TAKEOFF WEIGHTS Remember that the ATOW must be equal or lower than the lowest of: OTOW MZFW + Takeoff Fuel OLW + Trip fuel
TAKEOFF WEIGHTS The OTOW is given by the lower of: MTOW Runway Limited Weight (RLW) Segment Limited Weight (SSLW, FSLW) Obstacle Limited Takeoff Weight (OLTOW) Weight limited by Vmbe or Vmaxtire
3. jar 25 weights
SSLW The Second Segment Limited Weight (SSLW) or Climb Limited Takeoff weight is determined by the climb requirements just after takeoff assuming one engine inoperative. The second segment begins with the landing gear retracted and ends at level-off altitude (at least 400 ft). CONFIGURATION CLIMB REQUIREMENTS Takeoff thrust set 2 engines: 2.4% Takeoff flap 3 engines: 2.7% Gear up 4 engines: 3.0% V2 speed
SSLW Some factors that affect SSLW are DA, engine bleed and flaps. Low flap settings will decrease RLW and increase SSLW, and vice versa. The optimum flap setting will be a compromise between the two. Using the improved climb performance procedure (V2 + 10 climb) will increase the SSLW, paying the price of a RLW reduction. Flap OTOW RLW SSLW Optimum flap
3. jar 25 weights
OLTOW The Obstacle Limited Takeoff Weight (OLTOW) is determined by the obstacle clearance (35 ft) within the departure sector.
OLTOW Factors that affect OLTOW are: Distance to obstacles Wind Density altitude Engine bleed (A/C, anti-ice) Flap setting
3. jar 25 weights
RUNWAY BEARING CAPACITY The runway strength may be not enough to bear the weight of a heavy aeroplane. Depending on the mass, number of tyres, pressure of tyres, etc, two classifications have been established: ACN: Aircraft Classification Number. It represents the load that the aircraft puts onto the runway and taxiways. PCN: Pavement Classification Number. It must be equal or higher than the ACN to permit operation of the aircraft.
PCN CODE 1. PCN number 5. Pavement evaluation method 2. Type of pavement T = technical evaluation R = Rigid U = By experience F = Flexible 3. Pavement subgrade category EXAMPLES: A = High 25 / F / B / X / T B = Medium 59 / R / A / W / T C = Low D = Ultra low 4. Maximum tyre pressure authorised W = High, no limit X = Medium (max. 217 psi) Y = Low (max 145 psi) Z = Very low (max 73 psi)

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3. jar 25 weights

  • 2. WEIGHTS Takeoff weights MTOW RLW SSLW & FSLW OLTOW Weight limited by Vmbe or Vmaxtire Runway Bearing Capacity
  • 3. TAKEOFF WEIGHTS Remember that the ATOW must be equal or lower than the lowest of: OTOW MZFW + Takeoff Fuel OLW + Trip fuel
  • 4. TAKEOFF WEIGHTS The OTOW is given by the lower of: MTOW Runway Limited Weight (RLW) Segment Limited Weight (SSLW, FSLW) Obstacle Limited Takeoff Weight (OLTOW) Weight limited by Vmbe or Vmaxtire
  • 6. SSLW The Second Segment Limited Weight (SSLW) or Climb Limited Takeoff weight is determined by the climb requirements just after takeoff assuming one engine inoperative. The second segment begins with the landing gear retracted and ends at level-off altitude (at least 400 ft). CONFIGURATION CLIMB REQUIREMENTS Takeoff thrust set 2 engines: 2.4% Takeoff flap 3 engines: 2.7% Gear up 4 engines: 3.0% V2 speed
  • 7. SSLW Some factors that affect SSLW are DA, engine bleed and flaps. Low flap settings will decrease RLW and increase SSLW, and vice versa. The optimum flap setting will be a compromise between the two. Using the improved climb performance procedure (V2 + 10 climb) will increase the SSLW, paying the price of a RLW reduction. Flap OTOW RLW SSLW Optimum flap
  • 9. OLTOW The Obstacle Limited Takeoff Weight (OLTOW) is determined by the obstacle clearance (35 ft) within the departure sector.
  • 10. OLTOW Factors that affect OLTOW are: Distance to obstacles Wind Density altitude Engine bleed (A/C, anti-ice) Flap setting
  • 12. RUNWAY BEARING CAPACITY The runway strength may be not enough to bear the weight of a heavy aeroplane. Depending on the mass, number of tyres, pressure of tyres, etc, two classifications have been established: ACN: Aircraft Classification Number. It represents the load that the aircraft puts onto the runway and taxiways. PCN: Pavement Classification Number. It must be equal or higher than the ACN to permit operation of the aircraft.
  • 13. PCN CODE 1. PCN number 5. Pavement evaluation method 2. Type of pavement T = technical evaluation R = Rigid U = By experience F = Flexible 3. Pavement subgrade category EXAMPLES: A = High 25 / F / B / X / T B = Medium 59 / R / A / W / T C = Low D = Ultra low 4. Maximum tyre pressure authorised W = High, no limit X = Medium (max. 217 psi) Y = Low (max 145 psi) Z = Very low (max 73 psi)